Kilayim, Chapter Four, Mishnah Seven
This mishnah deals with a person who plants one row of vines on his own land and one row on anothers. The question is whether these two rows combine to be a vineyard.
1) One who has planted one row [of vines] on his own [land] and another row on his neighbor’s [land], and there is a private road or a public road in the middle, or a fence lower than ten handbreadths, these [two rows] combine.
2) If there is a fence higher than ten handbreadths they do not combine.
a) Rabbi Judah says: If he intertwines them [the rows of vines] above [the fence] they do combine.
Section one: The mishnah rules that the vines join together to form a vineyard even if they are separated by either a private road or even a public road. Similarly, a fence that is lower than ten handbreadths will not separate the two vines. In such a case, before he can plant seeds near these vines he will have to leave a distance of four cubits around the vines in order to tend to them.
Section two: However, if the fence is higher than ten handbreadths, then the two vines do not join to constitute a vineyard.
Rabbi Judah adds in that if he intertwines the vines on top of the fence, then they do join together to form a vineyard.