When starting a farm, if the farmhands/slaves do not have enough seeds, they will plant all of the seeds they have and then stop farming (except for tilling dirt/grass). Even once the crops grow, they will not harvest them (even if harvesting would replenish their seeds).
A solution to this would be to have farmhands keep their last seed and not plant it until they get more seeds. This would mean that they can initially only plant 63 plants instead of 64, but the player does not need to go around the field giving each farmhand more seeds later.
This would also make pumpkins and melons farmable. Currently, farmhands/slaves will fill the entire field with pumpkin/melon plants and not leave any room for the actual pumpkin/melon to grow. Players could plant vines with space between them, then give each farmhand/slave one pumpkin/melon seed, and they would harvest any pumpkins/melons that grow, without planting new vines that would get in the way.