I have a minimum of two fans running in each greenhouse. During late summer/early spring, before moving everything in the greenhouses outside, I have three fans running. One is at the floor level in each greenhouse and it runs 24/7. The other one/two, are on timers that are set to run 8-12 hrs., depending on time of year. I have posted numerous times about the importance of air movement (and why I think I have so little pest/disease problems), but the majority of those were on the "Orchids" forum.
