kelayim – RabbiKaganoff.com

May a Non-Jew Own a Nectarine Tree?

For that matter, may a Jew?

I once received the following query:

“I am not Jewish, but I observe the laws of Noahides as recorded in the writings of Maimonides, which I have read in the Yale University translation. I am aware that a gentile may not graft one species of tree onto another. Does owning a nectarine tree violate this prohibition? I would be greatly appreciative if you could answer this question, since I have just purchased a house with a nectarine tree in the yard.

Sincerely,

Jacqueline Baker

250 Washington Blvd.

Asheville, NC” (name and address have been changed)

Many of us reading the title of this article may have wondered, “If I am permitted to eat nectarines, why shouldn’t I own a nectarine tree?” Although the answer to this question is fairly straightforward, there are many other issues that need clarification, before we can answer Jacqueline’s shaylah.

First, let us explain the halachos of tree-grafting applicable to Jews. Sadly, because many Jews are unfamiliar with these halachos and unaware of the prevalence of grafted trees, they often, unwittingly, violate these laws.

Also, most people misunderstand the prohibition against kelayim, which is often translated as “mixed species.” People often understand this to mean a prohibition against hybridization or cross-breeding. Although it is true that the Torah prohibits crossbreeding different species of animal, virtually all other types of forbidden mixtures have nothing at all to do with hybridization. We list here the six types of prohibited mixtures, called kelayim.

1. Wearing shatnez, which is a mix of wool and linen.

2. Cross-breeding two animal species.

3. Using two animal species to haul or work together. This mitzvah is usually called lo sacharosh, do not plow with an ox and a donkey together.

4. Grafting different tree species. A sub-category of this prohibition is planting one species on top of or inside another species, a process that is virtually non-existent in contemporary agricultural practice.

5. Planting other crop species in a vineyard. For this purpose, “crop” refers to an annual (grows for only one year and then dies) edible plant. Examples are: seeds that are eaten, like beans, wheat, and sesame; root vegetables, like radish; leaves, such as lettuce; or fruit, such as tomatoes or melons.

6. Planting two crop species together or near one another. This prohibition applies only to species that are eaten.

Although we usually assume that the word kelayim means “mixture,” some commentaries explain that this word originates from the same Hebrew root as the word “prison,” beis ke’le. Thus, Rav Hirsch (Vayikra 19:19) explains that the root word כלא means to keep or hold something back, and that the plural form kelayim is similar to yadayim or raglayim and means a pair. Therefore, the word kelayim means to pair together two items that should be kept apart.

In order to explain the prohibition against grafting trees, the subject of our article, I will first provide some scientific background for city dwellers like myself, who know almost nothing about gardening and horticulture. Having been a city slicker almost my whole life, I freely admit that I knew little about this subject until I did some research in order to understand the halacha.

Hybridization (cross-breeding) of plants occurs when one pollinates the flower of one species with pollen from a different species. However, most of the prohibitions of kelayim have nothing to do with cross-breeding species. In the case of “herbaceous plants,” that is, plants other than perennial (live for many years) trees and shrubs, kelayim is a prohibition against planting two crop species close together. Halacha prohibits planting a crop species inside a vineyard, planting one species too close to another already planted species (distances vary according to how many plants are growing together), planting one species on top of or inside another species, and sowing the seeds of two species together. Incidentally, these prohibitions apply only in Eretz Yisrael, with the exception of planting a crop species in a vineyard (Kiddushin 39a) and, possibly, of planting one species inside another (see Gemara and Tosafos, Chullin 60a; Rambam, Hilchos Kelayim 1:5 and Radbaz). Thus, someone in chutz la’aretz may plant his backyard garden with a wide variety of vegetables and other edibles without any halachic concern, whereas in Eretz Yisrael, someone planting a garden patch must be very careful to keep the different species separate. The complicated question of how far apart to plant them, and what qualifies as a valid separation if one plants them close together, is beyond the scope of this article (see Chazon Ish, Hilchos Kelayim 6:1).

(By the way, the halachic definition of a species often differs from scientific definition. For example, although some scientists consider wolves and dogs to be the same species, halacha does not; therefore, one may not crossbreed them or use them to haul a load together [Mishnah, Kelayim 1:6]. On the other hand, the Chazon Ish [3:7] discusses whether all citrus fruits are the same species regarding the laws of kelayim, which would permit grafting a grapefruit branch onto a lemon rootstock, whereas scientists consider them to be two distinct species.)

HARKAVAS ILAN – CROSS-GRAFTING

The laws of kelayim also prohibit grafting a branch of one species of tree onto the root stock, or lower trunk, of another species. Although a town dweller may feel that this is a rare occurrence, in fact, contemporary plant nurseries and tree farmers usually graft branches of a species that produces delicious fruit onto the hardier stock of a different species.

For example, most modern peach and nectarine trees are produced by grafting a peach or nectarine branch onto the stock of a hardier, botanically-related tree, such as an almond. As I will explain, someone who performs this, either in Eretz Yisrael or in chutz la’aretz, violates a Torah prohibition. According to many authorities, a non-Jew is also commanded regarding this mitzvah. This latter opinion contends that a Jew who causes a non-Jew to graft such a tree, or even to prune or water it after grafting was done, contravenes lifnei iveir, causing someone else to violate a prohibition.

Because so many trees are grafted nowadays, someone who owns a peach tree should have a horticultural expert check whether its rootstock is also a peach tree, or whether it is of a different species. If the stock is peach, even of a different variety, he may keep the tree; if the stock is of a different species, he should chop off the tree below the point of the graft. (Nobody has suggested that George Washington chopped down his father’s cherry tree because it was grafted onto a different species. Since George always strove for truth, however, this was, nonetheless, an additional good deed, at least according to some opinions.) As we will see shortly, there is no violation of bal tashchis in cutting down a grafted tree.

Often, even a non-expert can detect if a tree was grafted onto a different species by simply scrutinizing the tree. If the bark somewhere near the bottom of the tree looks very different from the upper part of the tree, this indicates that the upper part of the tree was grafted, possibly onto a different species. Before purchasing a new tree at a nursery, examine the trunk carefully for signs of grafting. If, indeed, this tree is the product of a graft onto a different species, then watering or pruning it violates a Torah law, as I will explain. Furthermore, one may not use a sprinkler to irrigate the rest of the lawn on which the tree stands, if this tree will benefit.

NECTARINE TREES

Nectarine trees are susceptible to a host of plant diseases, and, as a result, are usually grafted onto the stock of peach, plum, almond or other trees. It is unclear whether peach and nectarine are halachically considered the same species, but the other species are not the same, according to halacha. Therefore, watering a nectarine tree grafted onto a different species stock probably violates halacha.

By the way, according to halacha, one may plant or maintain different species of trees in close proximity, presumably because grown trees do not look mixed together but stand distinct.

DOES THE PROHIBITION AGAINST GRAFTING APPLY IN CHUTZ LA’ARETZ?

Although most agricultural mitzvos (mitzvos hateluyos ba’aretz), such as terumah, maaser, and shmittah apply only in Eretz Yisrael, some of these mitzvos apply also in chutz la’aretz, such as the mitzvah of orlah, which prohibits using fruit that grows on a tree before it is three years old.

Although the laws of orlah differ when the tree grows in chutz la’aretz, the fruit produced before the tree is three years old is nevertheless prohibited.

Where does kelayim fit into this picture? Of course, some kelayim prohibitions, such as shatnez, cross-breeding animals and lo sacharosh are not agricultural and, therefore, apply equally in Eretz Yisrael and in chutz la’aretz. Among the agricultural prohibitions of kelayim, some apply in chutz la’aretz also, whereas others apply only in Eretz Yisrael.

Planting vegetables and other edible crops together applies only in Eretz Yisrael, grafting trees applies equally in chutz la’aretz and in Eretz Yisrael min hatorah, while planting in a vineyard applies in chutz la’aretz, but only miderabbanan (Kiddushin 39a).

MAY I OWN KELAYIM?

The Gemara (Moed Katan 2b) cites a dispute whether maintaining kelayim in a vineyard (in Eretz Yisrael) is prohibited min hatorah. Rabbi Akiva contends that building a fence to assist the growth of the two different species together violates a Torah law, whereas the Sages contend that it does not (Rashi to Avodah Zarah 64a).

Most poskim conclude that one may not own kelayim in a vineyard, but must remove the plant that is causing kelayim (Shulchan Aruch Yoreh Deah 297:2). The Rambam (Hilchos Kelayim 1:2) paskins that owning kelayim is prohibited only miderabbanan, whereas the Rosh (Hilchos Kelayim #3) prohibits this min hatorah. (We should note that Shu’t Chasam Sofer [Yoreh Deah #282] contends that Tosafos [to Avodah Zarah 64a s.v. Rabbi Akiva] permits owning kelayim.)

WHAT ABOUT OWNING A GRAFTED TREE?

Most poskim assume that one may not own a kelayim tree, just as one may not own kelayim in a vineyard. Furthermore, they contend that this halacha applies, whether the tree is in Eretz Yisrael or in chutz la’aretz (Rosh, Hilchos Kelayim Chapters 1& 3; Pischei Teshuvah, Yoreh Deah 295:2, quoting many poskim).

However, in times past, many observant Jews purchased agricultural properties that contained kelayim trees, and they did not cut down those trees. Was there any justification for their actions? Many halachic responsa discuss what was, apparently, a widespread practice in the eighteenth and nineteenth centuries. Whereas most poskim rule that these Jews violated the halacha, some authorities justify the practice of owning grafted trees, at least in chutz la’aretz (Shu’t Chasam Sofer, Yoreh Deah #288; cf. Aruch Hashulchan, Yoreh Deah 295:17-18). Even these opinions agree that it is preferred to follow the stricter approach and cut down the grafted part of the tree.

I THOUGHT THAT ONE MAY NOT CUT DOWN A FRUIT-BEARING TREE?

Although it is usually prohibited to chop down a tree that bears enough fruit to be profitable, this prohibition does not exist when owning the tree involves a prohibition. Furthermore, bal tashchis, generally, does not exist when one is trying to enhance one’s observance of mitzvos.

Nevertheless, it is preferred to have a non-Jew chop down the tree, since he has no mitzvah of bal tashchis.

DOES THE MITZVAH OF KELAYIM APPLY TO NON-JEWS?

In general, a non-Jew is required to observe only seven mitzvos. However, there are many opinions that require non-Jews to observe certain other mitzvos. The Gemara (Sanhedrin 56b) quotes a dispute concerning whether a non-Jew must observe certain of the kelayim mitzvos. According to the Sages, no aspect of the prohibition of kelayim applies to bnei Noach, whereas Rabbi Elazar contends that they are included in some of the kelayim prohibitions, but not others. Specifically, they are prohibited from mating different animal species and from grafting one species of fruit tree onto another, but they may plant different species together or in a vineyard, and they may wear shatnez.

Why are they included in some prohibitions but not others?

Describing the creation of plants, the Torah says: “And G-d said, ‘The earth shall sprout forth vegetation, herbage that produces seed; edible trees that produce fruit of their own species…’ And the earth produced vegetation, herbage that produces seed of its own species and trees that bear seed-bearing fruit of their own species” (Bereishis 1:11-12).

Reading the pasuk carefully, we see that Hashem ordered only the trees, and not the herbaceous plants, to “produce fruit of their own species.”

Even though the herbage did, in the end, produce “seed of its own species,” this was not because it was commanded. The Gemara derives from other sources that, just as the earth was commanded to keep tree species distinct, so, too, Adam harishon and all his descendants were commanded to keep these species distinct. But since the herbaceous world was never commanded to keep its species distinct, Adam was not commanded concerning this halacha. Therefore, although Jews may not plant different species together, bnei Noach may (Yerushalmi Kelayim 1:7, quoted by Gra, Yoreh Deah 295:2).

WHICH OPINION DO WE FOLLOW?

Do we rule like the Sages that a non-Jew is not included in the prohibition of harkavas ilan, or like Rabbi Elazar, that he is? The Rambam (Hilchos Melachim 10:6) rules like Rabbi Elazar, that a non-Jew may not graft one species of tree onto another, whereas the Ritva (Kiddushin 39a s.v. amar Rabbi Yochanan) and the Shach (Yoreh Deah 297:3) are lenient.

Although we usually follow the Rambam’s opinion, some poskim suggest that we might be able to rule leniently, if only a rabbinic prohibition is involved, such as where the grafted tree exists already and one is not watering or pruning it (Chazon Ish, Kelayim 1:1).

MS. BAKER’S SHAYLAH

I mentioned earlier that a Jew who prunes or waters a kelayim tree violates the Torah prohibition, whether in Eretz Yisrael or in chutz la’aretz. According to most authorities, one may not even own this tree, and one is required to cut down the grafted part. However, since this last prohibition is only miderabbanan, according to most poskim, non-Jews may allow a grafted tree to survive and may even build a fence around it, since they are not required to observe rabbinic prohibitions. (Compare, however, Shu’t Mahari Asad, Yoreh Deah #350 and Shu’t Maharsham 1:179.) Ms. Baker may not water or prune a grafted tree, because that is halachically equivalent to planting it, which is prohibited according to most opinions. In my opinion, she may also not operate her sprinkler system to irrigate her lawn, if the kelayim tree will benefit as a result.

May Ms. Baker ask another non-Jew to water her tree? The poskim dispute whether a non-Jew may ask or hire someone else to violate a mitzvah. Most contend that this is permissible, because the mitzvah of lifnei iveir, causing someone else to violate a mitzvah, does not apply to non-Jews (Tosafos, Avodah Zarah 16b s.v. lenachri). Other authorities (Ginas Veradim, Klal 43) prohibit this, basing themselves on earlier sources that prohibit a ben Noach from violating a transgression that logic tells us to avoid (Rabbeinu Nissim, Introduction to Shas).

MAY WE EAT THE FRUITS OF A GRAFTED TREE?

One may eat the fruits of a grafted tree (Rambam, Hilchos Kelayim 1:7, based on Yerushalmi). One may even take the shoot of a grafted tree and plant it, after it has been severed from the original tree.

SEPARATION OF SPECIES

In all six types of kelayim mentioned above, the general criterion is to avoid the appearance of different species being intermingled.

Concerning this, Rav Hirsch (Vayikra 19:19) writes, “The Great Lawgiver of the world separates the countless numbers of His creations in all their manifold diversity, and assigns to each one of them a separate purpose and a separate form for its purpose.”

In addition, observing the laws of kelayim helps us remember how various species obeyed Hashem’s instructions to remain separate during their creation (the source for some halachos of kelayim, as we saw above). This reminds the contemplative Jew that if the plants heeded Hashem’s word during the Creation, how much more are we obligated to obey all His instructions.

The author thanks Dr. Joshua Klein of the Volcani Institute and Rabbi Shmuel Silinsky for their tremendous assistance in providing horticultural information for this article.

Desktop Gardening, Or Growing Vegetables in Thin Air

Well, not quite thin air, because plants, like the rest of us, require nutrients and water to grow. Although the word “aeroponics” does not show up in either of the dictionaries I use for handy reference, and is totally ignored by my spellchecker, it is actually common enough that it should be appearing in any current dictionary of the English language. I admit that I had no idea what the word meant when Yehudah asked me the following shaylah:

“To overcome the many problems that may be involved in purchasing products during shemittah, we want to purchase a large aeroponics kit and grow our own vegetables. Will this present us with any halachic problems in terms of either the laws of shemittah, or the laws of kelayim?”

And so, I began my education about this subject. This is what I discovered:

Aeroponics is a method of growing vegetables or herbs without soil by spraying the plant roots with water and nutrients (as opposed to hydroponics where the roots are submerged in a nutrient solution). Although it can be done on a commercial scale, the company Yehudah contacted sells aeroponic kits for growing herbs and vegetables in the comfort of one’s home. Each kit includes the seeds and nutrients required for specific types of plants, a complete, self-contained, open-top growing tank that includes its own light fixtures and instructions on how to make it all work. Just add water and electricity to run the pump and lights.

The company advises growing lettuce, herbs, tomatoes, peppers, or strawberries each in its own tank, since they have quite different needs. Nevertheless, the first question we will discuss is whether this is a halachic requirement to do so because of the prohibition of kelayim.

WHAT IS KELAYIM?

It is important to clarify a common misconception. The prohibition of kelayim is not the creation of a new species; it is the appearance that one is mingling two species together. This is why hauling loads with two species of animal, grafting one tree species onto another, mixing wool and linen in a garment or planting grains in a vineyard are all Torah violations of kelayim, although none of these acts affect the genetic make-up of the species.

Yehudah’s question involves two halachic topics:

Kelayim

Could someone gardening on his desktop possibly violate the mitzvah of kilei zera’im, which prohibits planting two species together or near one another? Violating this prohibition requires three basic conditions, all of which Yehudah met:

The prohibition applies to herbaceous, as opposed to woody plants, meaning that it does not apply to trees and shrubs, but it does apply to vegetables and many herbs. Thus, one may plant seeds of different trees together, yet one is forbidden to plant a mix of vegetable seeds (Rambam, Hilchos Kelayim 1:6).
The prohibition of kilei zera’im applies only to edible crops (Rambam, Hilchos Kelayim 1:4). Thus, one may plant seeds of different ornamental flowers and grasses within close proximity.
It applies only in Eretz Yisroel (Kiddushin 39a), and is min hatorah according to most halachic authorities, even today (implied by Rambam, Hilchos Kelayim 1:1). (However, note that in Rashi’s opinion [Shabbos 84b, s. v. ve’achas] the prohibition of kilei zera’im in Eretz Yisroel is only miderabbanan and Tosafos [Yevamos 81a, s.v. mai] contends that although kilei zera’im is essentially min hatorah, in our era it is only rabbinic because most of the Jewish people do not currently live in Eretz Yisroel.) Therefore, someone in Chutz La’Aretz may plant his backyard garden with a wide variety of herbs and vegetables, without any concern for how close they are, whereas in Eretz Yisroel, someone planting a garden patch must be very careful to keep the different species separate (Rambam, Hilchos Kelayim 1:3). I will discuss later how far apart one must plant different species to avoid violating this prohibition (see Chazon Ish, Hilchos Kelayim 6:1).
Shemittah

One may not plant in Eretz Yisroel during shemittah. Does planting this indoor garden in Eretz Yisroel violate the laws of shemittah?

Yehuda’s question requires analyzing the following subjects:

Do these mitzvos apply when planting indoors?

Would they apply when planting outdoors in a pot or planter that is disconnected from the ground?

Do they apply when one is not planting in soil?

INDOORS

Two Talmudic passages discuss whether agricultural mitzvos apply indoors. In Eruvin (93a), the Gemara prohibits planting grain in a vineyard that is underneath a roof extending from a house. This passage implies that agricultural mitzvos apply within physical structures.

On the other hand, the Talmud Yerushalmi (Orlah 1:2) discusses whether three agricultural mitzvos, orlah (the prohibition to use fruit produced in the first three years of a tree’s life), maaser (tithing produce), and shemittah, apply to indoor plants. The Yerushalmi rules that whereas orlah applies, there is no requirement to separate maaser on produce grown indoors. The Yerushalmi questions whether shemittah applies to indoor produce, but does not conclude clearly whether it does or not.

WHY IS ORLAH DIFFERENT FROM MAASER?

The Yerushalmi notes that when the Torah instructs us to separate maaser, it states: You shall tithe all the produce of your planting, that which your field produces each year (Devarim 14:22). Since the Torah requires maaser only on produce of a field, there is no requirement to separate maaser from what grows indoors, since, by definition, a field is outdoors. Therefore, one need not separate maaser min hatorah when planting indoors, even if one is planting directly in the soil floor of the structure. (The Rishonim dispute whether there is a rabbinic requirement to separate terumos and maasros when planting in the ground within a building; see Rambam and Raavad, Hilchos Maasros 1:10.)

However, when the Torah describes the mitzvah of orlah, it introduces the subject by stating When you will enter the Land (Vayikra 19:23). A tree planted indoors is definitely in the Land of Israel, and thus is included within the parameters of this mitzvah, even if it is not in a field.

SHEMITTAH INDOORS

Do the laws of shemittah apply to produce grown indoors? Does shemittah apply only to a field, or to anything planted in the Land of Israel?

The Yerushalmi notes that when the Torah discusses the mitzvah of shemittah, it uses both terms, land (Vayikra 25:2) and field (Vayikra 25:4). It is unclear how the Yerushalmi concludes and the poskim dispute whether the mitzvah of shemittah applies indoors in Eretz Yisroel. Ridbaz (Hilchos Shevi’is, end of Chapter 1), Chazon Ish (Shevi’is 22), and Pnei Moshe all rule that it does; Pe’as Hashulchan (20:52) rules that it does not. Most later authorities conclude that one should not plant indoors during shemittah, at least not in the soil. I will discuss, shortly, whether one may plant during shemittah indoors hydroponically or in an indoor area where the dirt floor is covered.

INDOOR KELAYIM

May one plant different species next to one another indoors? Does the prohibition of kelayim apply to produce planted under a roof?

Based on the Talmud Yerushalmi we quoted above, we should be able to establish the following rule:

When the Torah commands that a specific mitzvah applies to the land, it is immaterial whether the planting is indoors or outdoors. However, when the Torah commands that a mitzvah applies to a field, it does not apply indoors. As noted above, an indoor area can never be called a field.

How does the Torah describe the mitzvah of kilei zera’im? The Torah states “you shall not plant kelayim in your field” (Vayikra 19:19), implying that the mitzvah does not apply indoors. Thus, we should conclude that there should be no prohibition min hatorah against planting herbs or vegetables proximately if they are indoors. (Nevertheless, both the Yeshuos Malko [Hilchos Kelayim 1:1] and the Chazon Ish rule that kilei zera’im does apply indoors and apparently disagree with the above analysis. I will take this into consideration later.) However, it is probably prohibited miderabbanan, according to the opinion that the Sages required tithing produce grown indoors.

BUT…

At this point, the discerning reader will note a seeming discrepancy with the passage from Eruvin 93a that I cited earlier. The Gemara rules that one may not plant grain in a roofed vineyard, implying that kelayim does apply indoors. This seemingly conflicts with my conclusion based on the Yerushalmi that one may plant different herbs or vegetables proximately indoors, without violating the prohibition of kelayim.

THE SOLUTION: GRAPES VERSUS VEGETABLES

The answer is that there is a major halachic difference between the two cases: Planting grain in a roofed vineyard violates kilei hakerem, planting other crops in a vineyard. Although both kilei hakerem and kilei zera’im are called kelayim, kilei hakerem is a separate mitzvah and is derived from a different pasuk than the one prohibiting kilei zera’im, planting herbaceous species together. The Torah commands us about kilei hakerem by stating: “You shall not plant your vineyard with kelayim (Devorim 22:9), using the word vineyard, not field. Whereas a field cannot be indoors, a vineyard could.

At this point, we have resolved the first of our questions asked above:

“Do these mitzvos apply when planting in a covered area?”

The answer is that planting kelayim species should seemingly not apply, although some prominent authorities disagree. Shemittah does apply, according to most poskim.

FLOWERPOTS

We now progress to our next question:

Do agricultural mitzvos apply to plants growing in Eretz Yisroel in closed pots and planters that are separated from the ground and yet exposed to the elements?

The Mishnah (Shabbos 95a) teaches that someone who plants in a flowerpot that has a hole in its bottom, called an atzitz nakuv, violates Shabbos as if he planted in the earth itself. However, planting in a flowerpot that is fully closed underneath, called an atzitz she’aino nakuv, is forbidden only because of rabbinic injunction and does not involve a Torah-prohibited violation of Shabbos. The same categories usually apply to agricultural mitzvos: plants in a pot with a hole in the bottom are equivalent to being in the ground itself; those whose bottom is completely sealed are included in agricultural mitzvos by rabbinic injunction.

Therefore, one must separate terumah and maaser from produce grown in pots or planters, whether or not the containers are completely closed underneath, and one would violate kelayim if one planted two species near one another in a flowerpot or other container.

There are some exceptions to this rule. In some instances, planting in a closed container is the same as planting in the ground. According to the Rambam [Hilchos Maaser Sheni 10:8] and the Shulchan Aruch [Yoreh Deah 294:26], orlah applies min hatorah to a tree planted in a closed flowerpot. The reason for this phenomenon is that a tree root will, with time, perforate the bottom of its pot, and therefore, it is already considered to have a hole and be part of the ground below.

SHEMITTAH IN A HOTHOUSE

On the other hand, there are also poskim who contend that shemittah does not apply at all, even miderabbanan, to items planted in a planter or flowerpot whose bottom is completely closed. What is the halacha if one plants in a covered area in a pot that is completely closed underneath? May one be lenient, since the pot is both indoors and is also an atzitz she’aino nakuv, which is not considered connected to the earth min hatorah? This question leads us directly to the following question that Israeli farmers asked, about sixty years ago: May one plant in a hothouse during shemittah, in a closed-bottom vessel? As I mentioned above, although some authorities permit planting in the soil indoors during shemittah, the consensus is to be more stringent. However, many poskim permit planting in pots in a hothouse, if its floor is covered with a thick material, such as heavy plastic or metal (see Chazon Ish, Shevi’is 26:4; Mishpatei Aretz pg. 239; however, cf. Shu’t Shevet HaLevi who prohibits this).

AEROPONICS AND SHEMITTAH

At this point, we can discuss our original question: Aeroponics, like a hothouse, means growing indoors, and is also similar to planting atop a floor that is covered with metal or heavy plastic. Based on the above discussion, we may conclude that most authorities would permit planting aeroponically during shemittah, provided that the bottoms of the tanks are metal or plastic.

WHAT ABOUT KIL’EI ZERAIM?

We still need to explore whether desktop planting violates the laws of kilei zera’im.

I concluded above that there is probably only a rabbinic prohibition of kilei zera’im on indoor planting, but that some prominent authorities prohibit it min hatorah. Can we offer a solution for Yehudah’s plans? To answer this we need to address another issue.

KEEP YOUR DISTANCE

As I mentioned in the beginning of this article, kelayim occurs when different species are mingled together. If there is enough distance between the plants, no mingling is transpiring.

How far apart must I plant herbs or vegetables to avoid violating kelayim? This is a complicated topic, and its answer is contingent on such factors as how and what one is planting. I will, however, go directly to the conclusion that affects our case.

Since the desktop garden involves only herbs and vegetables and only a single plant or a few plants of each species, the halacha requires only a relatively small distance between species. Min hatorah one is required to plant only one tefach apart; the additional space requirement is rabbinic (see Rambam, Hilchos Kelayim 3:10). The poskim dispute how distant one is required to avoid a rabbinic prohibition. Some require that the plants are at least three tefachim apart [about ten inches] (Rashi, Shabbos 85a), whereas others determine that it is sufficient for the plants to be only 1½ tefachim apart [about five inches] (Rambam, Hil. Kelayim 4:9; Shulchan Aruch, Yoreh Deah 297:5). In the case of the aeroponically-grown produce, since the tanks are completely closed underneath, they have, at worst, the halachic status of atzitz she’eino nakuv, a closed pot or planter, considered part of the ground only because of rabbinic injunction, but not min hatorah. We can, therefore, conclude that as long as the seeds are placed more than a tefach apart, we avoid any Torah prohibition. As far as the possible rabbinic prohibition if the plants are only a bit more than one tefach apart, we could additionally rely on the likelihood that kilei zera’im does not apply indoors in an eino nakuv planter.

Having completed the halachic research, we corresponded with the company that produces the desktop planting kits, asking them how far apart are the holes in which one “plants” the seeds, and how many different herbs and vegetables can be planted in a single tank.

The company replied that the kit usually has seven holes, each four inches apart from the other, center to center. When planting peppers and tomatoes, which grow larger than the greens or herbs, the company recommends plugging four of the holes and using only three, which are far enough apart to avoid any kelayim issue, according to our conclusion. However, when planting herbs and greens, the distance between the holes is just about the distance that might present a halachic problem. I therefore advised Yehudah to plant in alternative holes, even when planting herbs of different varieties.