A YT channel said that when the sun was out their little greenhouse got to 105 degrees F when it was near freezing outside. It was not some little mini thing. Maybe 12 x 20 feet or so.
Is that a realistic temperature difference for a greenhouse?
It depends on the greenhouse. If it has thermostat-controlled heat elements, misters, fans, and vents – then probably not.
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Mine doesn’t get to 100s when its 32 out, but it will get close to the 90s. If its sunny and warmer, it will easy hit 105-110. You just open the door and spray with water.
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That’s a bit extreme. But it depends on a lot of things including where one takes the temperature reading inside the GH. Mine was 16ft tall and on just the right day I have no doubt it would reach 100F at the peak when it was 32 and sunny outside. Maybe even 120. At the same time air temperature might be 90 at 8ft and 70-80 near the ground.
My sunroom used to hit 120 near the peak when it was 60 outside, a 60F differential. So 70F isn’t unreasonable.
On that same 32F day if I ran the exhaust fans all out, two air exchange per minute, and the wet wall, I could probably hold 45-50F inside at 6ft height.
My highest meassured temperature hit 132F My citrus trees wilted but also grew well. It was about 55 outside.
If you don’t have any sort of exhaust/cooling it will absolutely go over 100 degrees on a sunny day, then drop to below freezing as soon as sun is going down without something to store that heat(even then it drops pretty fast)
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Last week in mine (10x14). The temp gauge is on the floor. I open vents every day and ordered some automatic temp controlled vents so i don’t have to babysit it so much. Warm days (say 60F+) i just leave the door open all day–it still stays very warm in there even with everything open on a sunny spring day as you can see.
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