Whatsoever is subject to the obligation of pe’ah is also subject to that of tithes; but there is a kind of produce which is subject to the obligation of tithes and is not subject to that of pe’ah.
The obligation of pe’ah – literally “corner” – that requires leaving a part of the field for the poor to harvest, is based on the passage in Sefer Vayikra (19:9) “When ye reap the harvest . . . thou shalt not wholly reap the corner of thy field . . . thou shalt leave them for the poor.”
The Gemara teaches that there are a number of general principles concerning pe’ah:
“Whatsoever is a foodstuff, is kept under watch, grows from the ground, is all harvested at the same time, and is taken in for storage is subject to pe’ah.”
Each of these rules limits the obligation of pe’ah such that the Gemara teaches:
‘A foodstuff,’ excludes the after-growths of woad and madder;
‘is kept under watch,’ excludes hefker ;
‘grows from the ground,’ excludes morils and truffles;
‘is all harvested at the same time,’ excludes the fig-tree;
and ‘is taken in for storage,’ excludes vegetables.
Regarding tithes, however, the Gemara teaches:
Whatsoever is a foodstuff, is kept under watch and grows from the ground is subject to the obligation of tithes.” The rules requiring that harvest take place at the same time and that it is taken in for storage are not mentioned.
Thus, figs and vegetables are not subject to the requirements of pe’ah.
The reason that figs are not considered a fruit whose harvest takes place at the same time is because figs are unique in that they do not all ripen on the tree at the same time. Every day – and even at different hours throughout the day – individual fruits will ripen based on how heat and sunlight hits the tree. For this reason it is commonplace to find that the fruit on the eastern and southern parts of the tree are harvested first, since they get the most direct sunlight.