Hey all! I am in the process of pouring an 8×8 concrete foundation for a greenhouse. I live in the PNW, and want to be able to keep some dwarf citrus as well as do starts. I have chosen a metal frame greenhouse kit because of the 10mm thick polycarb (Palram Canopia Glory greenhouse) but my friend just told me that this won’t work because the metal frame won’t retain heat and therefore won’t keep the plants warm in the winter. Supposedly I need a wood frame greenhouse to do that. But the wood frame greenhouse kits I have found have much thinner polycarbonate walls. I did find the Outdoor Living Today 8×8 Cedar greenhouse that has 6mm thick polycarb. Does anyone have experience with either of these kits and which one might serve my purposes better? And if there is a better one I should consider? I really don’t have the money to go super expensive. So under $5k is required.
by awayfromtheexplosion
3 Comments
I am also in the PNW and we just finished the Palram Harmony 6×10 with a wood frame base, each corner has a concrete footer 4’ underground and 4” deep pea gravel inside for drainage. Over winter I was expecting to use a small greenhouse heater with thermostat.
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I have not built my greenhouse yet, because I need a backyard to do that, but from everything I’ve read, all greenhouses need supplemental heating during winter IF you want to keep plants thriving year round.
From a material perspective, wood is better than metal during the winter. The thickness of the polycarbonate panels is not as important as their structure (double-wall) and their installation (are they insulated against drafts/air?).
When people argue about the frame materials, they are arguing about how much heat the greenhouse can retain on its own **in order to extend the growing season** and then take a break during winter. All of these greenhouses heat up during the day and then lose most of the heat at night. Most consumer greenhouses are meant to stretch out the growing season, not to nurture plants year-round.
But if you want to keep plants like citrus in your greenhouse and you want it to be functional during the winter (by never allowing the temperature to drop below 45°F) then you will need a heater regardless.
So I would choose whichever greenhouse is slightly below your budget and then shop around for temperature-controlled heaters, where they kick in when the temperature drops below a certain point.
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I’d go with a wood one. After assembling this aluminum one I had to reinforce it for winter and for what I spent it would have been cheaper and faster to build one and order 4×8 polycarbonate sheets.