Outdoor Greenhouse Cooling Options

It’s 60 degrees outside, but 83 inside the greenhouse with the windows open. I live in Maine and it will only get hotter so I ask, what do you fellow members think would be a good option for my 10x9x8 size greenhouse. I thought of adding a vent, but it would require me to cut a hole in the cover material. Solar power fans looked like a good idea so I wouldnt have to run cables into my greenhouse.

Under $200 suggestions please and thank you :slight_smile:


Getting solar powered fans for under $200 seems difficult. To have properly setup you’ll need charge controller, inverter, and battery. Plus a decent sized fan and panels.

If you can find large enough dc powered fan that will operate on output voltage provided by panels would kinda work. But you wouldn’t have any fan when you don’t have sun.

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I’m a big fan of geothermal air batteries; basically you bury a pipe below your frost line, and run air through it at a low velocity. It’s a lot of labor, but shouldn’t cost much at all.

Google “greenhouse air battery” for more info.


I’ve been searching the web for days for a decently priced outdoor fan of any sort that doesn’t require a wall plug in cord. I’ve just decided to run my extension cord to the greenhouse in a safer way then I have currently and get an outdoor fan.

The good ones are decently priced I’m just broke. Thank you for your comments!

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I see you have windows open but Can you make a roof panel open like a window? An opening at the highest point would allow the rising hot air to escape.

@KeystoneCops never heard of that. Time to do some research!

@AAA that was my first idea, heat rises so it makes the most sense to have a vent or fan at the top to push it out. But cutting the greenhouse cover material turned me away from that - I’m thinking of running a small fan hung at the top pointed towards a window to push it out that way.

my greenhouse I added some wood for a little bit of support, and thinking a small fan secured at the top where the middle board meets to push that collected heat at the top out of a window.

Sorry for the eye sore to anyone who watches, I’m no carpenter. lol

@KeystoneCops When I have my own property I am 100% going to do that!


home made swamp cooler works great for me. only about 50 bucks to make.


I also added muffin fans to the top of my greenhouse for exhaust and intake

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@Cali2LVOutdoor what else was involved in that?

Looks like 2 home depot buckets and some ducting lead to your greenhouse.


A fountain pump for the bottom bucket, tubing a few connectors and drip tips. Just gotta cut a hole on the bottom buckets lid and on the top buckets bottom so the water will run back down into the reservoir. It only uses around 55watts total.

Also there’s a guy on YouTube that makes one exactly like the one I did. I just modified some things because his method doesn’t wet the pad with enough water to work outside in my climate.

I am in a similar situation here in western colorado. I am considering building a swamp cooler for not too much money. The geothermal battery idea is interesting as well. Let us know what you choose to do and I will do the same.


My grow was 100 degrees around 10 this morning. Where I am at there are many hemp fields and I have to deter pollen so I put up a bugscreen along the sides. Next step is to string a hose along the top of the screen and viola it should drop the temp significantly. Thanks everyone for this awesome community! I’ll keep this thread updated.

Decided to just sew a patch at the top of both ends and added a small rotating fan that blows air though the mesh window in front. So far so good and tent stays below 100 degrees.