Orlah 1:4-5

Orlah 1:4

If a tree got uprooted but one root remained connected, it is exempt from orlah. Rabban Gamliel said in the name of Rabbi Elazar ben Yehuda of Bartoa that the amount of root necessary to effect this exemption is the width of a weavers’ pin.

Orlah 1:5

If a tree got uprooted but a branch was bent into the ground and nourished it, then the tree becomes like that branch (i.e., not obligated in orlah so long as the branch remains in the ground). If the owner sinks another shoot from that branch, and each year he sinks another shoot, and then the branch gets detached, he counts the orlah period (three years) from the time the branch got detached. If one grafts grape vines or branches together, the fruit is exempt from orlah even if sunk into the ground (because all of them are connected to an exempt plant and are not considered newly-planted). Rabbi Meir says that when the grafts draw sufficient nourishment from the original plant, orlah does not apply; when the grafts do not draw sufficient nourishment from the original plant (so the new extension requires the nourishment the soil provides), orlah does apply. Similarly, if a shoot of the vine sunken in the ground is full of fruit and gets detached, if it increased by 1/200, the laws of orlah apply (because orlah is only cancelled out by a ratio of 1 in 201 parts, so 1 in 200 is insufficient).