Both Green Thumb spell and Magical Mulch do nothing programing wise in game.
I can confirm they do nothing on multiple applications of both spells now and have not received double herbs from Green Thumb or increased herbs from Magical Mulch. Both of these are programmed to increase yields of plants with each application and Green Thumb is supposed to double the amount gathered out right and does nothing.
Feels bad when you have Luredrop maxed out and still only get 2 of the lowest quality when gathering from a Lush node. While using Green Thumb. So that LUSH node was only going to drop 1? at poor quality?? Lush nodes should have a minimum quantity/quality drop rate, otherwise what’s the point of it being ‘Lush’?
Honestly, I never understood how using green thump can make you gather an odd number of herbs (excluding finesse).