How to make the greenhouse cool in summer?

Lena - August 1, 2022

AdviceSkills

As a novice gardener, it makes sense to know how to keep your greenhouse cooler in the summer. Perhaps some facilities can keep plants cooler.

Besides vents and fans, what better suggestions do you have?

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If your greenhouse is covered with plastic film (there is excellent quality greenhouse film available), and design allows, you can roll the walls up and tie them.  That is what we have done with our DIY hoop house.  The overhead plastic actually cuts a bit of the sun, so feels slightly cooler than in the direct sun.

 

Figure out what temperatures the plants in there like to be at and keep a thermometer in there as well so you can tell when they are about to freeze or cook.

Windows, vents, fans, or rolling up the sides like Dogpatch mentions here are good ways to adjust the temperatures. Their position in the greenhouse can also factor into things such as if they are near the door or on the other end, on the north or south side of the green house, and up closer to the roof or down near the floor. Play around and see what your plants like.

 

An older method used in glass greenhouses is to cover the glass during periods of damaging heat and intense sun. This can be done with a plastic mesh or thin lime wash on the outside of the glass that will wash off when it next rains. The lime wash has the added benefit of helping preserve any timber sections of the greenhouse roof and killing mold in any crevices. Our greenhouses have pneumatic/automatic openers in the apex of the roof which combined with opening the doors creates a convection current which will work as well as any electric fan.

Poly tunnels are great if you can have opening doors each end so you can also drive a tiller through them.

 

Lime wash – what a great idea!!!  Last year we used a powdered kaolin clay to spray our apples (pest deterrent).  It coated the trees with white powder.  We had a profound heat dome last June and the apples that were well coated suffered zero sunburn.

Our tunnel is still a work in progress.  It will have removable ends, actually one end will have a door, the other will be hinged so the top half can drop for air circulation. (we built one of these some years ago like that).  We can drive our compact tractor/tiller through it.