Question #1: Spelt

I understand that spelt is a type of wheat. May I plant a small patch of it next to my wheat field?

Question #2: Trees and Ornamentals

I purchased a property in Israel that has grapes and other trees and ornamentals growing on it. What do I do to avoid violating the prohibition of kil’ayim?

Question #3: Tomatoes

May I plant various types of tomatoes next to one another?

Foreword:

In parshas Ki Seitzei, the Torah teaches the mitzvah not to plant your vineyard with kil’ayim (Devarim 22:9), after which the Torah mentions two other kil’ayim prohibitions: doing work with different animal species together and wearing shatnez. In parshas Kedoshim, the Torah introduces several mitzvos called kil’ayim when it says, “You shall keep my laws. You shall not breed your animals as kil’ayim, you shall not plant your field as kil’ayim and you shall not wear kil’ayim shatnez garments” (Vayikra 19:19).

I have written many times about the prohibitions of wearing shatnez, grafting one tree min (species) onto another and crossbreeding animals, but I have never written an article devoted to this week’s topic — the kil’ayim prohibitions in a vineyard and in a field. Please note that this article is only a general introduction to these mitzvos and not halacha le’maaseh — the topics are far more complex than can be covered in one article. For this reason, the opening questions in this article are going to be left unanswered.

Kil’ei hakerem

Kil’ei hakerem is the prohibition of planting an herbaceous (meaning non-woody, i.e.  – a plant other than a trees or a shrub), cultivated plant in a vineyard or adjacent to a grapevine. This mitzvah applies min haTorah in Eretz Yisrael and as a rabbinic prohibition in chutz la’aretz (Orlah 3:9; Kiddushin 39a). It also includes planting above or below grapes, such as, if the vine is trained onto a trellis or other framework.

Kil’ei hakerem is the only instance in which the Torah prohibits using what grows in violation of the kil’ayim prohibition. Other kil’ayim mitzvos prohibit only the act, but what grows or develops as a result may be used. (The Yerushalmi, Kil’ayim 1:4, permits using even the cutting developed from a forbidden graft.)

There is a major dispute among tana’im and rishonim whether kil’ei hakerem applies even when planting one species other than grapes in a vineyard, or only when two species other than the grapes are planted in a vineyard. Rav Yoshiyah rules that the lo sa’aseh of kil’ei hakerem applies only when planting both wheat and barley (or any two other species that are kil’ayim with one another) in a vineyard. Since the Torah says, “You shall not plant kil’ayim in your vineyard,” Rav Yoshiyah understands this to mean that someone is planting two varieties that are kil’ayim with each other, in a vineyard, which compounds the prohibition.

Vineyard vs. vines

There are major halachic differences between a few grapevines and what is halachically called a vineyard. The most prominent difference is that it is prohibited to plant any type of grain or most vegetables within four amos (about seven feet) of a vineyard, whereas it is forbidden to plant only within six tefachim, which is less than two feet, of a grapevine that is not part of a vineyard.

What is a vineyard?

So, what is a vineyard?

The halacha is that a vineyard must have at least five grapevines growing, four of which are positioned in a rectangle or square. Exactly how the fifth vine is planted is unclear from the Mishnah (Kil’ayim 4:6), and is disputed by the halachic authorities. The Chazon Ish rules that a vineyard requires that the fifth vine continues in a straight line from two of the other vines. In other words, the minimum definition of a vineyard is two parallel grape plantings, one of at least three plantings and the other of at least two.

Others contend that the fifth vine can also be similar to the way one would envision, from a bird’s eye view, the location of the tail relative to the four legs of an animal standing in rapt attention. The four legs form a rectangle, and the tail is alongside the rectangle, but opposite the middle of a side rather than the continuation of one of its sides (Rambam, Peirush Mishnayos, Kil’ayim 4:6; Tosafos Yom Tov; cf., however, Rambam, Hilchos Kil’ayim 7:7).

If five vines have been planted this way, and alongside them many more vines were planted haphazardly, the disorganized vines might not be considered a vineyard, but individual vines. The practical difference is whether vegetables and grains may be planted nearby, as long as they are more than six tefachim from the vines, or whether the laws of a vineyard apply, which requires a much more substantive distance of four amos. In both instances, construction of a tzuras hapesach or other mechitzah will allow planting the vegetables or grains alongside the vines, as long as the mechitzah separates between the vines and the vegetables or grains.

One row of grapevines is not considered a vineyard, even if it contains hundreds of plantings (Kil’ayim 4:5). This means that one may plant vegetables or grains alongside the grapes, as long as there is a six tefachim distance between them.

Kil’ei hakerem in chutz la’aretz

The rules of kil-ei hakerem in Eretz Yisrael are stricter than they are in chutz la’aretz. In chutz la’aretz, there is a rule, kol hameikil ba’aretz, halacha kemoso bechutz la’aretz. For our purposes, this rule means that since the law of kil’ei hakerem in chutz la’aretz is only miderabbanan, Chazal ruled that whenever a recognized scholar ruled that a particular situation is not considered kil’ayim in Eretz Yisrael, even when the halachic conclusion rules against him, one may follow this minority position in chutz la’aretz. For example, since Rav Yoshiyah rules that kil’ei hakerem is prohibited only when planting two species (that are already prohibited together) in a vineyard, this is the only act of kil’ei hakerem prohibited in chutz la’aretz. However, in Eretz Yisrael, there is concern over planting even a single type of vegetable in a vineyard.

Kil’ei zera’im

Kil’ei hasadeh or kil’ei zera’im (two ways of referring to the same prohibition) is planting two non-woody (also called “herbaceous”) commonly cultivated plants or seeds near one another, planting one species very close to another, already-planted species, or planting the seeds of one species on top or inside a specimen of another species. This mitzvah applies only in Eretz Yisrael. In chutz la’aretz, it is permitted to plant two herbaceous plants next to one another, although some authorities prohibit planting the seed of one species on top of or inside another in chutz la’aretz (Rambam, Hilchos Kil’ayim 1:5; Tosafos Chullin 60a s.v. Hirkiv). Therefore, in Eretz Yisrael, someone planting a garden patch must be very careful to keep the different species separate.

Both prohibitions, kil’ei hakerem and kil’ei zera’im exist, even if the species are not intentionally planted together, but grew on their own (Kil’ayim 2:5). In this instance, if the two species are too close together, one either must pull out one, or, as we will see shortly, build a mechitzah between them.

Introductions

Several important introductions will facilitate understanding the laws of these mitzvos.

A. Firstly, many assume that kil’ayim prohibits hybridization or crossbreeding (two ways of saying the same thing) of unlike species, or, in simpler terms, attempting to mix genetic material and create new species. However, this approach is inaccurate, since only one of the many kil’ayim prohibitions, crossbreeding animals, attempts to create something that does not occur in nature. All the other mitzvos ban the appearance of mixing two species. This distinction is very important in understanding many of the laws of kil’ayim.

B. Secondly, for clarity’s sake, I will use the word “species” in this article to mean items that halacha prohibits “mixing.” The dictionary definition of the word “species” is “a pool of individuals that breed together and will not breed with other individuals.” However, neither halacha nor science uses this definition. Since this article is a halachic talk about kil’ayim, I will discuss only aspects of the halachic definition germane to these mitzvos.

What defines a halachic species? Although there is a great degree of uncertainty about this, certain principles can be derived from the various passages, particularly of the Talmud Yerushalmi Kil’ayim.

(1) Two varieties that naturally cross-pollinate are halachically considered one species (see Yerushalmi Kil’ayim 1:2).

(2) At times, similarity of leaves or appearance or taste of the fruit are sufficient evidence to consider two varieties as members of the same species (Yerushalmi Kil’ayim 1:5). Small differences are never considered significant (Bava Kama 55a). Thus, different varieties, one of which grows wild and the other of which is cultivated, are usually one species (Mishnah Kil’ayim 1:2). Frequently, the rules are difficult to define and, therefore, most authorities recommend not growing two similar varieties of squash or beans together.

C. It is also important to note that the definition of “species” for the laws of kil’ayim is not the same as it is for the laws of challah. Spelt and wheat are considered different minim for the laws of kil’ayim, notwithstanding that they are the same min for the laws of challah. (This means that dough made of spelt and wheat flour can combine to create enough dough to be obligated to separate challah, notwithstanding that wheat and spelt cannot be planted next to each other.)

Cultivated

D. As I mentioned above, kil’ei zera’im and kil’ei hakerem apply only to species that are cultivated or maintained in your location for food, forage, clothing, dye or other similar purposes. The Mishnah states that the laws of kil’ayim apply to a species called zunin,usually understood to be darnel, a ryegrass that, in earlier generations, was used as bird seed. Planting zunin in a field of barley, rye, oats or spelt violates the prohibition of kil’ei zera’im. (Why it is permitted to plant zunin in a wheat field [Mishnah Kil’ayim 1:1] is a topic that we will leave for a different time.)

Proximity

Planting two crop species together or near one another is prohibited as kil’ayim. How far apart the two species must be depends on several factors, including the layout of the planting and what and how much was planted. In some situations, when growing small amounts of certain vegetables, planting the two species in alternate patterns is sufficient to permit the planting, notwithstanding that the different species grow alongside one another (Kil’ayim 3:1; Shabbos 84b ff.).

Between two grain fields of different species — for example, one growing spelt and the other rye — there needs to be an empty area greater than ten amos squared, approximately twenty feet by twenty feet, between the two fields. On the other hand, between two kinds of vegetables, the requirement is that the separating area be only six tefachim squared, approximately two feet by two feet. And even the size of this requirement is only miderabbanan. Min haTorah there is a dispute among rishonim whether the distance is one tefach squared, or 1.5 tefachim squared (Raavad, Hilchos Kil’ayim). The Chazon Ish (5:1) ruled according to the Rambam, the lenient opinion, that requires only one tefach squared, approximately four inches by four inches.

Mechitzah

Although we usually think of mechitzah as a separation necessary in a shul, the word has significance in several other areas of halacha, and particularly in the laws of kil’ayim. For the purposes of kil’ayim, whenever one wants to plant two species and there is not enough space to allow this, a halachically acceptable separation between the plantings permits the planting (Kil’ayim 2:8; 4:6). The rules here are similar to what is called a mechitzah for other halachos, including permitting carrying on Shabbos, although, for the laws of Shabbos, the entire area must be enclosed by mechitzos on all sides. For the laws of kil’ayim, it suffices that there is a halachic divider separating the plantings from one another. Among the many ways that someone can separate the two areas is by building a wall that is ten tefachim tall (approximately 32-40 inches) or piling rocks to a height of ten tefachim. Another option is a furrow or crevice in the ground, either natural or dug, that is ten tefachim deep.

The Mishnah (Kil’ayim 4:4) notes that lavud, openings that are smaller than three tefachim (about ten inches), does not invalidate a mechitzah, and therefore a fence that is more open than closed, but is ten tefachim tall, is a valid mechitzah for kil’ayim purposes. Similarly, one may build a “wall” with sticks placed either horizontally or vertically every three tefachim, and it is a satisfactory mechitzah.

This means that someone may have a vineyard on one side of a fence, in which the grapes grow alongside the fence, and plant grain or vegetables on the other side of the fence; it is completely permitted, even though the two crops may be growing within inches of one another.

Gaps

Large gaps in the middle of a mechitzah may not invalidate it. The general halachic principle is that an area that is mostly enclosed is considered “walled,” even in its breached areas (Kil’ayim 4:4; Eruvin 5b). For example, a yard enclosed by hedges tall enough to qualify as halachic walls may be considered enclosed, notwithstanding that there are open areas between the hedges, since each side is predominantly enclosed either by the hedges or by the house. This is true as long as the breach is smaller than ten amos,about 17 feet (Kil’ayim 4:4). This means that someone may have a vineyard on one side of the hedges (inedible growths usually do not create prohibited kil’ayim), and grain or vegetables on the other side of the hedges, even though the two crops may be extremely close to one another.

Tzuras hapesach

The Gemara (Eruvin 11a) rules that a tzuras hapesach, which we customarily use to make to enclose an area to permit carrying on Shabbos, may be used to separate two species, so that there is no prohibition of kil’ayim. A tzuras hapesach consists of two vertical side posts and a horizontal “lintel” that, together, vaguely resemble a doorway. Thus, it is permitted to grow a vineyard on one side of the tzuras hapesach and grain or vegetables on the other side.

Weeding

What about weeds? Do weeds present a kil’ayim concern?

As anyone who gardens knows, the definition of a “weed” is whatever the gardener does not want in his garden. Halachically, if the “weed” is from a species that is not maintained in your area, it is not a kil’ayim concern.

Conclusion

Targum Onkelos (Vayikra 19:19 and Devarim 22:9) understands the word kil’ayim to mean “mixture.” However, other commentaries explain the origin of the word from the Hebrew root כלא, the same as the word beis ke’le “prison” (see Bamidbar 11:28). Rav Hirsch (Vayikra 19:19) explains that the root כלא means to hold something back, and that the plural form kil’ayim — similar to yadayim, hands, or raglayim, feet — means a pair. Therefore, the word kil’ayim means to pair together two items that should be kept apart.

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 kil’ayim helps us remember how various species obeyed Hashem’s instructions to remain separate during their creation. This reminds the contemplative Jew that if the plants heeded Hashem’s word during the Creation, how much more are we obligated to obey His instructions!

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:

1. 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:

1. 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).
2. 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.
3. 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).
4. 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.