Unheated Greenhouses

flowerbug

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All a greenhouse does is increase the temps when the sun is up.

It has close to zero insulation, but it does help with protecting plants from wind.

If you want a greenhouse to hold heat then it needs to be partly sunk into the earth, proper insulated roof and proper double pane windows.

I have seen plans where the entire greenhouse is sunk below frost level, and I have seen other plans where you have something like infloor heating in the growing beds.

There are some creative things put there.

But for zone 4, in the winter time grow stuff indoors.

the other thing to consider is ground heat storage as you can use pipes and small fans to move heat in the winter and to get cool air in the summer. look up the youtube vids on the guy who's growing citrus up north.

for winter heating if there is any sunlight you want thermal mass capturing that heat as much as possible and if you have a way of putting up some solar hot water gatherers, some solar panels, small pumps and fans you can really capture a lot of heat that ways too. the nice thing about such a set up is that it only runs when the sun is up anyways so you don't need batteries, but if if freezes where you are at you want the system properly designed so that it either drains back to empty when the sun goes away or the whole thing is set up as a closed system and the fluids are anti-freezed - my own preference would be the first one since that can be simpler.
 

Britesea

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All a greenhouse does is increase the temps when the sun is up.

It has close to zero insulation, but it does help with protecting plants from wind.

If you want a greenhouse to hold heat then it needs to be partly sunk into the earth, proper insulated roof and proper double pane windows.

I have seen plans where the entire greenhouse is sunk below frost level, and I have seen other plans where you have something like infloor heating in the growing beds.

There are some creative things put there.

But for zone 4, in the winter time grow stuff indoors.
I think that the greenhouse does slow down the drop in temps at night, even if it doesn't completely prevent it. Typically, when I go into my greenhouse first thing at sunrise, it's about 10 degrees warmer than outside; I don't think it rose that much from the 10-15 minutes the sun was over the horizon.

I really miss my max/min thermometer from California. Somehow, it didn't make it in the moving process. It was an old fashioned one- no batteries or liquids- I believe it used the principle that some metals contract at certain temps more than others, or something like that. Anyway, I've never found one as good, and I really miss it.
 

R2elk

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I dont think the wide day-night temp fluctuation helps plants much. Mine is on patio pavers that retain some heat so it does better in late fall than early spring.
Mine is on my deck with a window to a bedroom in the house. I leave the window open during the winter. I put insulation under the greenhouse floor. I do not keep plants in it from December through February. In March I have an electric heater rigged up with a thermostat to prevent freezing temperatures.
 

tortoise

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Mine is on my deck with a window to a bedroom in the house. I leave the window open during the winter. I put insulation under the greenhouse floor. I do not keep plants in it from December through February. In March I have an electric heater rigged up with a thermostat to prevent freezing temperatures.
I want my greenhouse on the deck right against my patio door. DH says no because the gaps between the deck boards. (Isn't that why God gave us green treated plywood?!)
 

R2elk

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I want my greenhouse on the deck right against my patio door. DH says no because the gaps between the deck boards. (Isn't that why God gave us green treated plywood?!)
I insulated under the greenhouse and covered that with cheap flooring plywood. For the floor of the greenhouse, I put the same stuff over the deck 2"x4"s covering the gaps. I put a wood grain linoleum over top of the flooring plywood. No gaps to be seen now.
 

R2elk

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I insulated under the greenhouse and covered that with cheap flooring plywood. For the floor of the greenhouse, I put the same stuff over the deck 2"x4"s covering the gaps. I put a wood grain linoleum over top of the flooring plywood. No gaps to be seen now.
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tortoise

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I learned how to operate the clips that hold my greenhouse panels onto the frame. 💪 Before today I've been dependent on DH or DS14 to do it for me.

I bought a wireless indoor/outdoor thermometer with a 24 hour hi/lo. Its not a smart device, I will need to track greenhouse temps versus outdoor temps on paper. That's okay, it will help me become more aware of patterns and how I can manage my greenhouse better.
 

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