The CropGrowPre Event is fired when crops attempt to grow. It has a result which determines whether the default behaviour occurs or not:

• allow: the crop is forced to grow.
• deny: the crop is prevented from growing.
• default: the attack uses default Vanilla behaviour.

You will need to cast the event in the function header as this class:
crafttweaker.event.CropGrowPreEvent
You can, of course, also import the class before and use that name then.

CropGrowPost Events implement the following interfaces and are able to call all of their methods/getters/setters as well:

• IBlockEvent
• IEventCancelable

The following information can be retrieved from the event:

ZenGetter	ZenSetter	Type
ZenGetter originalBlockState	ZenSetter ​	Type IBlockState
ZenGetter originalBlock	ZenSetter ​	Type IBlock