Kilayim, Chapter Five, Mishnah Six
As we learned in yesterdays mishnah, kilayim is caused not just when a person plants seeds in a vineyard, but also when one sees seeds and allows them to continue to grow. Our mishnah discusses how immediately a person must uproot the seeds that he sees growing in his vineyard.
1) One who sees a vegetable in a vineyard, and said: When I reach it I will pluck it, it is permitted.
2) [But if he says:] When I come back I will pluck it, if [the vegetable] has [in the meantime] increased by a two-hundredth, it is forbidden.
Section one: If while tending to the vineyard he sees the vegetable growing in the vineyard and says that he will pluck it when he gets to it, the vines have not become prohibited. This is true even if the vegetables grow in the meantime. Since he was not actually lazy and only said that he would pluck the vegetables when he got to them in his rounds through the vineyard, he is not penalized.
Section two: However, if he was near the vegetable and then said that he will pluck it when he gets back to it, then the vines will become prohibited if the vegetable grows 1/200 in the meantime. In other words, for the vines to become prohibited the vegetable has to grow a minimum amount of time after the moment that he first noticed it. Since he could have plucked them when he was there, he was lazy and the kilayim prohibition goes into effect.
Interestingly, the amount it grew before he even noticed it does not cause the vines to become prohibited. We see here that the mere existence of kilayim doesnt cause a prohibition. Rather there must be human involvement, either by planting the seeds in the vineyard or noticing them and allowing them to stay there. This will become even more obvious when we learn tomorrows mishnah.