If you shine magenta light on a plant, it absorbs the whole ray so it appears completely black. The magenta light would be more dim than sunlight, but it would shine for longer and wouldn't fade like the sunlight on a cloudy day. There is no pest under ground so they don't need to use pesticides. At the surface there would be woods with cabins that are level with the tree canopy so it would be like a tourist resort.
I was impressed that after a long description, the artificial intelligence was able to draw an accurate image of one of my thoughts, now I'm sharing it with you the reader and my thoughts are playing out in your head so in a way, I'm closer to you than the air you're breathing right now.
I imagined a monarch or politician visiting my magenta plantation caverns and asking why the leaves on the trees are black? I would say they're not black, there is no green light for them to reflect.