Novice greenhouse gardeners learn the hard way… that a hot greenhouse (regularly above 90 degrees), reduces vegetable crop production. Be sure you have adequate ventilation and always have your fans exhaust out, rather than blow in. You can also add shading fabric to reduce heat, but don’t over shade your greenhouse or plants won’t thrive. For glass and polycarbonate covered greenhouses look into “shade paint” made for greenhouses- which is sprayed on the outside of the glass. The paint sluffs off the greenhouse in colder weather.
Growing Home - Cooling your Greenhouse
