Personally, I'd move or scrap the grow because if it's that bad, you're gonna fight powdery mildew and bud rot and probably lose the grow anyway.
Otherwise proceed at your own health risk.
Get a tube of low-odor silicone and a thick plastic sheet (6mil poly is good). Using the caulk, draw a perimeter around the affected area with a thick bead (I would include all along that whole baseboard) and then cover the area with the plastic, pressing it into the silicone sealing in all those danger spores. And realize that by sealing it in, you're also trapping the moisture and likely making the problem worse for when you do have to deal with it.
I've been there. Kinda. It wasn't a grow room.
Our first house, wifey called me at work, "Honey there are mushrooms growing out of the floor next to where you step into the shower.". WTF?!
Gutted the shower and surrounding area. The idiot that built the walk-in shower didn't use any membrane or even water resistant wallboard, it was tile on a 1-2 inch thick mortar mix on 1-2 inches of gravel on bare plywood subfloor.
Solution: shut off all plumbing to that bathroom, after tear out, wash down/soak everything in bleach/water solution, let dry, soak and let dry again then new subfloor, new wallboard (rockboard in the shower and blueboard for the surrounding area, shower pan kit, water-proof membrane from shower drain to ceiling, full-flex thinset, mosaic and subway tile and color-matched caulk in all corners. Even added a built-in shower seat in the corner.
Good luck!