Taking teruma and ma’aser when picking a few fruits at a time
Question
I have a tangerine tree in my backyard for seven years now. This year the tree yielded a lot of fruit, B”H. Do I have to take ma’aser each time I pick a certain amount of tangerines?
Answer
Each time you pick fruit, you need to set aside terumot and ma’aserot, unless the fruit is eaten outside one at a time. If, however, you bring the fruit into the house, you are obligated to take terumah and ma’aser each time. How wonderful it is that you have the privilege of eating the delicious fruit of the Land of Israel and performing its special mitzvot!
However,
If it is difficult to separate terumot and ma'aserot each time -- and especially if there is a concern that family members will eat the fruit without tithing, there is a way to separate in advance once a week against each week's harvest. Please see Rabbi Moshe Bloom's explanation of the procedure here.
The formula for this separation appears on p. 16 of our guide, Mitzvot of the Land in a Nutshell
Note that advanced separation is not lechatchilah; it's best to actually separate each time you harvest
.