Sefer HaChinuch ספר החינוך

To not plant forbidden mixtures in a vineyard: To not plant types of grain in a vineyard, and [also] not hemp or arum (loof). And this type of forbidden mixtures is called forbidden mixtures of the vineyard (kilayei hakerem). And about this is it stated (Deuteronomy 22:9), “Do not plant your vineyard a forbidden mixture.” And they, may their memory be blessed, said (Sifrei on this verse), “[Why] do I need this, is it not stated (Leviticus 19:19), ‘your field you shall not plant a forbidden mixture?’ It teaches that anyone who keeps a forbidden mixture in his vineyard transgresses two negative commandments.” And they, may their memory be blessed, explained (Kiddushin 39a) that forbidden mixtures of the vineyard are two types of grain seeds with grape seeds. And this is what Rabbi Yeshayah said, “He [has not transgressed] until he plants wheat and barley and grape-seed in one fall of the hand,” as this is what is implied to them by “forbidden mixtures in a vineyard,” meaning to say that you need a forbidden mixture besides “your vineyard.”

I have written regarding the commandment of cross-breeding in the Order of Kedoshim Tehiyu (Sefer HaChinukh 244) from the roots of the commandment of forbidden mixtures from the angle of its simple meaning (peshat) as is my custom, and take it from there. And we still need to speak here [about] what the reason is for the new [aspect] of the prohibition, that we need for it a forbidden mixture besides the vineyard. And maybe we shall say that it is from the vineyard being a very important thing and having a very strong nature, that one other type together with it would always be negated and [so] it would not be considered as a forbidden mixture or as anything. And therefore, the verse required two types besides the vineyard. And maybe from the strength of this explanation, we shall also say that the two types that the verse required must be types of grain, which are important for their functions, [just] like hemp and arum, which are important for their functions. But all other types would be negated with the grapevines and are not forbidden by the Torah but only rabbinically.

From the laws of the commandment is that which they, may their memory be blessed, said (Menachot 15a) that the Torah’s prohibition of a forbidden mixture of the vineyard is only in the case of types of grain and hemp and arum, but to plant vegetables and other types and grape-seed is [only] forbidden rabbinically. And so [too] did the Rabbis forbid to plant types of grain and also vegetables alongside the grapevines, or to plant a grapevine alongside the vegetable or the grain, because of the concern of interbreeding. Since the grapevine is softer than all other trees, they were more concerned about it. And if he did this — even though he is not lashed — behold, he set [it] apart and it is forbidden to benefit from both of them, and we burn the whole thing. And [we burn] even the chaff of the grain and the wood of the grapevines, as it is stated, “lest it be set aside (tikdash), the crop, the seed, etc.” — and they, may their memory be blessed, expounded (Kiddushin 56b), “Lest it be incinerated by fire (tukad esh),” meaning to say that all of it is fitting to be burnt, as we will write adjacently (Sefer HaChinukh 549). And the rest of its details are elucidated in Tractate Kilayim. (See Tur, Yoreh Deah 246.)

And the prohibition of forbidden mixtures of the vineyard from Torah writ is practiced by males and females in the Land of Israel alone, and rabbinically even outside of the Land. And even though forbidden mixtures of seeds are not practiced outside of the Land even rabbinically, we have already elucidated in the Order of Kedoshim (Sefer HaChinukh 245) that they, may their memory be blessed, were stringent with forbidden mixtures of the vineyard to forbid them outside of the Land, since they are so weighty that [even] their benefit is forbidden in the Land, as this reason is explained in the end of the first chapter of Kiddushin 39a.

One who transgresses this, and planted wheat and barley and grape-seed in one fall of the hand in the Land [of Israel], is lashed immediately when he plants them from Torah writ; and outside of the Land, he is rabbinically struck with lashes of rebellion. But concerning the matter of their benefit becoming forbidden, they are not forbidden immediately when he plants them, until after it has taken root, and as they, may their memory be blessed, said (Pesachim 25a), “[If] it is planted from its start, with the taking root; [if] it has already been planted and increases, with the [further] increase.”