3,422. Planting Tevel
Hilchos Maaser 6:3
One may not cover untithed produce with soil, nor plant it. Even produce whose labors have not yet been completed may not be planted before tithing. This is the case with things like grain and legumes, but it is permitted to uproot a sapling that has fruit and to replant it elsewhere in one’s field. This doesn’t count as planting produce because he didn’t gather the fruit. Similarly, it is permitted to uproot turnips and radishes and replant them elsewhere if one’s intention is to increase their size. It is not permitted to replant them so that they’ll grow stalks from which he can take seed because that’s tantamount to planting untithed wheat or barley.
Hilchos Maaser 6:4
Let’s say that someone plants a litra (a measure of volume) of produce that was taken as tithes, but terumas maaser was not taken from it. If it grew to be ten litra, the whole crop must be tithed. One-tenth is taken from other produce for that first litra. If one tithed and planted a litra of onions, he doesn’t take tithes based on the increase, but based on the total size of the crop.