Planting Different Species Together (Kilayim)
I am planning to plant a garden this spring and would like to know what restrictions apply in terms of planting different species together and the like.
The Aish Rabbi Replies
There are a number of Torah prohibitions which apply to “mixing” different types of plants. They are part of a more general prohibition against mixing different items – which includes interbreeding different species of animals and wearing a garment which contains both wool and linen. (The mixed items are referred to as kilayim, based on the Torah’s language.) The main prohibitions relevant to plants are mixing different seeds (Leviticus 19:19), grafting unrelated trees (derived from Leviticus 19:19), and planting near a vineyard (Deut. 22:9).
Many of these prohibitions only apply in the Land of Israel. Since you are writing from the Diaspora, I will write the rules as they apply to you:
(1) There is no restriction with planting different seeds next to each other. That only applies in the Land of Israel.
(2) We may not plant food-bearing plants next to a vineyard. There must either be a fence between them, or for a vineyard there must be a separation of four cubits (about two meters) and for a single vine half a meter.
(3) We may not plant food-bearing plants immediately adjacent to any fruit tree. The distance must be 3 handsbreadths (about 10 inches) from the roots of the tree (meaning, the farthest root which sticks out above the ground).
(4) We may not graft a branch of one tree onto a tree of a different species.
See also this response regarding fruit trees for their first four years.)
(Sources: Leviticus 19:19, Deuteronomy 22:9-11, Talmud Kiddushin 38-9, Rambam Laws of Kilayim 1:3-6, 7:1, Laws of Forbidden Food 10:19-10, 15. Shulchan Aruch Y.D. 295:3, Shach 2, Taz 2, Aruch HaShulchan 8,10.)