I noticed that villagers had planted seeds on a piece of land that I had accidentally hoed. The plants grew. I then tested this myself on land that was four blocks above the normal ground surface thus without any water source. If I planted seed prior to the farmland going back to earth then all plants grew successfully.

This may not be connected but I also hoed all the paths in a village that I had destroyed - because it is now the easiest way to get rid of paths, and I noticed the quite a few random blocks had become saturated although not near a water source.

I have searched for issues on this subject but couldn't find any.