1st. Make sure that you build a farm etc. on a default stamped realm, THE WHITE CLOUDY default stamp.
2nd. Don't Put a block on top of your crops ( I'm talking about any block height ) There should be NO blocks above and beyond your crops.
3rd. Idk if this affects your crops but MAKE SURE U PUT DIRT BELOW the Farm Soil.
4th. Read this 3 rules again XD
ANOTHER THING. Make sure that you are just Farming in one of your realms if your ( LAND MANAGER PERK IS JUST LVL 1 )