3,075. One Who Doesn't Trim His Trellis

Hilchos Kilayim 6:14

If reeds stick out from the lattice of a trellis, but the owner doesn’t want to remove them because it will destroy the trellis, he may plant seeds under them. If he left the reeds so that the branches and leaves of the vine will grow on them, then he may not plant under them.

Hilchos Kilayim 6:15

If a branch sprouts from a vine that is being supported, or from the trunk of a vine that is not being supported, we act as if a plumb line (i.e., a vertical weight) hangs from it to the ground and it is prohibited to plant under it. Similarly, if one extends a branch from tree to tree, it is prohibited to plant under it.