Kilayim 5:4

If a grapevine is planted in a wine vat or in a cleft of the field, one must leave a space of six handbreadths (about 18 inches) and he may then plant in the rest. Rabbi Yosi says if there aren’t four cubits (about six feet), one may not plant there. One may plant in a house that is situated in a vineyard.

Kilayim 5:5

If one plants vegetables in a vineyard – or if he keeps vegetables that grew there on their own – he causes 45 vines to become prohibited because of mixed species. This is the case when the vines are planted only four or five cubits apart; if they are planted six or seven cubits apart, then he only renders prohibited the vines within sixteen cubits on all sides. The perimeter drawn is a circle rather than a square.