3,266. The Current Year and the Previous Year

Terumos 5:10

One may not take fresh produce as terumah for dried produce, nor vice versa, but if one did so, what he separated is valid terumah. It follows that if he harvested a certain crop one day and then he harvested the same crop the next day, he may not take terumah for one from the other unless it’s a species that stays fresh for two days. Regarding something like cucumbers that typically stays fresh for three days, everything harvested in a three-day period can be combined and terumah taken from one for the others. If a certain species only stays fresh for one day and he harvested some in the morning and some in the evening, he may take terumah from one for the other.

Terumos 5:11

One may not take produce from the current year as terumah for produce from the previous year, nor vice versa. If he did so, what he separated isn’t terumah as per Deuteronomy 14:22, “From year to year.” Therefore, if one picked a crop before sundown on the day before Rosh Hashana and he picked another after sundown, he can’t take terumah from one for the other because one is the old crop and the other is the new crop. Similarly, if one picked an esrog before sundown on the day before the Tu b’Shevat and he picked another after sundown, he can’t take terumah from one for the other. The reason for this is because Rosh Hashana is the new year when it comes to tithing grain, legumes and vegetables, while Tu b’Shevat is the new year when it comes to the tithes of trees.