By Torah law, terumot and ma’asrot apply only to produce grown in the ground. Produce grown in a perforated pot is also considered ground-grown. Produce grown in an unperforated pot, or on growing surfaces that separate it from the ground, is exempt by Torah law. The Sages, however, required separation from such produce with a berakha (Yoma 83b).
Produce grown inside a house is exempt from terumot and ma’asrot, even if it is planted directly in the ground beneath the house, according to Raavad. Rambam agrees that it is exempt by Torah law, but maintains that the Sages required separation rabbinically. Therefore, one separates terumot and ma’asrot from indoor produce without a berakha (MT, Laws of Ma’aser 1:10).
One must separate terumot and ma’asrot from produce grown in greenhouses with a berakha, and one gives ma’aser rishon to a levi and ma’aser ani to a poor person.[17]
[17]. The Yerushalmi states that a tree grown inside a house is exempt from terumot and ma’asrot even if it is planted directly in the ground beneath the house, because the Torah obligation applies only to produce that grows “in the field”: “You shall surely tithe all the produce of your seed that comes forth from the field year by year” (Devarim 14:22; Yerushalmi, Orlah 1:2). Regarding shevi’it, however, the Yerushalmi leaves the question unresolved.
Rambam limits the Yerushalmi’s exemption to the Torah obligation. By Torah law, indoor produce is exempt, but the Sages required separation rabbinically (MT, Laws of Ma’aser 1:10). Raavad maintains that indoor produce is exempt even rabbinically. Therefore, in practice, one separates terumot and ma’asrot from indoor produce without a berakha.
The discussion above concerns produce grown inside an ordinary house. Greenhouses must be assessed independently. According to Rambam, who requires separation even from indoor produce, greenhouse produce is certainly subject to terumot and ma’asrot with a berakha. Some maintain that, according to Raavad, greenhouse produce should be treated like indoor produce and separated without a berakha. It seems clear, however, that even Raavad would agree that terumot and ma’asrot apply to greenhouse produce. His exemption for indoor produce is based on the fact that people do not normally grow crops inside a house. A greenhouse, by contrast, is built for cultivation. Therefore, produce grown in a greenhouse is subject to terumot and ma’asrot with a berakha, and one gives ma’aser rishon to a levi and ma’aser ani to a poor person.
Hydroponic produce raises a separate question because it grows without soil. Some maintain that terumot and ma’asrot nevertheless apply to it, as they apply to produce grown in a field (Har Tzvi, Zera’im 2:31). Others maintain that without soil, the obligation does not apply (Neḥpeh Ba-kesef 1, YD 5; Sefer ha-Shemita 2, 8:2, p. 97). In practice, because of the uncertainty, one separates terumot and ma’asrot from hydroponic produce without a berakha. This is also the ruling of Mishpetei Eretz 1:19 and Kedushat ha-Aretz 1:53.
Regarding shevi’it, I wrote in Peninei Halakha: Shevi’it 2, note 13, that since shevi’it today is rabbinic, one may grow vegetables inside a house (Pe’at ha-Shulḥan 20:52). Aḥaronim disagree about greenhouses. Some maintain that a greenhouse has the status of a house; since shevi’it today is rabbinic, they permit growing vegetables in a greenhouse during the seventh year (Yabi’a Omer 9, YD 31; Minḥat Shlomo 3:158:7). Others maintain that since vegetables are commonly grown in greenhouses, a greenhouse has the status of a field. According to this view, agricultural work is forbidden there during shevi’it (R. Yosef Shalom Elyashiv), and greenhouse produce is subject to terumot and ma’asrot with a berakha (R. Nissim Karelitz). This appears to be the correct view: a greenhouse has the status of a field.
Nevertheless, regarding shevi’it, I wrote that if the vegetables are grown in an unperforated pot inside a greenhouse, those who wish to be lenient may do so, since the case involves uncertainty on two rabbinic levels. This leniency should not be extended to terumot and ma’asrot. Although the Yerushalmi is more explicit about exempting indoor produce from terumot and ma’asrot than from shevi’it, that local comparison does not determine the practical ruling today. In our time, the obligation of shevi’it is weaker overall than the obligation of terumot and ma’asrot.
Several considerations explain this distinction. Regarding terumot and ma’asrot, some maintain that the obligation applies today by Torah law even without a Jewish majority in the Land (Rashi; Raavad). Others maintain that the obligation returns to Torah status when Jewish sovereignty over Eretz Yisrael is restored, a principle with renewed practical significance after the establishment of the State of Israel (Rashba and those who follow him; see below, 12:17 note 18). According to the remaining authorities, terumot and ma’asrot remain a full rabbinic obligation (see below, 12:11).
Shevi’it, by contrast, stands on weaker footing today. According to most authorities, its present-day obligation is rabbinic, and some Rishonim maintain that today it is only a pious practice. Its obligation is weakened further by uncertainty about the shemita-year count, which affects shevi’it more than it affects terumot and ma’asrot (Peninei Halakha: Shevi’it 5:6–7). Moreover, even according to Rambam’s central view that both obligations today are rabbinic, shevi’it is further removed from its Torah-law form. Terumot and ma’asrot are rabbinic only because most of the Jewish people do not live in the Land. Shevi’it, however, is rabbinic because the majority of each tribe does not live in its ancestral portion (ibid. 5:3).
