Last night, it was -9 and this morning I went inside the greenhouse only to find my back-up heater wouldn't go on. It dropped to about 50ºF inside instead of the 55º it's supposed to be. My mechanical guy came out pretty quickly, and as soon as he took the cover off, it started up. He fussed with it awhile and took some readings and will call the factory tomorrow to see what is up with it. I'm going out later this evening to check on things -- and to take out an electric heater, just in case. But it worked fine the rest of today, so I'm keeping my fingers crossed.
My greenhouse door was slightly frozen -- I had to really tug on it to open it. And there was frost inside around the bottoms of most of the windows.
I do not like these temperatures! It's supposed to be similarly cold tonight.
Thanks for asking, Ross.