I wouldn't be without them. There's four in the roof of my big 16ft x 8ft greenhouse. On hot days, like now, I'll leave the double doors open, and both of the low-level 'louvre-vents' open too, and it can still reach temperatures to kill a plant.
I don't think that ventilation should be overlooked at all in the health and well-being of plants. Ventilate as much as possible...... |