Solar Heating Greenhouse

Solar Heating the Greenhouse

It is amazing how effective solar heating the greenhouse is.   Out Pit Garden awoke this morning under the tarp at a heat maintained 50 degrees.  The temps were well below zero, but by 10AM, with our insulated tarp off, they started rising.  By noon it was 70 degrees and at the peak of the day you can see in the image above we hit 82 degrees!

This not only is great for the plants during the day, but we’re able to store this energy in our trash can heat sync and cement walls, requiring much less energy to keep the temp above 50 degrees tonight.   With the sun so low on the horizon our good solar heat exposure is from about 11AM till 3PM each day.  It is usable about one extra hour on each side so we get about 6 hours of solar heating.

That heat seems to take about 6-8 hours to bring the temp of the greenhouse back down to 50 degrees.   If we didn’t have starts currently going, something that we’ll almost never do this time of year, I’d let the earthen walls and heat sync do their job.  This year though, due to our late start, that remaining 8-10 hours we’re using propane and electric heat to keep it warm.

Andrew Blessing

Check out our post on automation for the lights and heat in the pit garden.
Greenhouse Ventless Propane Heat


  1. James Newton Reply to James

    I wonder if you could add reflective panels on the sides to increase both the amount of heat trapped and extend the length of the “day”.

    Or add a solar water heater panel (or 12) to the side and pump the hot water into the walls or water tanks to store heat for the night.

    • Interesting idea with the solar water heater panels, I’d have to think that one through and see how difficult it would be to add. As for the reflective panels on the sides, I’ve tried that and it gives the plants some excellent additional light, but it causes the walls to retain significantly less heat. My thought has been that this tradeoff isn’t worth it at least this time of year.

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