Yes the block walls on the sides are underground, block wall on the back is sepereating the garage from the basement. The veg room will be against one of the outside block walls (underground) and the basement seperating block wall to the basement.Go with a small unvented propane heater with a thermostat just the pilots on them put out 1000 btu, So those block walls are underground?
Will look into the propane heater but worried it might be to large for the 10x10 area which will be prety full with plants.