Hot green house

I was planning on using my green house to try my first grow. Thinking about using 25 Gallon Plant Grow Bags with Fox Farm happy frog soils. I bought some Super Skunk seeds and plan on getting started in late April after the last freeze date
What I’m wondering is if the temperature swings will be too much for the girls? 60’s at night and up to 100 in the day.
I have exhaust fans on one end to remove the hottest air at the top and screens at the other end to let in air but it will still get pretty hot here in Montana July, August.
See any problems with my plan?


I’m an Oregon outdoor grower for many years. I personally love big holes in the ground filled with fox farms Ocean Forest. Although I think 25 G. bags would be ok, they won’t reach huge growth potential as when in ground. I like to start them indoors under T-5’s in Feb so they are nice healthy 12-16" tall when its time to go into the ground in late April. 100 degrees is damn hot for sure…they thrive best in that 65-80 range but they should be OK at 100 as long as you move a ton of air. In NW Oregons latitude I like a plant that will finish in under 50 days bud time. Nice looking greenhouse…move alot of air in and out and you should be fine. I would stick one outside the greenhouse to see if they like that environment better cause if it’s 100 outside it could get way hotter inside. Get your self one of these for sure…

That is a thing of beauty :heart_eyes:
I think @Cannabian knows this stuff and hopefully can help you :thinking:

I do like the idea of planting in the ground, but the ground here is like 85% clay 15% river stone. What size holes in the ground would I need to keep them happy? And when the roots hit the clay would that bring end to the taste in the plants?

My soil is similar as I live on a river bottom…I dug my holes about 30" in circumference and about 20" deep…my plants LOVE those holes filled with FF ocean forest…i’m sure happy frog is great too. The bottom of my holes are hard clay and rock. No bad taste whatsoever

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Just be sure you space the holes apart cause those babies can spread out. Do some research on super cropping/bending…it is extremely effective if you want bushy girls…

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Ok heres my take on it… a greenhouse for cannabis should have a roll up or removable top. The fan thing may work, clearly larger greenhouses use them. However, they have high ceiling heights. The heat can rise. A 100 degree day is brutal in a greenhouse. I would contemplate removing the chloroplast if this season gets too hot for your plants in there. Get some good quality woven greenhouse poly. If you want to do blackout you can buy black poly too.
I get mine fro. Northern greenhouse supply… great prices and fast delivery. Although I do live in Canada, there may be a retailer nearer to you.
Here is an example of my greenhouse. This house has no electric fan and 2 foot high opening for venting all the way across the top at 12 feet high. Even still the poly needs to be lifted in the summer as the temps can get extreme.

As you can see passive cooling seems to work best for me. Good luck and have fun


Thank you for the info, I will look into removing some of the top / side of the green house. I love the pictures

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You really want the best ventilation possible in the hot months. Heat slows transpiration as the stomata close to preserve water. This, in turn, slows growth. I try to keep the cover over the plants to keep rain off though.