Gardening - Forbidden Multi-Species Planting

QUESTION: Is there any type of planting that is forbidden in a vegetable garden (outside of Israel)?

ANSWER: Although we mentioned in the last Halacha Yomis that the prohibition of kilei zera'im – planting vegetables together is allowed outside of Israel, the Mishnah (Kilayim 1:7) writes that one may not graft trees together even outside of Israel. This applies not only to grafting two species of trees together, but even to grafting a vegetable plant and a tree together. Grafting is the act of placing one branch from one species of a tree or plant into the branch of another tree in a way that they will grow and fuse together.

The Shulchan Aruch (Yoreh De’ah 295:4) explains that the prohibition of grafting is not limited to actually grafting branches together, but even includes where roots of a vegetable plant penetrate into the branch of a tree and derive sustenance from the tree’s sap. This would also be considered grafting and be forbidden. This situation does not apply to planting on top of tree roots. It only applies to planting on top of tree branches. Chazal explain that this prohibition only refers to grafting with a tree. Grafting with the roots of a tree is not considered to have grafted with an actual tree. The Shulchan Aruch notes that since most tree branches are hard, we can assume that they will not be penetrated by the roots of a vegetable.

However, there is one common case of concern. Grape vines have soft branches, and it is common to bury their branches under the ground. If the vine branches are buried less than a foot under the ground, one may not plant another species on top of them. Since the vine branches are soft, they can be easily penetrated by another plant’s roots.

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The Gerald & Karin Feldhamer OU Kosher Halacha Yomis is dedicated to the memory of Rav Yisroel Belsky, zt"l, who served as halachic consultant for OU Kosher for more than 28 years; many of the responses in Halacha Yomis are based on the rulings of Rabbi Belsky. Subscribe to the Halacha Yomis daily email here.