It depends on your location and growing conditions. If your containers are out of doors in full sun with moderate air movement, then 10 to 12 inches is probably sufficient. If you are growing seedlings in a structure where air movement is limited, you may need to have your wire benches 16 – 24 inches above the floor. If you are seeing roots, even just small tips of roots extending a short distance out of the air-root-pruning openings, you do not have sufficient air circulations or height above the soil surface for your location.
You are here: