Winter heating

Last night was the coldest we’ve had this year, and it tripped my greenhouse temperature alarm. I run about 5000 BTU/h of electric heat in the geodesic greenhouse during the winter. Together with about 2000 BTU/h added to the water tanks, that suffices for most nights and all but the coldest days in our climate. This year I had to strip away the inner plastic lining because it was deteriorating, which has left me with less insulation that normal, so I expect to be using supplemental heating more. Not the most economical way to run it, I’m afraid, but sometimes I don’t have a choice.

I haven’t set up the water heating yet this year, and that is hurting things as well. So last night I fired up the supplemental propane heater. It’s capable of 18,000 BTU/h in three segments, and each segment adds about ~10F differential to the temperature inside the greenhouse versus outside, normally. With less insulation this year I expect it to be less effective, but still hoping it can pull me through our coldest nights. I checked all of the fuel line connections and the venting and fired up each segment for a good, long burn to make sure they burned safely and completely after its long time shutdown since last winter.

Unlike the electric, which is all thermostatically controlled, the supplemental heating is all manual. And that suits me fine. I’m a pessimist when it comes to automated systems. I expect water pumps to clog and cut out, fans to die, and auto shutoff mechanisms to fail. And I don’t trust the propane completely in a location with no one present to monitor it, so I feel better when I have complete control over it. I’d rather forget to handle something and have the greenhouse freeze over, than have it burn down because I wasn’t forced to go out there every time it turned on, off, or fired up another burner.

After the test I walked around inside a bit. The Angel’s Trumpets are still blooming like crazy. Fuschias and some runaway nasturtiums add dashes of bright color here and there. I’ve overwintered the habanero family peppers (heatless, full heat, and ghost chiles) to see how they do through the winter and how they perform in their second year. Everywhere the greenhouse is crammed full of plants, arranged for maximum light exposure while still allowing air circulation and access for watering. It’s a bit of a mess, really, arranged for plants rather than people. And I love it.

Geodesic Greenhouse

Geodesic dome greenhouseAt some point in the future I’ll probably add more information about it on this website, but for now the construction details on my primary greenhouse are hosted at

It is a 20-22′ (depending how and where you measure it) 3 frequency geodesic dome built with cedar and glazed with heavy duty woven poly plastic. The construction was very rewarding, and after having it for several years I’m sold on the design for greenhouses in our climate. It will show up throughout my future posts.