Hi, I'm messing around writing quests for the mod, and ended up testing growing the plants in the planter. All of these tests were done on full grown plants.

Right clicking with the Athame on the Sprig of Avenna while it's in the planter destroys the Sprig with no drops.

Doing the same to the other three plants plays the shears sound but doesn't affect the block or drop any items. My expectation was that right clicking the Athame on mature plants in the Planter would produce a drop of the plant's item and revert the age of the planted plant to 0.