Apply mist only during daylight hours to avoid excessive
humidity at night, which encourages disease. Remember, when the greenhouse
cools at night, the relative humidity will rise even with the misting
system off. Use a 24-hour timer to shut off the misting system 2 hours
Shading and ventilation are required during summer to
prevent a greenhouse from seriously overheating, but it is evaporative
cooling from a misting system which can actually cool the greenhouse to
a comfortable level.
When a greenhouse warms up and venting begins, essential
moisture is lost with the vented air. Plants lose moisture more rapidly
and begin to wilt. A misting system can provide needed moisture to maintain
a healthy humidity level of 50 to 70%.
Design for Cooling & Humidity Control
Use one 2 or 3 gph nozzle for every 12 to 14 sq. ft. of
greenhouse floor. Install nozzles under the benches to avoid soaking plants
on the benches. Nozzles will operate pointed in any direction - up, down,
sideways or 45° angle. Control this type of system with a humidistat.
Many foliage plants, tropicals and subtropicals can be
watered and fertilized by an overhead misting system. Use 2 gph nozzles
installed as high as possible. Control this system with a short-cycle
Maintain a higher level of humidity (60 to 70%) for healthier
plants. Protect seedlings and cuttings from fatal water stress. Imitate
orchids natural environment. Use 1 gph nozzles. Control with a short-cycle
timer: 5 to 10 seconds of mist every 15 to 30 minutes.