According to most Rishonim and Aḥaronim, the prohibitions against grafting trees and breeding animals of different species apply to Bnei Noaḥ as well, although they are not among the Seven Laws of Bnei Noaḥ. The verse states: “You shall keep My statutes” (Vayikra 19:19), and the Sages derive from this: “The statutes that I already engraved for you” – even before the giving of the Torah – “you must now keep.” Similarly, the Torah states: “The earth brought forth vegetation: seed-bearing plants of every kind, and trees of every kind bearing fruit with the seed in it. And God saw that it was good” (Bereishit 1:12). From here we learn that these statutes are binding on Bnei Noaḥ as well (Sanhedrin 60a; She’iltot; Behag; Rambam; Riaz; Vilna Gaon; Arukh ha-Shulḥan; Rav Kook).
Others disagree and maintain that Bnei Noaḥ are not prohibited from grafting trees or breeding different animal species (Ritva, Rosh, and Radbaz). Even according to this view, however, a Jew may not ask a gentile to graft his tree or breed his animal. Just as a Jew may not ask a gentile to violate Shabbat on his behalf, he likewise may not ask him to perform other Torah prohibitions involving his property.
Even according to the stringent view, the prohibition may apply to Bnei Noaḥ only when the grafting is certainly prohibited. However, when there is uncertainty about the graft’s halakhic status – for example, when the rootstock and scion may be two varieties of the same species – Bnei Noaḥ are not prohibited from performing the graft (see Mishpat Kohen 13).[5]
By contrast, Ritva (Kiddushin 39a), Rosh, Radbaz, and Shakh (YD 297, second §3) maintain that the halakha follows the Sages and that a Ben Noaḥ is not prohibited from grafting a tree. Nevertheless, even according to them, the Sages prohibited a Jew from telling a gentile to graft a Jew’s tree, based on the law of amira le-goy, instructing a gentile to perform a prohibited act. This is also called shevut be-sh’ar issurim, a rabbinic restriction against asking a gentile to perform other Torah prohibitions. We have learned that a Jew may not ask a gentile to do for him an act that the Torah forbids the Jew himself to perform. In Bava Metzia 90a, the Sages were uncertain whether amira le-goy applies even to a Torah prohibition that does not carry the death penalty. Because of this doubt, most Rishonim ruled stringently, as explained in Peninei Halakha: Shevi’it 5, note 9. Based on this, Radbaz writes that one may ask a gentile to graft a tree if the intention is that afterward the Jew will buy the grafted tree from him and plant it (Radbaz on MT, Laws of Kilayim 1:6). As explained in the next note, according to Ritva and Radbaz, one may plant it even before the graft has fused. According to most poskim, this is permitted only after it has fused, while some are stringent and prohibit it.
However, according to most poskim, one may not ask a Ben Noaḥ to perform an act of grafting that is prohibited even when he is grafting his own trees, because asking him to do so causes him to violate a prohibition. When the grafting itself is doubtful, however, one may be lenient. First, it seems likely that for Bnei Noaḥ the prohibition applies only when the grafting is clearly prohibited, with no uncertainty. Even if we do not accept this, in a case of doubt there is effectively a safek sefeka, a double doubt, since we may also include the view that Bnei Noaḥ are permitted to graft trees altogether (Ḥazon Ish, Kilayim 1:1). For trees about which there is no such doubt, there would seem to be no solution. Nevertheless, it appears that one may be lenient with bench grafting – grafting dormant cuttings while they are detached from the ground. Only after they have been joined is the rootstock placed where it can take root. Since this form of grafting resembles hybridization and artificial insemination, it may not be prohibited, because it is performed while detached from the ground (see R. Yoel Friedman’s article in Emunat Itekha 92). Even if we are concerned that bench grafting is prohibited for Jews, it is permitted for Bnei Noaḥ on the basis of a safek sefeka. After the sapling has fully fused, it may be planted according to most poskim, as explained in the next section.
