Kilayim, Chapter Six, Mishnah Three
This mishnah deals with one who hangs vines over a trellisthe question is can he plant seeds under the parts of the trellis not covered with vines.
1) One who suspends vines over papyrus-ropes [of a trellis], he may not bring seed beneath the remainder [of the trellis].
2) However, if he did so, he has not caused them to be prohibited.
3) If new [tendrils] spread [over the remainder], that [which was sown under the remainder] is forbidden.
4) Similarly, when one hangs vines over some part of a non-fruit-bearing tree.
Section one: It is forbidden, ab initio, to sow seeds underneath a trellis with vines trained over it, even underneath the parts that dont have vines on them.
Section two: Although one is not allowed to plant seeds underneath the trellis, if he does do so, he has not caused the seeds to be prohibited. This is because he has not sown the seeds underneath the vines themselves.
Section three: If, contra to the rules, he does sow seeds underneath the trellis when there are no vines directly overhead, and then the vines do grow over those seeds, the seeds underneath the vines now become prohibited.
Section four: The same rules that apply above also apply when one hangs vines over a non-fruit bearing tree. The tree in this case is considered to be like a trellis because it does not bear fruit. In tomorrows mishnah we will learn that the rule is different when the tree does bear fruit.