Has anyone tried the Herbio spell on those planter boxes? (Just checked it myself. The only spell available on those planter boxes is Inferniate.)
Judging by the original neighborhood gardens in Willow Creek and Oasis Springs, the planter boxes should already have plants and they should be tended by an NPC gardener. Going all the way back to 2014, I'm sure that I've never been able to plant anything in the neighborhood planter boxes or provide any care for the plants in them. I've always been limited to harvesting, taking cuttings, and collecting microscope samples. With a spellcaster, I can use Floralorial on plants that need tending, Copypasto on the harvestables, and Inferniate.
To sum up, the answer is No. That community garden in Mt. Komorebi is not supposed to be usable.
