Item extentions

I am making a mod that requires me to use the trigger (onPlantTick) and to add a property to an item.
the problem is, when I select item extension, it has very little things you can do, and I don't see anything in the global events about plants at all.
Right now, the only thing I can think of doing, is to use the global (bonemealUsed) trigger, and do it that way. Though that is not ideal.