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]
[10]. As we learned in note 1, authorities disagree about when one is liable for lashes for sowing vineyard kilayim in Eretz Yisrael. Rambam rules in accordance with R. Yoshiya: one is liable twice only if he sows a grape seed together with two seed species be-mapolat yad, in a single act of sowing. Regarding the Diaspora, the Sages said that practice follows R. Yoshiya’s view (Berakhot 22a; Kiddushin 39a).
According to Rambam (MT, Laws of Kilayim 8:13–14), there is no prohibition against sowing grain or vegetables in a vineyard in the Diaspora, but the produce that grows there is nevertheless forbidden for benefit. His reasoning is that since such produce is forbidden for benefit by Torah law in Eretz Yisrael, the Sages decreed that it is forbidden for benefit in the Diaspora as well. Rosh, Raavad, and Terumat ha-Deshen §194 disagree. In their view, whatever may be sown in a vineyard in the Diaspora may also be used if it grows there. Rema YD 296:69 rules this way. Since the dispute concerns rabbinic law, the halakha follows the lenient authorities.
According to Rosh, even Rambam agrees in principle. Rambam prohibited the produce only when one bought a vineyard that already contained vegetables, out of concern that they may have been sown be-mapolat yad.
[11]. The authorities permitted buying grapes and cucumbers from non-Jews despite the concern that they had been grown as prohibited kilayim, because most grapes and cucumbers are not grown that way. Since the doubt arose only after the produce had already left the non-Jew’s field, the rule of kol de-parish me-ruba parish applies: anything separated from a group is presumed to have come from the majority.
The authorities also allowed the produce on the basis of a safek sfeika, a double doubt. First, perhaps these grapes or vegetables were not grown in violation of kilayim at all. Second, even if they were grown near a vineyard, perhaps the halakha follows R. Yoshiya as understood by Rabbeinu Tam and Ri, discussed above in note 1. According to that view, unless the seeds were sown be-mapolat yad, there is no prohibition against eating the produce. Additional doubts were combined as well (Mabit 3:127; Maharitatz, Ḥadashot §31; Maharshdam; Keneset ha-Gedola; Birkei Yosef YD 296:1).
It seems to me that these leniencies may have applied specifically when the markets served primarily non-Jewish buyers, who formed the majority. Today, however, if it is known that non-Jews grow kilayim for sale in markets intended primarily for Jewish buyers, the kilayim may have the status of kavu’a – a fixed source – which is not nullified by the majority. When the prohibited produce became mixed in only incidentally, there is room to be lenient. But if kilayim produce is sold regularly in specific places, one may not buy produce there as long as there is doubt whether it is kilayim. Certainly, kashrut agencies that seek a higher standard must be careful about this.
