Kilayim 2:7-8

Kilayim 2:7

If the point of a wheat field extended into a barley field, this is not kilayim because the point clearly delineates the end of the field. If one person has a wheat field and his neighbor has a field sown with another crop, he may plant the same species close to his neighbor’s field. If his field is wheat and his neighbor’s field is also wheat, he may plant a row of flax but not another species. (This is because flax is not profitable, so he clearly planted it just to test his field. Another crop would be seen as desirable and therefore kilayim.) Rabbi Shimon says one may not even do this with flax seed. Rabbi Yosi says that one may test his field with a row of flax even in the middle.

Kilayim 2:8

One may not plant mustard or safflower near a field of grain but he may plant them close to a field of vegetables. (It would not be kilayim in the latter case because it’s bad for the vegetables and therefore undesirable.) One may plant near a fallow field or next to a plowed field, as well as next to a wall, a road, a fence that is ten-handbreadths tall, a ditch that is ten handbreadths deep and four handbreadths wide, a tree whose branches hang within three handbreadths of the ground, and a rock ten handbreadths tall and four handbreadths wide. (All of these things constitute a separation between the crops planted on either side of them so that they will not be kilayim.)