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Winterizing Harbor Freight 6x8 Greenhouse

  • Thread starter Raistlarn
  • Start date
I live in zone 9a so my winters get to 20°F for a few days at a time, but it usually stays ~30°F for multiple days at a time. If I'm lucky it will warm up to 50°F. I'm thinking of buying a 6x8 greenhouse from harbor freight, because my highland Nepenthes collection is getting out of hand. I believe the greenhouse uses double wall polycarbonate panels. So what I want to do is winterize it so I don't have to spend a fortune in gas/electricity to heat it over the winter. If anything I want most if not all the heat to be provided by the sun.

So I had a few things I was wondering about. I heard some people use bubble wrap as insulation. Does multiple layers offer more insulation than a single layer? Could I also combine mylar emergency blankets with multiple layers of bubble wrap to provide even more insulation?

I plan to keep highland Nepenthes, Heliamphora, Brocchiana, and any other carnivorous plants that would survive highland conditions.
 
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Hi Raistlarn, I live in zone 9b and have also been doing a lot of greenhouse researching recently. The Harbor Freight kit greenhouses tend to come with "mixed reviews" (putting it lightly) because without extra support and a nice foundation they're on the flimsy side thanks to the thin aluminum frame; it's a good thing we don't have snow here. Others have recommended buying more clips to better secure the panels to the frame as well since the kit comes with the bare minimum number of clips.

In terms of keeping the greenhouse warm over the winter, bubble wrap seems to be among the most popular choices for DIY insulation, and I'd imagine multiple layers would increase the efficacy but I'll defer to those who have a greenhouse. Strategic placement should also help (like running the greenhouse's top ridge in an east-west direction to maximize the light, and having a sheltered north wall). Other ideas I've heard include keeping large water tanks inside the greenhouse to regulate the temperature (as long as they heat up during the day); I've heard that using pavers for flooring instead of gravel accomplishes the same sort of effect but I imagine not to a great extent. Lining the door with weather-proofing strips should also keep some heat in overnight, as the door tends not to fit snugly alone.

Out of curiosity, what are your plans for summer cooling?
 
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I was thinking shade cloth as a first line of cooling, followed by automatic vents. In the worst case scenario I will hook a window AC up to a thermostat.
 
I would advise against the HF Greenhouse. It's cheap, but most reviews say you spend more time and $ after. I didn't want to deal with that, so I picked up a Palram green house with double doors and two roof vents. It has since survived 3 hurricanes!

In the warmer months I use extra shade cloth and keep doors and vents open with two small metal fans. I grow mostly lowland neps in here with my intermediates on my front porch. Once it cools down everything goes back in. I have one heater, and if temps get into the 20's, the greenhouse is usually 40+. Inside from about 4' from the base I have the reflective bubble wrap stuff, this helps insulate and reflect light.

In winter of a colder climate I would buy some transparent bubble wrap and encase the outside except for the door, and remove when it warms up.

Hope this helps!
 
Thank you. I think I would be better served re-walling, and repainting my downstairs room and using that for my Highland Nepenthes.
 
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