3,265. Taking Terumah for Produce Still Attached to the Ground
Terumos 5:8
One may not take ritually unclean produce as terumah for ritually clean produce. If one did so accidentally, what he separated is terumah; if he did so intentionally, what he took is terumah but he doesn’t fulfill the obligation for the rest of the produce, with the result that he must take terumah again. This is only the case when he’s unaware of the ritual impurity. If he’s aware of the impurity, but he thought it was permitted to take ritually unclean produce terumah for ritually clean produce, then it’s as if he acted intentionally. The same rules apply when it comes to terumas maaser.
Terumos 5:9
One may not take produce that is still attached to the ground as terumah for produce that has been picked, nor vice versa. Accordingly, if a person has detached produce and he declares it terumah for produce that is still attached to the ground, even if he says that it will take effect once that produce is picked, his words are ineffective. This is also the case if he has two rows of produce and he declares produce of the detached row to be terumah for the attached row, or vice versa. However, if he declares the produce of the detached row to be terumah for the other row once it’s picked, and that produce is later picked, his words are effective once they are both detached because he had the ability to pick it. This is the case so long as the produce had reached a third of its growth when he made his declaration.