I'm going to right now though. It's supposed to hit -20f here tonight (that's -28 for you celsius minded folk). It was 60f yesterday (16C). It's about -15f right now. My GH door was frozen closed earlier. I suppose that's good, because it means air isn't going to get in via the cracks. I should have added the extra triple-wall poly to the walls yesterday. It's just sitting in my kitchen. Should my 17,000BTU heater fail to keep up, I have a propane tank heater I can toss on. I just don't like the idea of the ethylene gas building up in the GH. I have lots of cool stuff in bud that I don't want to lose. It's *way* too cold right now.