Kashrut I

01. The Omer Offering and the Prohibition of Ḥadash

Every year, on the day after the first day of Pesaḥ – the 16th of Nisan – there is a mitzva to offer the first of the new grain as a meal offering to God, so that the first of each year’s harvest is dedicated to Him. In addition, one may not eat from the new grain before the Omer offering has been brought, and one may not harvest the new grain before the barley for the Omer offering has been harvested. The Torah states (Vayikra 23:9–14):

The Lord spoke to Moshe, saying: Speak to the children of Israel and say to them: When you come into the land that I am giving you and reap its harvest, you shall bring the Omer, the first of your harvest, to the kohen. He shall wave the Omer before the Lord, that it may be accepted on your behalf; on the day after the “Shabbat” the kohen shall wave it. On the day you wave the Omer, you shall offer an unblemished yearling lamb as an olah to the Lord. Its meal offering shall be two-tenths of an eifa of fine flour mixed with oil, a fire offering to the Lord, a pleasing aroma; and its libation shall be a quarter of a hin of wine. You shall eat neither bread, nor parched grain, nor fresh grain until this very day, until you have brought the offering of your God – an everlasting statute throughout your generations in all your dwellings.

The Omer offering is brought on the day after the first festival day of Pesaḥ. This is the Sages’ received tradition in interpreting the verse’s phrase, “the day after the Shabbat”: the day after the rest of the first Yom Tov of Pesaḥ. The rest of that day is meant to strengthen our faith through the memory of the Exodus and the mitzva of eating matza on the Seder night. Having deepened that faith, we are then commanded to offer the new grain, so that all our eating throughout the coming year is shaped by that intention. Since the day of the Omer offering is fixed, its harvesting, preparation, and offering override Shabbat even when it falls on Shabbat.

Although wheat is the finest of the five species of grain, the Omer offering is brought from barley. This is the tradition transmitted from Moshe at Sinai, and it also reflects agricultural reality: in Eretz Yisrael, barley ripens before Pesaḥ, while wheat ripens only later. This choice is also significant. Barley is animal feed, and it represents the basic, lower side of human life. Precisely because this side of life emerges first, it too must be connected to holiness. From the night of the Omer harvest, we count seven weeks — forty-nine days — during which we prepare ourselves to receive the Torah on Shavu’ot, when we are commanded to bring the shtei ha-leḥem, the “two loaves,” the first offering brought from that year’s new wheat.

The Omer permits all Israel to eat from the new crop; the shtei ha-leḥem permits meal offerings from the new crop to be brought in the Temple. (Menaḥot 68b; see Peninei Halakha: Mo’adim 13:7).

The mitzva of harvesting the Omer is performed on the night of the 16th of Nisan, and the harvest may be done at any point during the night. Ideally, the barley should be grown near Jerusalem. If the nearby barley had not yet ripened, it could be brought from farther away, provided it was grown in Eretz Yisrael. The Omer was customarily harvested and brought to the Temple courtyard in a dignified ceremony, before a large public gathering, in order to reinforce the Sages’ tradition regarding this mitzva. Once it was brought to the courtyard, the kernels were removed from the ears, lightly roasted, and ground. The resulting flour was then sifted through thirteen sieves.

The next day, after the daily offering and the additional festival offering were brought, one-tenth of an eifa was taken from that flour, mixed with one log of oil, and a handful of frankincense was placed upon it. The kohen waved it before God, took a handful from it, and burned it on the altar. Once this handful was burned, all Israel was permitted to eat from the new grain (Menaḥot 63–68; MT, Laws of Temidin u-Musafin 7:3–12).

2. The Mitzva Across Time and Place

Until Israel entered the Land, they were not obligated to bring the Omer offering, and there was no restriction on eating from the new grain. On the 10th of Nisan in the year 2489 from Creation, Israel crossed the Jordan and entered Eretz Yisrael. From that point onward, it became forbidden to eat from the new grain before the Omer was brought. This prohibition applies not only in Eretz Yisrael but throughout the world, and it applies both to grain owned by Jews and to grain owned by gentiles, as the verse states: “an everlasting statute throughout your generations in all your dwellings” (Vayikra 23:14; see below, section 5).

The prohibition remained in force even after the destruction of the Temple, as the verse states, “an everlasting statute throughout your generations.” When the Temple stood, the new grain became permitted once the Omer was offered on the 16th of Nisan. After the destruction, however, it becomes permitted only after the 16th of Nisan has fully passed, as the verse also says, “until this very day, until you have brought the offering of your God.” When the Temple is standing, the determining phrase is “until you have brought the offering of your God”; when the Temple is no longer standing, it is “until this very day.” In the Diaspora, where two festival days are observed, one must wait an additional day; the new grain therefore becomes permitted only after the 17th of Nisan has ended (Menaḥot 68b; MT, Laws of Forbidden Foods 10:2; SA YD 293:1).

This mitzva is rooted in the fact that grain provides the staple of human nourishment; for that reason, the divine values bound up in it must be given special expression. The Torah therefore commands us to restrain ourselves and not eat from the new grain before offering its first portion to God. In this way, we return our food to its sacred root and prepare ourselves to receive His goodness as we eat. Through this, holiness and divine values illuminate our eating throughout the year. Yet only after Israel entered the Land was its holiness revealed, enabling grain to be connected to its sacred root through the Omer offering.

Even now, when the Temple is destroyed and we cannot offer the Omer, this awareness still elevates the Jewish people and shapes our eating: the first portion of the grain should have been offered to God, and for that reason one may not eat from the new grain until the day of the Omer (see Sefer ha-Ḥinukh §303; Ḥizkuni to Vayikra 23:10; below, 2:2).

3. The Prohibition of Ḥadash

The prohibition of ḥadash applies to the five grain species from which bread is made: wheat, barley, spelt, oats, and rye, as the verse states (Vayikra 23:14): “You shall eat neither bread, nor parched grain, nor fresh grain until this very day.” Bread is made from flour produced from these five grains, which are capable of becoming ḥametz. If dough made from them is left to stand, it ferments, allowing it to become fine bread, the staple of human nourishment. By contrast, if the dough is kneaded and baked quickly, before it has time to ferment, it becomes “bread of affliction” (leḥem oni) – the matza we are commanded to eat on Pesaḥ (Menaḥot 70a–b).

Ḥadash – grain subject to the prohibition of the new crop – may not be eaten, but one may derive benefit from it. Therefore, one may feed ḥadash to animals (Mishna, Menaḥot 10:8; Pesaḥim 23a). Likewise, one may sell ḥadash to a gentile, provided there is no concern that Jews will come to eat it.

The Torah specifies “bread, parched grain, and fresh grain” to teach that new grain is prohibited in every edible form. “Bread” is the most refined form, since its preparation requires grinding the kernels, kneading the flour with water, and baking the dough. “Parched grain” (kali) refers to kernels roasted over fire, while “fresh grain” (karmel) refers to raw kernels eaten as they are. Cooked dishes made from new grain are included in the prohibition as well, since the prohibition of ḥadash takes effect once the grain has reached the stage of karmel, and cooking does not remove that status. The prohibition also includes all flour products, such as bran, coarse bran, starch, and gluten, as well as oatmeal, which is made from crushed oats. Beverages produced from new grain are included as well, whether made by pressing, cooking, or brewing – such as beer and other grain-based drinks.^[1]

Any grain that had taken root by the 16th of Nisan – even if it had not yet emerged above ground – is permitted on the day of the Omer. Grain that had not taken root by the 16th of Nisan is not permitted by the Omer that year and remains forbidden until the Omer of the following year. Grain seeds are presumed to take root in the soil two weeks after they are sown (Dagul Me-Revava; R. Akiva Eiger). Some authorities maintain that grain takes root within only three days of sowing (Terumat Ha-deshen). Since this is a Torah prohibition, the halakha follows the stringent view. However, if it is known with certainty that the grain took root before the 16th of Nisan, it becomes permitted on the day of the Omer even if two full weeks have not passed since sowing (see Yerushalmi, Shevi’it 2:4).

The prohibition of ḥadash applies to all grain, including grain grown in an unperforated pot or in water (Rashash to Pesaḥim 36b; Divrei David, vol. 4, YD 50:2).

Grain kernels that became permitted on the day of the Omer may be sprouted, and the leaves that grow from them may be eaten without waiting for the next Omer. The prohibition of ḥadash applies to the kernels themselves, even before they have reached one-third of their growth; it does not apply to the stalks (Sha’agat Aryeh, Ḥadash §4).

4. The Prohibition Against Harvesting

One may not harvest any of the five species of grain growing in Eretz Yisrael before the barley for the Omer offering has been harvested. The verse states: “You shall bring an Omer, the first of your harvest, to the kohen” (Vayikra 23:10), teaching that the Omer offering must be the first grain harvested. One who harvests earlier violates this positive mitzva. Nevertheless, the grain that was harvested becomes permitted after the Omer is offered (MT, Laws of Temidin u-Musafin 7:21). Even after the destruction of the Temple, this prohibition remains in effect. The prohibition applies specifically to harvesting with a tool; picking by hand is permitted (Pesaḥim 11a).

The prohibition applies only to grain grown in a place from which the Omer offering may be brought. Therefore, grain grown in beit ha-shelaḥin – manually irrigated fields in valleys – may be harvested before the Omer, since such grain is of inferior quality and unfit for the Omer offering. The Sages, however, decreed that this grain may not be gathered into a heap before the day of the Omer, lest people come to eat it while it is still forbidden as ḥadash. They could have prohibited even its harvest, but because delaying the harvest could damage the crop, they limited the decree to gathering the grain into a heap (Menaḥot 71a; Shita Mekubetzet to Menaḥot 71a; MT, Laws of Temidin u-Musafin 7:13).

Nowadays, in cases where harvesting is permitted, one may harvest with a combine, even though it separates the kernels from the ears during harvesting and gathers them in a grain bin.^[2]

One may likewise harvest new grain growing among young saplings, since such grain is sparse and unfit for the Omer. The Sages also did not prohibit harvesting it, because leaving it in place would damage the young saplings. It is also permitted to harvest new grain for the sake of a mitzva, such as clearing a field to make room for people to sit at a mourners’ meal or for a Torah class. This, too, is because the prohibition applies only to harvesting grain fit for the Omer for personal use, not to harvesting done for the sake of a mitzva.

To prevent people from mistakenly eating this grain, the Sages decreed that it may not be tied into sheaves in the usual way. Rather, it must be left in small, untied bundles called tzevatim. By minimizing the processing, people would remember that the grain is forbidden as ḥadash (Menaḥot 71a, 72a; Rashi to Menaḥot 71a; MT, Laws of Temidin u-Musafin 7:15–16). ^[3]

Before the day of the Omer, one may harvest grain that has not yet reached one-third of its growth if it is being cut for animal fodder, since the harvest is directed primarily toward fodder rather than the kernels. “One-third growth” is the stage at which grain is fit for human consumption in pressing circumstances and, if planted, will grow. ^[4]

Outside Eretz Yisrael, one may harvest grain before the day of the Omer, since the Omer offering may not be brought from grain grown outside the Land. However, authorities disagree over whether the Sages’ decree against gathering the grain into a heap applies there as well.

5. Ḥadash in the Diaspora

Eretz Yisrael is the home of the Jewish people and the place best suited for fulfilling the Torah (Sifrei to Devarim 11:18; Ramban to Vayikra 18:25; below, 13:1). It is also easier to observe the mitzva of ḥadash in Eretz Yisrael, since grain is sown at the beginning of winter and ripens around Pesaḥ. As a result, the Omer permits all types of grain, and one need only refrain from harvesting or eating grain that ripened before Pesaḥ until the day of the Omer. By contrast, in countries where rain falls during the summer as well, sowing is sometimes delayed until after Pesaḥ, so that part of the crop remains forbidden as ḥadash until the Omer of the following year. It was often difficult to determine which grain had taken root before the Omer and was therefore permitted, and which had taken root afterward and remained forbidden until the next Omer. Because this created a pressing difficulty, authorities permitted grain sold in the markets on the basis of a safek sfeika, a double doubt: perhaps the grain was from the previous year; and even if it was from the current year, perhaps it had taken root before the Omer; or perhaps it came from a place where all grain had taken root before the Omer (Ra’avya; Rosh). Others maintain that the prohibition of ḥadash outside Eretz Yisrael is rabbinic, and therefore, in any case of doubt, the halakha follows the lenient view (Or Zaru’a).

When Jews migrated to the cold countries of northern Europe, however, it became far more difficult to avoid violating the prohibition of ḥadash. Since the winters there are severe, grain was sown only toward the end of winter, and often took root only after the day of the Omer. In addition, summer grain was sometimes grown, since in some countries rain falls even in the summer. As a result, there were times when nearly all local grain was ḥadash, yet many ate it without checking whether it would remain forbidden until the following Omer. This was especially problematic with barley and oats, from which beer was made, as it was often clear that they came from the new crop.

In practice, some rabbis urged the public to observe the prohibition despite the difficulty. When the hardship became too great, others refrained from rebuking the community, knowing that their words would not be heeded. They invoked the principle, “Better that they sin inadvertently than deliberately” (Rosh; Rema YD 293:3).

Other authorities, faced with great hardship, sought grounds for leniency. Some maintained that, according to the lenient view in the Mishna, ḥadash does not apply outside Eretz Yisrael at all, and that this view may be relied upon in pressing circumstances (Taz YD 293:4). Others maintained that, according to the lenient view in the Mishna, ḥadash outside Eretz Yisrael is rabbinic and applies only in lands near Eretz Yisrael; therefore, in pressing circumstances, one may permit ḥadash in Europe and other lands far from Eretz Yisrael (AHS YD 293:20, based on Rabbeinu Barukh). Still others maintained that although ḥadash applies throughout the Diaspora, it applies only to grain owned by Jews, not to grain owned by gentiles (Baḥ). The halakhic authorities who issued these rulings were aware that, according to the overwhelming majority of Rishonim, the halakha follows the Tanna’im who maintain that ḥadash outside Eretz Yisrael is prohibited by Torah law even when the grain belongs to a gentile. Nevertheless, because of the great hardship, they relied on minority views and ruled leniently. In those countries, people depended so heavily on beer that it seemed as though “a person’s life truly depends on it” (Taz YD 293:4).^[5]

6. Mixtures and Cases of Doubt

If there is doubt whether grain or grain-containing products are prohibited as ḥadash, they may not be eaten, since one must be stringent in cases of doubt involving Torah prohibitions. This is the practice in Eretz Yisrael: any grain with kosher certification from the Chief Rabbinate is presumed to be free of any concern for ḥadash.

In principle, this should be the practice in the Diaspora as well. Since old grain is now readily available, and the situation is no longer one of pressing need, one should be stringent in cases of doubt concerning ḥadash (see Igrot Moshe, YD 4:46:4). In practice, however, most kashrut agencies in the Diaspora are lenient in such cases, relying on arguments developed in earlier times, when old grain was very difficult to obtain. One who wishes to be lenient outside Eretz Yisrael has authorities upon whom to rely. The more difficult it is to obtain food without concern for ḥadash, the more room there is to rely on the lenient views.

In Eretz Yisrael, however, one should not be lenient, even though most grain is imported. The overwhelming majority of authorities rule stringently, and this has long been the accepted practice in Eretz Yisrael, where cases of doubt can be avoided without difficulty. Therefore, any grain-containing product bearing overseas kashrut certification but lacking Rabbinate approval may not be eaten unless it states explicitly that it was made from old grain or was supervised by a rabbi who is careful about the prohibition of ḥadash, since most Diaspora kashrut agencies are known to be lenient when ḥadash is in doubt.

If ḥadash flour became mixed with other flour, it is not nullified, even if the other flour is a thousand times its quantity. Since ḥadash will become permitted after the day of the Omer, it is a davar she-yesh lo matirin – something that will eventually become permitted – and such an item is not nullified when mixed with its own kind (Nedarim 58a; MT, Laws of Forbidden Foods 15:10).

If, however, the mixture containing the ḥadash is ḥametz, it cannot be kept until the Omer, since the ḥametz must be destroyed before Pesaḥ. Therefore, if the mixture contains sixty times as much permitted food as ḥadash, the ḥadash is nullified and the mixture may be eaten (Ḥokhmat Adam 53; Binat Adam 28). The same applies if the mixture is a food that will spoil before the day of the Omer: the ḥadash is nullified in sixty (Ḥok Yaakov 489:24).

If ḥadash flour became mixed into a different kind of food, it is nullified in sixty, and one need not wait until the day of the Omer. Even a davar she-yesh lo matirin does not prohibit a food of a different kind unless it can impart flavor to it. Once there is sixty times as much permitted food, it can no longer impart flavor and is therefore nullified (SA YD 102:1).

1. The Mitzvot of Orla and Neta Reva’i

The Torah forbids deriving benefit from orla fruit, which grows during the first three years of a tree’s life. It also commands that fourth-year fruit be brought to Jerusalem and eaten there in sanctity, with praise to God. Through this mitzva, blessing extends to the fruit that grows from the fifth year onward. The Torah states: “When you come into the Land and plant any tree for food, you shall treat its fruit as closed off. For three years it shall be closed off to you; it may not be eaten. In the fourth year, all its fruit shall be sacred, for praise of the Lord. In the fifth year, you may eat its fruit, so that it may yield its increase to you. I am the Lord your God” (Vayikra 19:23–25).

The word orla means a blockage. Thus, an “uncircumcised heart” is a heart that is blocked; “uncircumcised ears” are ears blocked from hearing; and “uncircumcised lips” are lips unable to speak freely. From this we learn that the fruit of the first three years is forbidden to us: we may neither eat it nor derive benefit from it (Rashi and Rashbam on Vayikra 19:23).

When the Children of Israel crossed the Jordan in the time of Yehoshua bin Nun and entered the Land, the laws of orla took effect. This follows from the verse: “When you come into the Land and plant.” Even if a gentile planted a tree in his own field after that point, it became subject to orla, and one may not derive benefit from its fruit. The verse says, “any tree for food,” including a tree planted by a gentile (Sifra on Vayikra 19:23).

In the Diaspora, the law of orla applies by virtue of a halakha transmitted to Moshe at Sinai — a tradition that limits the prohibition to cases where the fruit is certainly orla. Thus, in the Diaspora, fruit is forbidden only when it is known with certainty to be orla; if its status is uncertain, it is permitted, even when there is strong reason to presume that it is orla. When it is uncertain whether fruit is orla, the fruit is forbidden in Eretz Yisrael but permitted in the Diaspora (Mishna, Orla 3:7; Yerushalmi, Orla 3:7; Kiddushin 39a; SA YD 294:8; see below, section 11). The boundaries of the Land for this mitzva are the boundaries of those who ascended from Egypt. Even according to those who maintain that the southern Arava lies outside those boundaries, since it is under the sovereignty of the State of Israel, the Torah obligation applies there as well (see below, chapter 12, section 2, note 2, and chapter 17).^[1]
Whether one plants a seed or a cutting, the three years are counted from the time it takes root in the ground (as explained below, section 4).

2. The Reason for the Mitzva

This mitzva honors God with the first of the tree’s fruit: it is eaten in sanctity in Jerusalem, where one praises Him for all the good He has bestowed upon us. Usually, the fruit that grows during the first three years is not especially abundant or choice, and therefore would not bring fitting praise to God. The Torah prohibits that fruit so that the first time we eat from the tree will be an act of sanctity and praise in the fourth year, when the fruit is already plentiful and fine. This allows God’s goodness and blessing to rest upon the fruit of all the coming years. Eating it then remains joined to faith and becomes a source of vitality, goodness, and blessing in the world. The Torah gave similar commands regarding the firstborn of people, the firstborn of animals, and the first fruits. The same principle also underlies the mitzvot of ḥadash, teruma, ḥalla, and reishit ha-gez (see Ramban on Vayikra 19:23–25; Sefer ha-Ḥinukh 246–247).

This mitzva also teaches the value of self-discipline, a virtue of tremendous importance. The ability to restrain oneself and defer gratification is essential for success in this world and the next. A young person who studies diligently is likely to succeed later in his personal life and livelihood; yet many young people are unable to hold themselves back. Swept along by impulse, they waste their time on various diversions. Likewise, friendships between young men and women that are not directed toward marriage can harm their ability to marry and build a loving, faithful home; yet many people are unable to restrain themselves and form intense attachments that do not lead to a true covenant. The same applies to people who cannot restrain themselves from spending money on luxuries, such as buying a home beyond their means. Instead of saving enough to help their children learn a profession and marry, or to support themselves in old age, they spend what should have been set aside. Adam, the first man, too, was swept along by his inclination. He sinned because he did not restrain himself from eating from the Tree of Knowledge of Good and Evil, and thereby brought death upon himself and his descendants. Through the mitzva of orla, a person learns to watch his fruit grow and refrain from deriving benefit from it. As he does so, he learns to overcome his inclination and develop self-discipline. This is what the Sages said: “Who will uncover the dust from your eyes, Adam? You could not stand by your command even for one hour, while your children wait three years for orla” (Vayikra Rabba 25:2; see Beitza 25b).

The Sages further said that the fruit of the first years reflects an urge to appear before its time, without proper restraint. It is therefore incomplete, and impurity clings to it. The fruit of the first three years corresponds to the three dense, impure husks that seal off and conceal the light. The fourth year corresponds to the thin shell in which good and evil are mixed together. Fourth-year fruit is rectified by bringing it to Jerusalem and eating it in sanctity (Zohar 3:87a; Sha’arei Orah, Gate 5; Pardes Rimmonim 25:7).

3. The Prohibition Against Deriving Benefit

One may neither eat nor derive benefit from fruit that grows during a tree’s first three years. For this reason, one may not light a lamp with oil extracted from orla fruit, nor may one fuel an oven with orla fruit. One may not place orla fruit in the ground as fertilizer, although one may throw it onto the ground if he does not intend to fertilize with it. One may not use orla fruit even for a mitzva; therefore, an orla etrog is invalid for the mitzva of the four species on Sukkot (Sukka 34b; SA YD 294:24; Peninei Halakha: Sukkot 4:12). It is likewise forbidden to benefit from the fragrance of orla fruit (SA YD 108:7).^[2]

It is also forbidden to dye a garment with dye produced from orla fruit. A garment dyed with orla fruit may not be used; to prevent people from mistakenly benefiting from it, it must be burned (Yerushalmi, Orla 3:1; Kiddushin 56b). Whenever there is concern that people may derive benefit from orla fruit, there is a mitzva to burn it or destroy it in some other way that makes benefit impossible. When possible, it is good to remove the blossoms or fruit while they are still small, so that people will not mistakenly benefit from them. ^[3]

One may not derive benefit from anything that develops together with the fruit, including the pits, peel, and juice. By contrast, one may derive benefit from the tree itself, its leaves, and its blossoms. One may also derive benefit from semadar — fruit so small that it is not yet considered fruit. Once the fruit reaches the stage of boser — recognizable but still unripe fruit — it is considered fruit, even though it is still unfit to eat, and the prohibition of orla applies (Mishna, Orla 1:7–9; SA YD 294:1–2). ^[4]

It is forbidden to plant the pits of orla fruit. Nor may one place orla fruit in the ground in order to grow a tree from it. One may, however, plant a branch from an orla tree, since one may derive benefit from the wood itself (Mishna, Orla 1:9). If one transgressed and planted orla fruit, one may derive benefit from the tree that grows from it. This is based on the rule of zeh ve-zeh gorem mutar: when two factors together produce something, one forbidden and one permitted, the result is permitted. Here, the two causes are the forbidden fruit and the permitted soil. Therefore, one may derive benefit from the resulting tree (SA YD 294:12).

The prohibition of orla also applies to fruit from a tree owned by a gentile, and a Jew may not derive benefit from that fruit. Nevertheless, a gentile may benefit from orla fruit that grew on his own tree or on a tree owned by a Jew, because the prohibition of orla applies to Jews, not gentiles. Still, since a Jew may not derive benefit from the fruit, he may not sell his orla fruit to a gentile, give it as a gift, or even feed it to an animal, because in each of these cases he derives benefit from it (MT, Laws of Forbidden Foods 8:16).

Before any orla fruit has begun to grow, however, one may sell a gentile the rights to the future crop. Since the Jew receives payment before the fruit exists, he is not deriving benefit from the fruit itself, but from the tree, from which benefit is permitted (SA YD 294:15; Nekudot ha-Kesef on MT, Laws of Forbidden Foods 8:16). This leniency applies only when there is no concern that the gentile will later sell the orla fruit to Jews and cause them to transgress, such as when he sells it in a place where no Jews live.

4. Calculating the Years of Orla

When counting the years of orla, two dates are relevant: the first of Tishrei, which is the New Year for years and for plantings, and the 15th of Shevat, which is the New Year for trees. This is because fruit that reaches ḥanata by the 15th of Shevat is considered to have developed from the rains the tree received during the previous year. We also have another rule: 30 days in a year count as a year (Rosh Hashana 9b–10b).

The calculation works as follows: If the tree took root in the ground by the 29th of Av, then by the first of Tishrei, 30 days will have passed for it, and those 30 days count as a full year. One must then wait another two years to complete the three years. Since the New Year for trees is the 15th of Shevat, one must wait until the 15th of Shevat, because fruit that reaches ḥanata before the 15th of Shevat developed from the rains of the previous year, when the tree was still subject to orla. Thus, if the tree took root on the 29th of Av 5781, all fruit that reaches ḥanata on it before the 15th of Shevat 5784 is orla. Fruit that reaches ḥanata from the 15th of Shevat 5784 until the 15th of Shevat 5785 is neta reva’i. Fruit that reaches ḥanata from the 15th of Shevat 5785 onward is ordinary fruit. In practice, then, orla applies to the tree for two years and five and a half months.

The Sages estimated that a seed or cutting takes 14 days to take root in the ground. Therefore, for a tree to take root by the 29th of Av and have that year counted, it must be planted no later than the 15th of Av. If one plants a sapling together with its root ball, there is no need to wait 14 days, because from the moment it is placed in the ground, it is considered rooted there. Accordingly, if it is placed in the ground by the 29th of Av, that year counts for it.

However, if the tree took root in the ground on the 30th of Av 5781 or later, then since 30 days did not remain for it in 5781, its first year begins only on the first of Tishrei 5782. One must then wait three full years, until the first of Tishrei 5785. Since the New Year for trees is the 15th of Shevat, one must wait several more months, until the 15th of Shevat 5785. Only then does the tree leave its orla status. Thus, if the tree took root in the ground on the 30th of Av 5781, orla applies to it for three years and five and a half months. Some authorities are lenient and maintain that orla never lasts more than three years. However, since orla applies by Torah law, the halakha follows the stringent opinion.^[5]

5. A Tree That Was Uprooted or Cut Down

If a tree was uprooted from its place, but one of its roots remained attached to the ground, and that root was at least as thick as a weaver’s needle used to stretch fabric, one may replant the tree without restarting the orla count. Since it can survive by means of that one root, even if only with difficulty, it can still be considered attached, and its original status does not change. However, if no such root remains, the tree becomes subject to orla anew when it is replanted (SA YD 294:20).

If the wind uprooted a tree, or a river swept it away, yet a clump of soil remained attached to its roots, and that clump can sustain it for at least 14 days, one may replant the tree without restarting the three-year count, even if none of its roots remained attached to the ground itself. If it cannot live from that clump for 14 days, then once replanted, the years of orla must be counted from the start. Therefore, one who needs to move a fruit tree from one place to another must be careful to uproot it together with enough soil to sustain it for 14 days, so that the orla count does not restart. It is also advisable to prune the tree substantially beforehand, thereby making it easier for the tree to survive that length of time.^[6]

If a tree was cut down or broke, and any part of its trunk remains above ground, the orla count does not restart. If it was cut down completely and then regrew from its roots, it becomes subject to orla anew.[7]

6. Layering and the Law of New Shoots

To create a havrakha, or layering, one bends a branch from an established tree, buries the middle section in the ground, and leaves the tip exposed at the place where he wants a new tree to grow. At first, the layered branch draws its nourishment from the original tree. Over time, the buried section develops roots that also nourish the new tree. For orla purposes, as long as the new tree continues to draw nourishment from the original tree, even if most of its nourishment now comes from the new roots formed through the layering, the new tree is considered an extension of the old tree, and the orla count does not begin anew. Even if one layers a third tree from the second, and a fourth from the third, the orla count does not begin for any of them as long as they remain connected to the first tree, since they are still considered extensions of it. If, however, the connecting branch is cut, or that section withers away, one must begin counting the three orla years anew for the layered tree.

If new shoots emerge from beneath the ground, even though they came from the root system of an old tree, then as long as their connection to the old tree is not apparent — for example, when they emerge some distance from it — they are treated as a new tree, and the orla count begins for them (Bava Metzia 119a; MT, Laws of Second Tithe and Fourth-Year Fruit 10:19). If, however, the shoots grow close to the old tree, and it is apparent that they are part of it and emerged from the underground portion of its trunk, one could argue that they belong to the original tree and that the orla count should not begin anew. Nevertheless, since many authorities are stringent and treat even these shoots as a new tree, it is proper to be stringent.^[8]

7. Pots and Nurseries

Orla applies to a tree growing inside a house. Since orla depends on the tree being planted in the ground, having a roof above it does not prevent orla from applying. Likewise, orla applies to a tree planted on a rooftop. Even though the roof separates the tree from the earth, the roof itself is connected to the ground through the walls. It is therefore considered part of the ground, and the tree growing on it is considered planted in the earth (SA YD 294:26).

One who plants a sapling in a perforated pot is considered to have planted it in the ground, and the orla years are counted from then. If one plants a tree in an earthenware pot, even one without holes, the tree is also considered planted in the earth, and orla applies to it, because its roots can break through the earthenware. Even before they do so, they are considered to draw nourishment from the ground. Some maintain that orla applies even to a tree growing in a metal pot, despite the fact that its roots clearly cannot penetrate the metal.^[9]

With modern advances in fertilization and irrigation, many trees are now capable of bearing abundant fruit already in their third year. Since one may not derive benefit from that fruit, and it is costly to leave valuable agricultural land unproductive, farmers developed a practical solution. They keep the trees for about two years in nurseries, in perforated plastic pots, where they occupy little space and cost less to maintain. In the third year, they transfer them to the ground, where they can take root more firmly and then produce abundant fruit in the fourth year, when the fruit is no longer orla.

In practice, because we are concerned for the view that the orla count may not begin in an unperforated plastic pot, two conditions must be met if time spent in nursery pots is to count toward the three orla years according to all opinions. First, the pot must have a hole large enough for a small root, so that it is considered connected to the ground. Accepted practice requires a hole at least 2.5 cm in diameter.^[10] Second, when the sapling is transferred from the pot into the ground, one must take care that the soil clump around the roots does not fall apart. After the fact, even if most of it crumbled, as long as the roots still remain embedded in enough soil to sustain the tree, one need not restart the count. If, however, almost all the clump broke apart, so that even with watering and care the tree would likely not survive for 14 days unless it were replanted, then one must begin counting the three orla years anew.^[11]

8. Trees Subject to Orla

The mitzva of orla applies to fruit trees, not to vegetables. Orla does not apply even to vegetables that grow on perennial shrubs. The key difference between a tree and a perennial vegetable is this: the stem of a perennial vegetable withers each year and regrows from its roots the following year, whereas the trunk and root system of a tree remain in place and become more established from year to year. New branches and fruit then continue to grow from that same enduring structure. This distinction also determines the blessing over the fruit — whether ha-etz or ha-adama. For this reason, one recites ha-adama over bananas. Although the banana plant can grow to about four meters and looks like a tree, it is considered a vegetable because its “trunk” withers, its roots shrivel, and it regrows the following year only from its bulb (Berakhot 40a; following the Geonim; SA and Rema OḤ 203:2–3; Peninei Halakha: Berakhot 8:2).^[12]

Eggplants and peppers require special consideration, because their stems remain intact from year to year. In practice, orla does not apply to them, as they differ fundamentally from trees. They bear fruit already in the first year; in the second year, their yield diminishes in both quantity and quality; and they generally do not continue producing beyond three years. By contrast, the Torah presents a tree as bearing fruit for at least five years; by observing orla, its fruit increases and improves in the fifth year, as it says: “When you come into the Land and plant any tree for food, you shall regard its fruit as closed off. For three years it shall be closed off to you; it may not be eaten. In the fourth year, all its fruit shall be sacred, for praise of the Lord. In the fifth year, you may eat its fruit, so that it may yield its increase to you. I am the Lord your God” (Vayikra 19:23–25). As the Sages said: “This mitzva that you keep will increase its yield for you, for I will bless the fruit you plant in its merit.” R. Akiva would say: “The Torah addressed the evil inclination, lest a person say, ‘I have worked in vain for four years.’ The verse therefore says, ‘so that it may yield its increase to you. I am the Lord’; I am the Lord Who guarantees this and is faithful to keep My promise” (Rashi, citing Torat Kohanim on Vayikra 19:25). Ramban likewise explains that the fruit grown in the third year is scant and poor, and only in the fourth year does it become good and fit to be brought before God as neta reva’i.

On that basis, orla does not apply to papaya and passion fruit either. They bear fruit already in the first year, and by the fifth year their yield has declined. Many of these plants do not even last five years. Some are stringent, but the accepted halakha follows the lenient opinion. For the same reason, orla does not apply to any variety of raspberry or blackberry, as explained in the note. ^[13]

9. Planting a Tree for Purposes Other Than Fruit

If one plants a tree not for its fruit, but for its wood or as a fence, orla does not apply to the fruit that grows on it. Such a tree is not considered a “tree for food,” and the mitzva of orla applies only to a fruit tree, as it says: “When you plant any tree for food, you shall regard its fruit as orla” (Vayikra 19:23). However, the Sages limited this leniency to cases in which it is evident that the tree was planted not for its fruit. If the trees are planted very densely, for example, it is clear that they were meant for firewood. If one prunes the branches in a way that causes them to thicken, it is evident that the tree was planted for lumber. If the precise placement of the trees shows that they were planted as a fence around a yard, orla does not apply to them. If one intended one side of the tree to serve as a fence and the other side to produce fruit, orla does not apply to the fence side, but it does apply to the fruit side (Mishna, Orla 1:1; Yerushalmi, Orla 1:1; SA YD 294:23). If one wishes to eat fruit from the side to which orla does not apply, one must separate terumot and ma’aserot without a berakha (see Yerushalmi, Orla 1:1). If, however, the tree was planted both for fencing or lumber and for fruit, then orla applies to its fruit.

If trees, such as olive trees, are planted for ornamental purposes, orla does not apply to their fruit. However, there is some doubt about trees planted as ornamentals when their fruit also contributes to their appearance, such as pomegranates and date palms. Since orla applies by Torah law, one must be stringent in cases of doubt. Only when it is clear that the fruit itself was not intended to enhance the tree’s appearance does orla not apply to it.

10. Neta Reva’i

Fourth-year fruit has sanctity. There is a mitzva to eat it in a state of purity in Jerusalem, as with ma’aser sheni (see below, 7:9–10). If the owner wishes, he may redeem the fruit onto money, bring the money to Jerusalem, buy food with it, and eat that food there in purity. Since neta reva’i fruit has sanctity, one need not leave leket, shikḥa, or pe’a from it for the poor, nor must one separate terumot and ma’aserot from it (Mishna, Ma’aser Sheni 5:3–4; Yerushalmi, Ma’aser Sheni 5:3–4; MT, Laws of Second Tithe and Fourth-Year Fruit 9:1–4).

Today, since we cannot bring fourth-year fruit to Jerusalem and eat it there in a state of purity, one redeems such fruit onto money or onto food of monetary value, thereby permitting the fruit to be eaten. Even if the fruit is abundant, since we may not eat it today while it retains its sanctity, it has no real value. Nevertheless, it may not be redeemed for less than a peruta. Therefore, one redeems all the fruit onto a coin worth at least a peruta, or onto food worth a peruta. Before redeeming it, one recites: “Blessed are You, Lord our God, King of the universe, Who has sanctified us with His commandments and commanded us regarding the redemption of fourth-year produce.” One then says: “All this fruit is hereby redeemed onto this peruta,” or “onto this food, which is worth a peruta.” The coin or food onto which the sanctity was transferred must then be destroyed, so that no one will mistakenly derive benefit from it (MT, Laws of Forbidden Foods 10:16–17). The details of these laws are explained below, in the laws of redeeming ma’aser sheni (chapter 10, sections 6–8).^[14]

The laws of orla and neta reva’i also apply to Shemita fruit. Fruit that grows during the tree’s first three years has the status of orla and may not be eaten. Fruit that grows in the fourth year may be picked by anyone, but it must be eaten in Jerusalem. Today, it must be redeemed onto a peruta. Field owners must mark such trees during the Shemita year, so that those who enter the field will know not to eat fruit that is orla and to redeem fruit that is neta reva’i. After it is redeemed, care must be taken to finish eating it by the time of bi’ur. If one did not do so, one must perform bi’ur for it, just as one does with all other Shemita produce (MT, Laws of Second Tithe and Fourth-Year Fruit 9:7; Peninei Halakha: Shevi’it 4:5).

The halakhic authorities disagree about neta reva’i in the Diaspora. Some maintain that since a halakha transmitted to Moshe at Sinai establishes that orla applies outside Eretz Yisrael, neta reva’i applies there as well, because the two laws are linked (Rabbeinu Yona; R. Yitzḥak Ha-zaken). Others maintain that neta reva’i is like ma’aser sheni, which applies only in Eretz Yisrael (Rambam). Ideally, in order to satisfy all views, one should redeem neta reva’i in the Diaspora without reciting a berakha (Shakh YD 294:17). Nevertheless, one may rely on the lenient view and not redeem it. Just as fruit whose orla status is uncertain is permitted in the Diaspora, so too, when there is uncertainty about neta reva’i in the Diaspora, the halakha follows the lenient view.^[15]

11. Cases of Uncertainty Concerning Orla

If orla fruit becomes mixed with permitted fruit of the same kind, the entire mixture is forbidden unless the permitted fruit is at least 200 times the amount of orla fruit. The Sages established this measure because teruma, which is forbidden to eat but permitted for benefit, is nullified in a ratio of one to 100, whereas orla and kil’ei ha-kerem, which are forbidden both to eat and to derive benefit from, are nullified in a ratio of one to 200 (Mishna, Orla 2:1).

The 1:200 rule applies when orla fruit itself became mixed with fruit that would otherwise be permitted. If, however, there is uncertainty about particular fruit that someone bought — whether it came from an orla tree or not — the ruling depends on where the uncertainty arose. If the fruit was bought from an orchard or near one, then even though most orchards and trees do not produce orla fruit, the fruit is forbidden. Because the tree or orchard has a fixed location, we apply the rule: kol kavu’a ke-meḥtza al meḥtza dami — anything fixed is treated as though the probabilities were evenly balanced. If, however, the fruit was bought only after it had been removed from its fixed place and brought to the market or to stores, this is an ordinary case of uncertainty, and we follow the majority. In that case, we apply the rule: kol de-parish me-ruba parish — anything separated from a group is presumed to have come from the majority.

This permission to rely on the majority applies only after the fact — for example, when someone already bought fruit and does not know its status, or when one is in a place with no stores that have kashrut certification and reaching such a store would involve considerable trouble. If, however, there is a store with kashrut certification, one must avoid the uncertainty and buy there. Even if the uncertainty is very remote, because the percentage of orla fruit in that produce or in that region is extremely low, one must avoid creating such uncertainty whenever possible. In addition, it is a mitzva to support those who are careful in matters of kashrut. Moreover, when fruit is sold under reliable certification, terumot and ma’aserot are also properly separated.^[16]

1. The Kilayim Prohibitions: General Principles and Rationale

God created distinct species in the world, and in several contexts commanded us not to mix them with one another. The Torah states: “You shall keep My statutes: You shall not breed your animal with a different species; you shall not sow your field with kilayim; and a garment of kilayim, sha’atnez, shall not come upon you” (Vayikra 19:19). It also says: “You shall not sow your vineyard with kilayim, lest the entire yield become forbidden – the seed you sow and the produce of the vineyard. You shall not plow with an ox and a donkey together. You shall not wear sha’atnez, wool and linen together” (Devarim 22:9–11). This category of prohibitions is generally called kilayim, a term meaning “mixture.” In other words, even when each species is permitted on its own, their combination is forbidden. Therefore, the prohibition against cooking meat with milk is also included among the prohibitions of kilayim.

There are seven prohibitions of kilayim: (a) animal kilayim – breeding two different animal species; (b) working two different animal species together; (c) tree kilayim – grafting two different plant species; (d) seed kilayim – sowing two types of seeds together; (e) vineyard kilayim – sowing grain or vegetables near grapevines; (f) garment kilayim – wearing clothing that contains wool and linen together; and (g) meat and milk.

The prohibition of kilayim applies to both plants and animals. In some forms of kilayim, only the act of mixing is prohibited. After the fact, however, one may eat or derive benefit from the result of the mixture. This is true of seed kilayim, tree kilayim, and animal kilayim, whether through breeding or labor. By contrast, in other forms of kilayim, the act of mixing is prohibited, and the resulting product is forbidden for consumption or benefit. This is true of vineyard kilayim and cooking meat with milk. In the case of garment kilayim (sha’atnez), the prohibition is only to wear such a mixture; there is no prohibition against making it for a gentile or for a purpose other than wearing.

Mitzvot dependent on the Land, such as seed kilayim and vineyard kilayim, apply by Torah law only in Eretz Yisrael, within the territory settled by those who came up from Egypt (below, chapter 12, note 2). By contrast, mitzvot that are not dependent on the Land, such as garment kilayim, meat and milk, and animal kilayim, apply in the Diaspora as well. The prohibition of tree kilayim – grafting one species onto another – also applies in the Diaspora. Although this prohibition appears to be dependent on the Land, the prohibited act takes place above ground, not in the ground itself (below, section 5). Since the law of vineyard kilayim is especially stringent, as the mixture is forbidden both for consumption and benefit, the Sages decreed that it is prohibited in the Diaspora as well (below, chapter 4, section 4).

Although we cannot grasp the full depth of the mitzvot, which are divine in origin and rooted far beyond human understanding, some mitzvot have reasons that are more readily understood. These are called mishpatim, or ordinances. Others have reasons that are less understandable to us; these are called ḥukim, or statutes. The mitzva of kilayim belongs to the category of ḥukim, as the verse says: “You shall keep My statutes” (Vayikra 19:19). Rashi likewise explains that these are decrees of the King whose reasons are not revealed. We may suggest that these ḥukim reflect the unique qualities that God implanted within all created beings, qualities that point to the distinct identity and purpose of each creation. The divine statute, whose secret we cannot fully fathom, concerns the meaning and unique purpose of every species God created. Through the prohibition of kilayim, we are commanded to preserve the special and dignified place of every species, not to blur its uniqueness by mixing it with another species (Ramban and Maharal to Vayikra 19:19; Sefer ha-Ḥinukh 244). Similarly, the Sages said: “‘You shall keep My statutes’ – the statutes that I already engraved for you in the nature of creation, you must now observe” (Kiddushin 39a).

The word kilayim is related to kele, which means prison. The mixture imprisons the distinctive qualities of the species, preventing them from being expressed properly once they have been mixed with another species (Zohar III 86a; Rabbeinu Baḥya). With seed kilayim and vineyard kilayim, the prohibition applies even when the species merely grow near one another, even though the species themselves do not actually mix or merge. These prohibitions apply specifically in Eretz Yisrael because in the Land, the sanctity of creation is more fully revealed. As a result, the uniqueness of each species is more apparent there, and its special and dignified place must be preserved.^[1]

2. The Prohibition Against Animal Kilayim

One may not breed a male of one species with a female of another, as the verse states: “You shall keep My statutes; you shall not breed your animal with a different species” (Vayikra 19:19). Although the verse says “your animal,” it refers to all living creatures, including birds and sea creatures. The Torah mentions animals by way of example because domesticated animals are commonly kept by people (Bava Kama 54b). By Torah law, one may not perform the mating directly, meaning actual insertion of the male’s organ into the female. The Sages further prohibited bringing about mating indirectly, such as by positioning the male atop the female in a way that leads them to mate. However, one may place different species together in the same enclosure. If they mate on their own, one need not separate them, since placing them in the same enclosure is not considered an act that caused the mating (SA YD 297:2–3).

One may not breed two species of domesticated or wild animals. If one transgressed and did so, however, one may derive benefit from the offspring. The best-known hybrid is the mule, born of a male donkey and a mare. Mules have long been prized for carrying loads and plowing. Since the prohibition is only to bring mules into being, one may purchase and use them.

Breeding two different species is prohibited, but breeding two breeds of the same species is permitted. Therefore, one may breed bulls and cows of different breeds with one another. Similarly, one may breed different breeds of sheep, cats, or dogs. However, one may not breed two different species, even if they are relatively similar to one another. The definition of a species is determined by the overall traits and form of each species, as explained below, section 4. As a general rule, the inability to produce fertile offspring is a sign that two animals are different species. Usually, breeding two different species produces no offspring at all. In the rare cases where offspring are born, as with a donkey and a mare, the offspring is sterile. If two types can produce fertile offspring, it appears that they are not two separate species, but two varieties within a single species. In that case, there is no prohibition against breeding them together.^[2]

3. Working Two Animal Species Together

In addition to the prohibition against breeding two species with one another, the Torah forbids working with two different species together. For example, one may not plow with an ox and a donkey together or harness a horse and a donkey to the same wagon. The verse states: “You shall not plow with an ox and a donkey together” (Devarim 22:10). The Torah uses the example of an ox and a donkey because these are domesticated species commonly put to work together. However, the prohibition applies to any combination of two animal species used together for labor. The prohibition is not limited to the driver who harnesses the horse and donkey to the wagon and directs them; anyone who assists in the work violates it as well. Even one who only calls out to drive them forward violates a Torah prohibition, since he causes them to continue pulling the wagon or plow (SA YD 297:11, 13–14).^[3]

Jews alone are bound by this prohibition. If a Jew hires a gentile to transport merchandise to another city, and the gentile chooses to use a wagon harnessed to a horse and a donkey, the Jew violates no prohibition, since he has no stake in that arrangement (Arukh ha-Shulḥan YD 297:21). However, a Jew may not sit in a wagon that a gentile drives with a horse and donkey, because the passenger becomes a partner in the labor. If he were not sitting in the wagon, the driver would not command the animals to pull it (SA YD 297:12).

The prohibition of kilayim applies only when the two species are tied together. Therefore, one riding a horse may hold a rope attached to a dog. However, he may not tie the dog’s leash to the horse’s saddle, since doing so connects the two animals. At times, the dog may move ahead of the horse and pull it forward, causing the rider to violate the prohibition of animal kilayim (Arukh ha-Shulḥan YD 297:19).

Although we cannot fully grasp the depth of the mitzvot, especially the ḥukim, the Sages nevertheless sought to understand their reasons. Rambam explains that this prohibition is meant to keep different species apart, so that people will not be led to breed one species with another (Moreh Nevukhim 3:49). Sefer ha-Ḥinukh explains that the prohibition prevents animal suffering. Each species naturally prefers the company of its own kind and suffers when paired with another species. This is especially true during labor, because animals of different species do not have equal strength; when they do not pull the wagon or plow evenly, they suffer (Sefer ha-Ḥinukh 550).

4. The Prohibition Against Grafting Trees

One may not graft two species of trees onto one another, as the verse states: “You shall keep My statutes; you shall not breed your animal with a different species; you shall not sow your field with kilayim” (Vayikra 19:19). Just as the first clause prohibits breeding two animal species with one another, so too “you shall not sow your field with kilayim” prohibits grafting two plant species onto one another. This includes grafting different species of trees or vegetables, as well as grafting a tree onto a vegetable or a vegetable onto a tree. All non-fruit-bearing trees are considered one species. Therefore, one may not graft a fruit tree onto a non-fruit-bearing tree. One may, however, graft one non-fruit-bearing tree onto another, since for this law they are all considered one species. Their defining feature is that they do not produce fruit, and that feature classifies them together as a single species (SA YD 295:1–3; Rema YD 295:6).

This prohibition applies in the Diaspora as well. Although at first glance grafting appears to be dependent on the Land, the prohibited act itself is performed above the ground. It therefore resembles the prohibition of animal kilayim, which is mentioned next to it in the verse (Kiddushin 39a). The two laws are similar in another respect as well: although one may not breed animals or graft trees, the resulting offspring or produce may be eaten or used even from the outset.

Grafting is used to combine the desirable traits of two species or varieties of trees. Trees that bear abundant, flavorful fruit often have weaker root systems and are more susceptible to disease and death. Hardy, resilient trees, by contrast, generally bear little fruit, and their fruit is less flavorful. To address this, growers graft one onto the other. They plant a cutting from a hardy tree in the ground; this is called the rootstock. The rootstock is cut in a particular way, and a branch from a tree that bears high-quality fruit, called the scion, is attached to it. The two parts are bound together until they fuse and then continue growing as a single tree. The roots and lower trunk belong to the hardy species, while the upper trunk, branches, and fruit belong to the species that bears abundant, flavorful fruit. Thus, even though the two trees have been grafted and joined, each part continues to function according to its own nature: the rootstock draws nourishment from the ground through its roots, while the scion produces fruit according to its own nature. As a result, there is almost no difference between fruit that grows on a scion grafted onto another species and fruit that grows on a scion rooted naturally in the ground.

If the rootstock and scion are from two different species, grafting them is a Torah prohibition for which one is liable to lashes. If they are different varieties of the same species, grafting them onto one another is permitted. Therefore, one may graft a large, red, sweet apple variety onto a small, green, sour apple variety, since both are apple varieties. However, one may not graft a peach tree onto an almond tree, because they are two different species. For the laws of kilayim, species are defined broadly. Classification depends on the tree’s full range of visible characteristics: the fruit’s form and taste, the branches and leaves, and the growth pattern. Therefore, trees classified by common usage or by scientific taxonomy as two species may nevertheless be considered one species according to halakha. When the Jewish people lived in the Land, and the Great Sanhedrin resolved every question and uncertainty, the traditional classification of species for the laws of kilayim was known and clear. Over time, however, the many exiles eroded that knowledge, and doubts arose about the status of various trees that are now difficult to resolve.^[4]

5. Grafting and Hybridization

Prohibited tree grafting consists of joining two tree species to one another in such a way that each part retains its own qualities, with no genetic merging between the two parts. By contrast, cross-pollinating two species is permitted. Every fruit-bearing plant produces flowers, and in the flower are male stamens and a female ovary. Through insects, butterflies, and wind, pollen from the male stamens reaches the ovary and the female ovules within it. Through this process, fruit is formed, containing the seed from which another tree can grow. If pollen from the male stamens is taken from a tree of one species and brought together with the female ovary of another species, a hybrid of two different species is created, and the fruit that grows will have genetic traits shared by its two “parents.” Yet each hybridization will yield a somewhat different type of fruit, because each time different components of each species’ genetic sequence are expressed, creating a new blend.

Usually, cross-pollinating two species does not succeed: pollen from the male stamens does not fertilize the ovules in the ovary, and even when fertilization occurs, the fruit produced is usually poor. Sometimes, however, the union succeeds and produces fruit with a distinctive taste, or a tree with special qualities, such as the ability to grow in a climate in which it previously could not survive. To this end, many scientists work to create numerous hybrids. Some rabbis maintain that just as one may not graft two tree species onto one another, one may not cross-pollinate them with one another (Shevet HaLevi 9:224). The primary halakhic position, however, is that the Torah forbade only the act of grafting two different trees onto one another, where they live together contrary to their natural order; it did not forbid cross-pollination, which occurs before the tree itself comes into being. Furthermore, a stamen on its own is not a species, since it cannot grow by its own power; likewise, the ovule in the ovary is not a species. Their hybridization is therefore not prohibited. All the more so, there is no prohibition of grafting in genetic engineering, which joins genetic material from one species with that of another (see also R. Yisraeli, Ha-Torah ve-ha-Aretz 3; Kerem Shlomo 2:1; R. Ariel, Teḥumin 33).

6. Bnei Noaḥ and the Laws of Kilayim

According to most Rishonim and Aḥaronim, the prohibitions against grafting trees and breeding animals of different species apply to Bnei Noaḥ as well, although they are not among the Seven Laws of Bnei Noaḥ. The verse states: “You shall keep My statutes” (Vayikra 19:19), and the Sages derive from this: “The statutes that I already engraved for you” – even before the giving of the Torah – “you must now keep.” Similarly, the Torah states: “The earth brought forth vegetation: seed-bearing plants of every kind, and trees of every kind bearing fruit with the seed in it. And God saw that it was good” (Bereishit 1:12). From here we learn that these statutes are binding on Bnei Noaḥ as well (Sanhedrin 60a; She’iltot; Behag; Rambam; Riaz; Vilna Gaon; Arukh ha-Shulḥan; Rav Kook).

Others disagree and maintain that Bnei Noaḥ are not prohibited from grafting trees or breeding different animal species (Ritva, Rosh, and Radbaz). Even according to this view, however, a Jew may not ask a gentile to graft his tree or breed his animal. Just as a Jew may not ask a gentile to violate Shabbat on his behalf, he likewise may not ask him to perform other Torah prohibitions involving his property.

Even according to the stringent view, the prohibition may apply to Bnei Noaḥ only when the grafting is certainly prohibited. However, when there is uncertainty about the graft’s halakhic status – for example, when the rootstock and scion may be two varieties of the same species – Bnei Noaḥ are not prohibited from performing the graft (see Mishpat Kohen 13).^[5]

7. May One Plant or Maintain a Grafted Tree?

As noted, although one may not graft two tree species together, the fruit produced by such grafting is permitted from the outset. The practical question is what may be done after a prohibited act of grafting has already been performed. May one care for the grafted sapling and water it so that it continues to grow? This question arises frequently. Most pear trees, for example, are grafted in a prohibited fashion, and prohibited grafting is also common among plum and peach trees. The question, then, is whether one may plant a sapling that was produced through prohibited grafting in a nursery. If it has already been planted, may one continue caring for it, or must it be uprooted?

Some maintain that the prohibition is limited to grafting two different species together. Once the graft has been made, however, there is no further prohibition against maintaining the grafted tree. Therefore, if a sapling was grafted in a nursery, one may even plant it in the field and tend to its growth. According to this view, tree grafting is similar to animal kilayim: the prohibition is only to breed an animal of one species with an animal of another. Afterward, however, one may raise and use the offspring.

Many poskim, however, rule that one may not maintain a grafted tree (SA YD 295:7). They disagree, though, about the scope of this prohibition. According to one view, one who has a grafted tree in his field must uproot it. According to another, one may not weed around it or prune it to improve its growth but may leave it in the field untended. A third view maintains that the prohibition applies only until the rootstock and scion have fused. Once they have fused, one may maintain the grafted tree and even plant it.

In practice, some rely on the lenient view that the entire prohibition is limited to the act of grafting. According to this position, even before the graft has fully fused, one may plant the grafted sapling and tend to its growth. The halakha, however, follows most poskim: one may not maintain the grafted sapling until the graft has fused. After that point, one may plant it and care for it. Ideally, one follows the stringent view and refrains from maintaining a grafted tree even after the graft has fused. When there is uncertainty whether the grafting was prohibited – that is, whether it involved two distinct species, or was permitted because it involved two varieties of the same species – one may be lenient and maintain it.

When purchasing a fruit tree, one must verify that it was not grafted in a prohibited manner. Even according to the lenient authorities who permit planting a grafted sapling, buying from someone who performs prohibited grafting assists those who violate the prohibition. Since these laws are complex, one may rely only on a seller who is both knowledgeable in these laws and God-fearing, or on a nursery under reliable kilayim supervision.^[6]

01. The Prohibition Against Seed Kilayim

The Torah prohibits sowing two types of seed together in a field in Eretz Yisrael. Each type must be sown on its own, as it says: “You shall keep My statutes… You shall not sow your field with kilayim” (Vayikra 19:19). The word kilayim means “mixture.” This prohibition includes edible grains, legumes, and vegetables. Plant species grown for ornamentation or medicine, however, are not included.

The prohibition against seed kilayim applies to annual crops: grain, legumes, and vegetables. There is no prohibition against planting different species of trees together, nor against planting trees together with an annual crop. Even when trees are intermingled, their size makes it clear that each tree has its own distinct place. The annual crops planted among them likewise have their own place, since trees grow upward and their roots spread far outward, leaving room for the annual crop to grow among them.

One who waters, fertilizes, weeds, or otherwise assists the growth of kilayim violates a Torah prohibition punishable by lashes. Even when kilayim grew on its own in his field, as long as he wants them there – or it appears as though he wants them there – he must uproot them, for one may not maintain kilayim in one’s field (MT, Laws of Kilayim 1:1–3).

If one deliberately sowed kilayim, the produce may nevertheless be eaten. The prohibition is against sowing and cultivating kilayim; eating what grows from them is not prohibited (MT, Laws of Kilayim 1:7). Only with vineyard kilayim does the resulting produce become forbidden to eat.

The prohibition against seed kilayim applies in Eretz Yisrael. Even on land owned by a gentile, a Jew may not sow kilayim. In the Diaspora, however, a Jew may sow seed kilayim, because the verse speaks of “your field,” and only Eretz Yisrael is considered “your field” for this purpose. The Sages did not prohibit seed kilayim there either; they prohibited only vineyard kilayim in the Diaspora, because it is more severe: one may neither eat its produce nor derive benefit from it (see below, section 7).

In Eretz Yisrael, it is also prohibited to sow two species together in a pot. If the pot is perforated, it is considered connected to the ground, and the prohibition applies by Torah law. If it is not perforated, it is detached from the ground, and the prohibition is rabbinic.^[1]

02. The Concern of Marit Ayin in Seed Kilayim

By Torah law, seed kilayim is prohibited when a person sows two species together or willingly maintains them together. If they grew in his field without his wanting them, he has not violated a Torah prohibition. Nevertheless, because of marit ayin, the appearance of wrongdoing, the Sages prohibited a field owner from leaving kilayim in his field even when he does not want them there. Since the field is open and visible to all, passersby may think that the owner does not care about observing the mitzvot, and this would desecrate God’s name.

Therefore, if one wants to sow his field with wheat and finds that barley seeds have become mixed in with the wheat, he may do so only if the barley remains below a certain threshold. If the barley is not enough to produce one twenty-fourth of the field’s yield – 1/24, or 4.16% – he may sow the mixture as it is. With such a small amount, there is no concern for marit ayin, since anyone who sees the field will understand that the barley is growing there against the owner’s will.

Although one may not intentionally sow even a single barley seed in a wheat field, this applies only when the barley was deliberately added. If one intentionally mixed even one barley seed into the wheat, he may not sow the wheat unless he first removes the barley seed. If, however, the barley became mixed in unintentionally, he does not want it there, and removing it would be burdensome, he may sow the mixture as it is, provided the barley is less than one twenty-fourth of what will grow in the field. At such a small proportion, there is no concern for marit ayin, since anyone who sees the field will understand that the barley is growing there against the owner’s will. If the barley is enough to produce one twenty-fourth of the field’s yield, he must either reduce the barley or add wheat until he is certain that the barley will produce less than one twenty-fourth of the growth in the field.

The same rule governs a field that was sown with one species and later has another species growing alongside it. The determining factor is whether he wants the second species to remain. If he does, the mixture is kilayim, and he must uproot the second species entirely. If he does not want it there, and it makes up less than one twenty-fourth of the field’s growth, he need not reduce it. If it reaches one twenty-fourth, he must reduce it until it is less than that amount.^[2]

Because this mitzva is important and those who violate it cause a grave desecration of God’s name, every year on Rosh Ḥodesh Adar, when grain and vegetables were beginning to sprout, the agents of the beit din would urge the Jewish people to be careful about kilayim (Mishna, Shekalim 1:1).

On the fifteenth of Adar, the agents of the beit din would inspect the fields. If they found kilayim, they would uproot the minority species and place it before the owner’s animals. The field owners benefited twice: their fields were weeded, and their animals were fed. They therefore stopped bothering to remove the kilayim themselves. The Sages then enacted that the agents would uproot the kilayim and leave it on the roads, where any animal could eat it. Still, because the field owners were happy that their fields had been weeded, they did not bother to uproot the kilayim. When even this did not solve the problem, since owners still benefited from the weeding, the Sages enacted that the agents of the beit din would declare everything growing in any field where kilayim was found ownerless. From then on, field owners took care to avoid kilayim (Mo’ed Katan 6b). Once the agents of the beit din declared the kilayim ownerless, the field owner no longer violated the prohibition because of it, since the prohibition against maintaining kilayim does not apply to ownerless growth.

03. The Required Separations for Seed Kilayim

The basic principle in the laws of seed kilayim is that two species may be planted near one another when they remain visibly distinct, but not when they appear mixed together. The larger the field, the greater the required separation, so that the distinction between the species remains recognizable. The required separation also depends on the density, size, and length of the plants’ leaves: grain, whose stalks grow tall, requires a greater separation, while vegetables generally require a smaller one, except for vegetables with especially large leaves.

Vegetables: By Torah law, one must leave one tefaḥ – approximately 8 cm – between one vegetable species and another. The Sages extended the required separation to one and a half tefaḥim – approximately 12 cm. If that distance was left between the two species, there is no prohibition against kilayim even if their branches later grow until they touch, since the stems emerging from the ground remain properly separated. There are a few exceptions, such as gourds, whose leaves are especially large and tend to intertwine with neighboring species. In such cases, one must ensure that the leaves of the two species do not touch. These rules apply to beds in a garden. Two vegetable fields, however, must be separated by a square area one ama by one ama – approximately half a meter by half a meter. Along the rest of the boundary between the fields, it is proper to leave a gap of one tefaḥ.^[3]

Grain: Since grain is normally sown over large areas, greater separation is required. By Torah law, the required distance is one ama. The Sages, however, ruled that this distance is adequate only for small plantings less than one ama wide. For grain sown in medium-sized plots, known as a meishar, whose width is at least one ama, the separating area must begin with a square of two amot by two amot – approximately one meter by one meter – and may then taper diagonally, as illustrated below, until only a minimal gap remains between the fields.

When grain is sown in large fields, as is usual, the required separation is a beit rova, a square of about five meters by five meters. Along the rest of the boundary, it is proper to leave a one-ama gap running the length of the two fields.^[4]

Authorities disagree whether legumes are treated like grain or like vegetables. Therefore, one must leave one ama between the two plantings, regardless of the field’s size.^[5] When grain is sown next to vegetables or legumes, or vegetables are sown next to legumes, the required separations are more complex and depend on the size of the field. In any case, the requirement is no stricter than for grain.

If a partition ten tefaḥim high – approximately 80 cm – stands between two fields, no further separation is needed. This is true even of a reed partition, provided that no gap between reeds exceeds three tefaḥim; the partition itself separates the fields. Even if the roots of the two species are known to intertwine underground, there is no kilayim prohibition so long as the partition creates a visible separation. Similarly, a road four amot wide – about 1.84 meters – or a plowed strip of the same width separates the fields, so the large five-by-five-meter beit rova separation is not required.

04. Vineyard Kilayim: A Distinct and Stricter Prohibition

Although vineyard kilayim can be viewed as a particular case of seed kilayim, in practice it has halakhot of its own. This shows most vividly in the produce. Seed kilayim prohibits the sowing, but the crops that grow may still be eaten and used; what grows from vineyard kilayim, by contrast, is forbidden to eat and even to derive benefit from.

One may not sow grain or vegetables alongside grapevines, nor may one plant a grapevine alongside grain or vegetables. If one did so, both crops become forbidden; one may neither eat them nor derive benefit from them, as it says: “You shall not sow your vineyard with kilayim, lest the full yield – the seed you sow and the produce of the vineyard – become consecrated” (Devarim 22:9). In this context, tikdash means that the produce is consecrated for destruction – forbidden for any benefit. “The full yield of the seed you sow” refers to the grain or vegetable, while “the produce of the vineyard” refers to the grapes. Even the grain’s straw and the vines’ wood become forbidden; they must be burned or otherwise destroyed so that no one mistakenly benefits from them (see above, chapter 2, note 3). Because one may not derive benefit from them even as they are being destroyed, one may not burn them to heat an oven or stove (MT, Laws of Kilayim 5:7). The prohibition of vineyard kilayim applies by Torah law in Eretz Yisrael and by rabbinic law in the Diaspora (see below, section 7).

By Torah law, the prohibition of vineyard kilayim applies when grapevines grow alongside the five grain species, legumes, or vegetables. It does not apply, however, to tree species, even small ones. As a rule, any plant whose berakha is ha-etz is not included in the prohibition of vineyard kilayim, while any plant whose berakha is ha-adama is included (see above, 2:8).

This includes spices over which ha-adama is not recited in practice, since they are not eaten on their own (Peninei Halakha: Berakhot 8:14). If they are plant species whose berakha would be ha-adama if they were eaten on their own, they are included in the prohibition of vineyard kilayim.

The Sages also extended the prohibition to grasses and vegetables commonly used as animal fodder. Plants that are not commonly fed even to animals are not included in the prohibition (Levush YD 296:2).

Authorities disagree about plants grown for fragrance. Some authorities prohibit them rabbinically, while others permit them. In practice, it is best to be stringent, but one who wishes to be lenient may do so. Ornamental plants, by contrast, are not prohibited. Therefore, one may plant grass and flowers beneath a grapevine, provided they are not commonly fed to animals, even if they also have medicinal uses.^[6]

05. When the Produce Becomes Forbidden

The prohibition of vineyard kilayim includes not only sowing the forbidden mixture but also maintaining it (Mishna, Kilayim 8:1). Thus, even if a person did not sow grain in his vineyard, if even a single grain stalk grows there, he must act quickly to destroy it, because one may not maintain kilayim in a vineyard.

Sowing and maintaining differ, however, in when the produce becomes forbidden. If one sows a grain stalk in his vineyard, the stalk and the surrounding vines become forbidden for benefit as soon as it takes root. If, however, one merely finds a grain stalk that grew in his vineyard, it and the vines become forbidden for benefit only if it continues to grow by one part in two hundred. Nevertheless, he must destroy it immediately, because even one who is negligent and maintains it for even a moment violates the prohibition (Mishna, Kilayim 5:6; Pesaḥim 25a; MT, Laws of Kilayim 5:21–22; 6:1).^[7]

When do the vines become forbidden for benefit? Only when grapes are present on the vines and are still growing and ripening. This period begins when the grapes reach the boser stage, meaning that their form is recognizable and they are at least the size of a white bean, and it continues until the grapes are fully ripe. If there are no grapes in the vineyard, or if the grapes have either not yet reached the size of a white bean or have already fully ripened, grain or vegetables growing nearby do not render the vines forbidden for benefit. The grain or vegetables themselves, however, do become forbidden.

When does the grain become forbidden? From the time it takes root in the ground until the kernels fully ripen. Therefore, if the grain has already finished ripening and a vine bearing grapes at the forbidden stage is bent over it, the entire vine becomes forbidden, but the grain does not become forbidden (Mishna, Kilayim 7:7).^[8]

If the wind bent a person’s vine over his grain, he must separate them immediately. If there is concern that they will become mixed again, he must cut the vine branches or erect a fence to prevent it from happening again. If he was negligent and they remained mixed until one of the two increased by one part in two hundred, they become forbidden. If, however, circumstances beyond his control kept him from separating them in time, they do not become forbidden (Mishna, Kilayim 7:7; R. Yitzḥak b. Malki Tzedek and R. Shimshon to Mishna, Kilayim 7:7; MT, Laws of Kilayim 5:11; Kesef Mishneh and Mahari Kurkus to MT, Laws of Kilayim 5:11).

A person cannot render someone else’s property forbidden. Therefore, if one caused his vine to spread over another person’s grain, his vine becomes forbidden, but the other person’s grain remains permitted. If he caused another person’s vine to spread over his own grain, his grain becomes forbidden, but the other person’s vine remains permitted. If he caused one person’s vine to spread over another person’s grain, both remain permitted. However, as soon as the owner of either the vine or the grain becomes aware of the kilayim, he must act quickly to separate them. If he is negligent until one of them increases by one part in two hundred, his own portion also becomes forbidden.

The person who actively mixed the kilayim by hand is treated more stringently: for him, even property that is not his becomes forbidden. Moreover, if a person passes by another person’s vineyard, sees grain stalks growing there, and knows that the owner wants them to remain, he must uproot them. Similarly, a worker employed there must uproot the kilayim. If they do not do so, the vine and grain that grew there become forbidden to them for benefit. The vineyard owner, however, has not violated the prohibition. Only once he learns of the kilayim must he act quickly to uproot the grain stalks. If he is then negligent and they continue growing by one part in two hundred, they become forbidden to him and to all Jews (Mishna, Kilayim 7:4; MT, Laws of Kilayim 5:8–9, 21; Taz YD 296:3).

06. Required Distances for Vineyard Kilayim

The mitzva of kilayim requires that grain and vegetable species remain separate from grapevines. The Torah gave the Sages authority to determine, according to their judgment, what is considered mixed and what is not. What the Sages define as a prohibited mixture is therefore included in the Torah prohibition. There are three main situations in the laws of vineyard kilayim, listed here in ascending order of severity: 1) near a single vine; 2) near a vineyard; and 3) inside a vineyard.

A single vine: One who wishes to sow grain or vegetables near a single vine must keep them six generous tefaḥim away, approximately 47 cm. This is the area needed for the vine’s bed and the workspace around it. Grain or vegetables may not grow beneath the vine’s canes either. Thus, if a grain stalk grew beneath one of the canes, leaves, or clusters growing from the vine – even one hundred amot from the vine’s trunk – and the owner was negligent and did not uproot it, the stalk and the entire vine become forbidden for benefit, as explained above in section 2. If there is doubt whether the stalk is beneath the vine, its position is determined by a plumb line. Since vine canes often extend over a large area, one must ensure that no grain or vegetables grow beneath them at any point along their length.

Vines are commonly trained along poles or cords, with the canes expected to grow along them. The Sages therefore decreed that grain or vegetables may not grow even beneath the part of a pole or cord that the cane has not yet reached, since the cane is expected to extend there. After the fact, however, as long as the grain or vegetables were not actually beneath the vine itself, they do not become forbidden (MT, Laws of Kilayim 6:11–12, 15).

A vineyard is a grapevine planting arranged precisely according to the accepted method of cultivation. Since a vineyard has halakhic significance, one who sows grain or vegetables within four amot of it is considered to have sown them together with the vineyard, thereby violating the prohibition of kilayim. This distance was set at four amot, approximately 188 cm, because that was the space needed for vineyard work in earlier times. Vineyards were plowed with oxen, and at harvest time the grapes were brought from the vineyard to market by cart; both the oxen and the carts required this working space.

For vines to be considered a vineyard, they must form at least one of the following arrangements: two facing rows, with three vines in each row, as follows:

or five vines arranged as “two opposite two, with one extending like a tail.” Rambam illustrates this second arrangement as follows:

R. Shimshon illustrates it this way:

If the vines do not form straight rows, even if there are many of them, they are treated a

individual vines.^[9]

If one sows grain or vegetables within four amot of a vineyard, the portion of the vineyard equivalent to a small vineyard becomes forbidden – that is, the five vines closest to the kilayim, arranged in vineyard formation. If there are additional vines within four amot of the kilayim in any direction, they too become forbidden. One must also be careful with any vine cane that extends beyond the four-ama zone surrounding the vineyard. It is treated like a single vine, so grain or vegetables may not grow beneath it; if they do, both that vine and everything growing beneath the cane become forbidden.

An aris has the same status as a vineyard. An aris is formed by at least five vines planted in a straight row and trained along poles or wires, allowing them to receive more sun and air and produce more abundant, higher-quality grapes. If the kilayim are within four amot of the aris – whether near the vine trunks or near the poles or wires on which the vines are trained – the five vines facing the kilayim become forbidden.

A fence ten tefaḥim high, approximately 80 cm, separates the vineyard from the field. Once such a fence stands between them, one may sow grain or vegetables on the other side without any additional distance (MT, Laws of Kilayim 7:15). This is true even if the vine’s roots extend beneath the grain, because vineyard kilayim is defined by the visible appearance of mixture, not by the underground spread of roots. Since the fence makes the vineyard and field appear separate, the plants are not considered mixed.

Inside the vineyard: If one sowed kilayim inside a vineyard, or if kilayim grew there on its own and the owner was negligent and did not uproot it, the mixture is more apparent because it is inside the vineyard itself, and its laws are therefore far more severe. The affected area is measured by the reach of the roots’ nourishment: sixteen amot in every direction, plus an additional four amot for the vineyard’s work area. Thus, every vine within less than twenty amot of the kilayim becomes forbidden for benefit (MT, Laws of Kilayim 6:1–2).

07. The Diaspora and Kilayim of Non-Jews

The Torah prohibition of seed kilayim and vineyard kilayim applies only in Eretz Yisrael. Regarding seed kilayim, the verse states: “You shall keep My statutes… You shall not sow your field with kilayim…” (Vayikra 19:19). Regarding vineyard kilayim, it states: “You shall not sow your vineyard with kilayim” (Devarim 22:9). The terms “your field” and “your vineyard” refer to the field and vineyard of the Jewish people, which are in Eretz Yisrael. Nevertheless, because vineyard kilayim is especially severe – its produce is forbidden both to eat and to derive benefit from – the Sages extended the prohibition to the Diaspora as well. They established, however, that in the Diaspora the prohibition applies only to cases that all authorities agree are forbidden by Torah law in Eretz Yisrael, both with respect to sowing and with respect to benefit (Kiddushin 39a).

Therefore, in the Diaspora, vineyard kilayim is prohibited only when one sows at one time a grape seed together with two other seed species that are themselves kilayim with one another – for example, two types of grain, two types of vegetables, or one vegetable species together with one grain species.

Although in Eretz Yisrael the Torah prohibition of vineyard kilayim applies even when one sows a single grain stalk next to a grapevine, and one who knowingly eats what grows there is liable for lashes, one is liable for sowing vineyard kilayim only in the narrower case: when he sows a grape seed together with two seed species that are kilayim with one another. Therefore, in the Diaspora, both the prohibition of sowing vineyard kilayim and the prohibition of deriving benefit from what grows apply only in that case. One may, however, sow grain in his vineyard in the Diaspora and eat what grows there (Rema YD 296:69).^[10]

Although a non-Jew may sow kilayim in his vineyard in Eretz Yisrael, a Jew may not instruct him to do so (MT, Laws of Kilayim 8:13). Furthermore, by Torah law, a Jew may not derive benefit from grapes, grain, or vegetables that grew as kilayim in a non-Jew’s vineyard (Tosafot, Kiddushin 36b, s.v. kol; Rosh). Therefore, one may not buy grapes or vegetables from non-Jews near the vineyards where they were grown, since they may have been grown in violation of the prohibition. If one transgressed and bought them, he may not derive benefit from the produce. Since the doubt arose while the produce was still near its fixed place of origin, it is forbidden both to eat and to derive benefit from.

If, however, one buys in the market or in stores grapes or vegetables grown by non-Jews, then the doubt arose only after the produce had already separated from its fixed place. We therefore follow the majority, and the produce may be eaten. This ruling applies be-di’avad – for example, when one has already bought the produce and does not know its status, or when one is in a place with no kashrut-certified stores, and reaching such a store would require significant effort. If, however, there is a kashrut-certified store, one must avoid the doubt and buy there. Even when the concern is very remote, one must avoid entering a doubtful situation whenever possible. In addition, it is a mitzva to strengthen those who are careful in matters of kashrut. Moreover, when produce bears kashrut certification, terumot and ma’asrot will also have been separated properly, as explained above, 2:11.^[11]

08. The Reason for the Mitzva

The prohibition of vineyard kilayim is unique. In addition to the prohibition against mixing grain or vegetables with a grapevine, the produce that grows from such a mixture is itself forbidden, both to eat and to derive benefit from, as it says: “You shall not sow your vineyard with kilayim, lest the full yield – the seed you sow and the produce of the vineyard – become consecrated” (Devarim 22:9). Here, “become consecrated” does not refer to positive holiness. It means that the produce has been designated and set aside for a particular purpose. Usually, such designation is holy and exalted; at times, however, people dedicate themselves to sin, as in the case of a prostitute, who is called a kedesha (Bereishit 38:21). So too, the fruit of vineyard kilayim, having been set apart through sin, becomes consecrated to impurity and is forbidden to the entire Jewish people.

Vineyard kilayim may be treated so severely because it involves the vineyard, and wine has extraordinary power – for good and for harm. On the one hand, song and blessing are recited over wine. On the other hand, it can degrade a person and cast him into the depths of sin. For this reason, a special mitzva of nezirut was established in relation to wine: one who fears that wine may pull his heart toward evil, or hinder his growth in holiness, takes a vow to abstain from it. Indeed, an entire tractate of the Talmud is devoted to this subject: Nazir.

Since wine can sway a person’s judgment, the Torah forbids kohanim to drink wine while serving in the Temple. Similarly, one who has drunk wine may not pray (Peninei Halakha: Prayer 5:11). This same concern helps explain why the Torah treated vineyard kilayim more severely than other forms of kilayim: anything connected to wine requires special care. Wine should be used for the joy of a mitzva, not for unrestrained indulgence or escape from responsibility (see Peninei Halakha: Berakhot 7:1–2).

There is another dimension as well: grain, legumes, and vegetables are essential to human survival. Although eating them does not involve especially intense desire, a person cannot live without them. Therefore, one must work diligently to cultivate them and eat them regularly. Wine, by contrast, is not necessary for survival, but it brings great joy and is meant to serve the joy of a mitzva. This helps explain why blurring the boundary between these two categories is dangerous. If a person treats wine like grain, drinking it as a regular staple, he may become enslaved to his desire and fall into alcoholism. Even if he does not become addicted, excessive daily drinking causes wine to lose its special role in the joy of a mitzva. Conversely, if a person treats grain like a vine, as though it were not essential, he will become lazy, and thorns will grow in his field instead of grain (see Shemen Ra’anan, p. 333, citing Maran Rav Kook).

01. The Mitzva

The Torah commands us not to wear a garment made of wool and linen, as it states: “You shall observe My statutes: you shall not mate your animal with a different species, you shall not sow your field with two kinds of seed, and a garment of mixed kinds, sha’atnez, shall not come upon you” (Vayikra 19:19). It also states: “You shall not wear sha’atnez, wool and linen together” (Devarim 22:11).

The wool included in this prohibition is sheep’s wool. Male sheep are called rams, and females are called ewes. The fleece of other animals is not included, because it is not called simply “wool” but is identified by a qualifying term. Thus, the prohibition does not apply to camel wool, goat wool (such as cashmere), rabbit wool (such as angora), or alpaca wool. In practice, from antiquity to the present, most of the world’s wool has come from sheep, which naturally produce abundant, high-quality fleece and are readily domesticated.

Flax is a plant with a single long stalk containing fibers that can be made into strong thread. With special processing, these fibers can be spun into fine thread and woven into attractive white garments. The prohibition of sha’atnez applies specifically to flax and not to fibers derived from other plants, such as hemp or cotton. In earlier times, most clothing was made of wool or linen; some therefore maintain that when the Torah uses the word “garment” without qualification, it refers to a garment made of wool or linen (Menaḥot 39b).

The prohibition of sha’atnez applies to wearing a garment containing both wool and linen. It does not prohibit wearing two separate garments, one made of wool and the other of linen. One may therefore wear wool pants with a linen shirt, or a wool robe fastened with a linen belt. As long as the wool and linen garments are not joined by sewing or a permanent knot, there is no prohibition (below, 6).

The prohibition applies to wearing garments containing wool and linen, not to making sha’atnez fabric for other purposes. It may therefore be used as a decorative wall hanging, as a parokhet for an ark, or to make a cloth purse or tent. It may also be used for burial shrouds, since the deceased are exempt from mitzvot. Likewise, one may manufacture sha’atnez garments for non-Jews, provided there is no concern that they will come into the possession of a Jew who might mistakenly wear them.

02. The Prohibition of Wearing and Draping

Clothing is intended to protect the body from cold, heat, and rain, and to provide adornment, dignity, and modesty. One who wears a sha’atnez garment for any of these purposes violates the prohibition, as the Torah states: “You shall not wear sha’atnez” (Devarim 22:11). The prohibition applies to shirts, pants, dresses, skirts, undergarments, socks, hats, cloth shoes, gloves, ties, decorative ribbons, and all other garments ordinarily worn. Even if only the garment’s hanging loop or attached label is sha’atnez, the garment may not be worn (SA YD 301:15).

The prohibition also applies when sha’atnez fabric is draped over the body for warmth, protection from heat, or modesty, even though it is not worn in the usual manner of a garment. The Torah states: “A garment of mixed kinds, sha’atnez, shall not come upon you” (Vayikra 19:19). Thus, any use of sha’atnez that provides a benefit ordinarily associated with clothing is prohibited. One may not cover oneself with a sha’atnez blanket or dry oneself with a sha’atnez towel, since both provide warmth. The Sages also prohibited using sha’atnez as a tablecloth, out of concern that someone might occasionally pull it over their legs for warmth (SA YD 301:9). For the same reason, they prohibited hanging a sha’atnez curtain, since adults or children might use it for warmth. It may, however, be hung above head height or made of stiff fabric, since it cannot then be used for warmth (ibid. 11). Nor may one use sha’atnez fabric to handle a hot pot or frozen object, since it protects the hand from heat or cold and thus provides a benefit ordinarily associated with clothing (ibid. 12).

One may, however, benefit from sha’atnez fabric in ways unrelated to clothing. Thus, it may be used for a tent or umbrella.

Moreover, according to many authorities, one may wear a sha’atnez garment when doing so serves a purpose entirely unrelated to clothing. Thus, if customs duty is imposed only on garments packed in luggage, a Jew transporting sha’atnez garments belonging to non-Jews may wear them over his clothes while crossing the border, provided he does not intend to benefit from them as clothing. Likewise, a clothing seller may put on a garment solely to display it to customers, provided he does not intend to derive any benefit from wearing it (Rosh; Ramban; Ran; Rema YD 301:6; Yam Shel Shlomo). Other authorities are stringent and prohibit wearing sha’atnez even for these purposes, whether to avoid customs duty or to display a garment to customers (Rambam, as understood by Beit Yosef; SA YD 301:5–6).^[1]

03. Sitting or Lying on Sha’atnez

By Torah law, one may sit or lie on sha’atnez fabric, even though it provides warmth. The Torah prohibition applies only when the sha’atnez is above or alongside the body in the manner of clothing, not when it is beneath the body, as the verse states: “A garment of mixed kinds, sha’atnez, shall not come upon you” (Vayikra 19:19). The Sages, however, prohibited sitting or lying on sha’atnez fabric, lest a loose thread wind around one’s skin or one mistakenly use the fabric as a covering. To prevent such errors, they extended the prohibition even when the sha’atnez is covered by ten layers of permitted fabric (Beitza 14b; SA YD 301:1).

If the sha’atnez fabric is too stiff to be used as clothing and lies on a firm floor or chair into which the person does not sink, however, the Sages did not prohibit sitting or lying on it. A layer must separate the fabric from the body, so that any loose thread cannot wind around the skin (SA YD 301:1). One may therefore lie on a stiff sha’atnez rug when another fabric is spread over it, or sit on a chair upholstered with sha’atnez when pants or a dress separate the body from the chair. Even if the upholstery itself is soft, it is treated as stiff fabric as long as it is stretched taut over the chair with nails or glue (Panim Me’irot 2:113).^[2]

04. What Is Sha’atnez?

To make a garment of wool or linen, the raw materials must undergo three stages alluded to in the word sha’atnez, as the Mishna explains: “Sha’atnez: something that is shua, tavui, and nuz” (Mishna, Kilayim 9:8). First, shua: smoothing the wool or flax by combing. Second, tavui: spinning the fibers into thread. Third, nuz: intertwining, whether by weaving wool and linen threads together as warp and weft to form cloth, or by joining linen thread to a wool garment through tying or sewing.

In practice, wool and linen form prohibited sha’atnez in four principal ways: when raw wool and flax fibers are blended, combed, spun together into thread, and woven into cloth; when wool and linen threads are produced separately and then woven into a single fabric, such as linen warp and wool weft; when wool fabric is sewn or tied with linen thread, or linen fabric with wool thread; and when wool and linen fabrics are sewn together.

What these cases have in common is that the wool and linen underwent all three stages of shua, tavui, and nuz. If they did not undergo all three stages, however, as with felt made by compressing raw wool or flax without spinning or weaving, the overwhelming majority of Rishonim maintain that joining them is not prohibited by Torah law. Rambam disagrees and maintains that even wool and flax that underwent only the first stage of smoothing and combing before being made into felt are prohibited by Torah law when joined.^[3]

05. Threads Composed of Two Species

When a thread is made from sheep’s wool together with another material, such as cotton, its status follows the majority. If it is mostly cotton, the small amount of wool is disregarded, and the thread is considered cotton and may be joined to linen. Likewise, a thread made from hemp and flax may be joined to wool if it is mostly hemp. This principle applies even when raw wool and raw flax have already been mixed together: another material, such as cotton, may be added until it exceeds either the wool or the flax, thereby nullifying that component, and threads made from the resulting mixture are permitted. If the third material does not exceed either the wool or the flax, however, a garment woven from the resulting threads is prohibited by Torah law (Yerushalmi, Kilayim 9:1; SA YD 299:1).

Raw wool and flax can be nullified in a majority, but once they have been spun into thread, they acquire significance and are not nullified even in a thousand times their volume. Thus, a cotton garment sewn with a plied wool-and-linen thread is prohibited by Torah law even if the cotton is a thousand times greater. Likewise, a single wool thread mixed into a large linen garment – or a linen thread into a wool garment – renders the entire garment prohibited. Even if the thread can no longer be located, the garment remains prohibited until it is removed (SA and Rema YD 299:1).^[4]

06. Joining Wool and Linen; Wearing Them Together

Whenever wool and linen are joined directly and securely, the garment is prohibited by Torah law as sha’atnez. Thus, a skirt in which wool and linen fabrics are sewn together, or a wool coat with a linen hanging loop or linen loops, is prohibited by Torah law.

If the wool and linen are not joined to one another, however, most authorities permit the garment. Thus, if wool fabric is sewn to one side of a cotton garment and linen fabric to the other, there is no prohibition, since the wool and linen are not connected. The same applies when pieces of wool and linen are placed inside a lining without being joined to one another (R. Shimshon of Sens; Ramban; Rosh; Rashba). Rambam, by contrast, maintains that once both materials are attached to a single garment, the entire garment is prohibited by Torah law. In practice, the accepted custom follows the lenient view, although the scrupulous are stringent (Rema YD 300:5).^[5]

Sha’atnez is prohibited only when wool and linen are joined. When they remain separate, they may be worn together. One may therefore wear a wool shirt over a linen shirt and fasten a belt around both, wear a wool belt with linen pants, or fasten a wool garment to a linen garment with buttons that open easily or with Velcro. In each case, the garments are held together only temporarily and are not permanently joined (SA and Rema YD 300:3–4).^[6]

Some maintain that one should not wear wool socks over linen socks, since the linen socks cannot be removed without first removing the wool socks and the two are therefore considered firmly joined (Rema YD 300:4). Most authorities permit this, however, because there is no permanent attachment. This is the accepted practice (SA YD 300:4; Levush; Shakh YD 300:8; AHS YD 300:24).

07. Wool and Linen Garments, Past and Present

In the past, most garments were made of wool or linen. Wool is an excellent insulator and keeps the body warm in winter. It also absorbs relatively little dirt, and rain tends to run off it; these qualities made it the standard material for coats. Wool takes dye readily and retains its color, and because it tends to return to its original shape, wrinkles often smooth out on their own. For these reasons, wool garments remain looking new for a relatively long time.

Linen was considered a comfortable, high-quality fabric. Flax fibers are strong, and when spun into fine threads, they can be woven into especially attractive white garments. The natural variations in the thread’s thickness also give linen a distinctive appearance. Linen was so prized that the Sages taught that men in Eretz Yisrael should bring joy to their wives on the festival by giving them pressed linen garments, which women especially appreciated (Pesaḥim 109a). Linen is light and does not insulate, making it well suited to summer clothing through which air can circulate and cool the wearer. Its disadvantages are that it wrinkles easily, absorbs dirt, and is relatively difficult to clean. Once a suitable substitute became available, linen’s status declined sharply.

Cotton, whose production became widespread several centuries ago, is linen’s natural substitute. Although cotton is slightly warmer, it offers several advantages: it is easier to grow and spin, and cotton garments wrinkle less and are easier to wash. Today, the world produces approximately 80 times as much cotton as flax, while most flax is used to make strong thread and for other non-clothing purposes. Because cotton can also be woven into thick winter garments, it has largely replaced wool as well; global cotton production is now approximately 25 times that of wool. Other plant- and animal-based fibers have further reduced wool and linen’s share of the clothing industry.

About three generations ago, manufacturers learned to produce synthetic materials from petroleum byproducts, including plastic, nylon, and synthetic fibers such as polyester and acrylic, from which fabrics can be made. Early synthetic garments were neither breathable nor insulating, causing wearers to suffer from both perspiration and cold; only their low cost allowed them to compete with natural fabrics. As the technology improved, synthetic fabrics became more breathable and insulating. Because they are also less expensive and easier to clean and iron, they became extremely common. By 2018, manufactured fibers accounted for more than 70 percent of global fiber production, up from 60 percent a decade earlier. Wool and linen together accounted for only about 1 percent of the clothing industry, and their share appeared likely to continue declining^[7]

In practice, little linen clothing remains apart from a small number of luxury shirts and suits. Because linen thread and fabric are strong, however, they are sometimes used to reinforce parts of coats and suits, such as collars and the areas where buttons and buttonholes are sewn.

Wool garments have also become less common for the reasons discussed above. Nevertheless, wool’s warmth and resistance to rain and dirt make wool sweaters attractive to those who prefer a natural, breathable material, while its prestigious appearance and durability lead many to choose wool suits and coats.