but on wiki https://ringofbrodgar.com/wiki/Farming there are two other different values:
2 hours:
Each batch of a crop which is planted in the same area (~2 minimaps), time (~2 hours), and of the same type (carrots, peas, barley, etc), will be given the same random quality modification uniformly, and planted tiles of that batch will thus all have their quality affected in the same way.
and
5 hours:
Planting in three phases, at least 5 hours apart will give you three chances to score the +5.
Does anybody know for sure which one is right?