I have an 8' x 12' 6mm polycarbonate greenhouse. I'd like to find a way to cool it in the summer, as I'm in Atlanta, and summers are brutal. My greenhouse has two automatic roof vents and an exhaust fan, but I still recorded a high of 136 F last summer.

In my research I'm finding that evaporative coolers wouldn't work well due to the humidity and heat here. I'm looking at putting in a mini-split air conditioner/heating system. The cost is not much of an issue, as between the greenhouse and the garden house that I built, I already have the world's most expensive tomatoes!

I've been told that putting a mini split in a greenhouse would be hard on the copper coils. Does anyone have any experience with this or have a better suggestion for me?

Thanks!

Did you already have sun shading over the roof and west side? It can be inside or outside. I use aluminet. We had triple digit days but the highest temp I recorded in my greenhouse was 103f. I also used an improvised screen door to let more air through it without letting in the critters.

The greenhouse supposedly has shaded polycarb roof panels already.....I think adding a screen door is a great idea to get more ventilation, will look into that. Still would like to find something other than an evaporative cooler for cooling.

I've noticed that using misters, or just spraying down the floor on really hot days can cool it up to 5 to 10 degrees. I can't use misters because my hard well water turns all my plants white with mineral deposits, but I do spray the paver floors.

I'm sure you can find a small AC unit, or even a heat/cool one, but it sure would be expensive to run....but what's a bit more when it's already a big money pit? I've found we'll do about anything to have happy plants!

No doubt in the South greenhouses become hot houses. I have one plant in there 24/7 , a pothos. It is old with long vines. I feel sorry for it and may eventually take it outside in the summer months. It gets so hot in there I dread using the potting bench inside. I do have a portable a/c unit in there i rolled in 3 years ago for when I get really serious about repotting. In the end, I only get serious about potting in early spring and fall. Whew! HOT!

There are some really good photos here. someone from FL (name?) erected amazing looking shade clothes. And on Pintrest of sun sails that block the summer sun and can be taken down for winter. I think that is just about all you can do?

https://image.made-in-china.co...

http://backyardgreenhouses.com...

Welcome to the Forum. I have a similar greenhouse, same specs and materials. It does get very hot in my greenhouse as well! The only suggestion I can offer is water often inside, and if possible incorporate a big fan. PS. I failed at growing tomatoes in my greenhouse, they, although self-pollinating, just did not fruit. I replaced them with Roses. Never looked back! PS. Off the record, is that a "cuban" cigar? LOL.

These are all great ideas, I have lots more research to do before a decision.....

And yes, fwmosher, that is indeed a Cuban cigar!

I really can't add much more than other members have, but I wanted to welcome you to the forum @atlgirl! Now, I always thought I had the most expensive tomatoes...maybe just north of the Mason-Dixon line now that you are growing them in your greenhouse. I would be interested in what you have found about a "mini-split air conditioner/heating system". Any links? Thanks.