3,409. Buying Detached Produce to Eat

Hilchos Maaser 4:18

If coriander is planted in a courtyard, leaves may be picked and eaten one at a time. If one collects them, they must be tithed. The same applies in all comparable cases.

Hilchos Maaser 5:1

If someone buys detached produce to eat, he must tithe it by Rabbinic enactment as has already been discussed. This obligation comes into effect when the buyer pays, even if he has not yet brought the produce in. If a buyer is choosing produce and putting aside a bit at a time, he is not obligated to tithe it even if he does this all day long and has decided to buy it. A God-fearing person will tithe produce once he decides to purchase it and if he later wants to return it, he may do so.