dave i just use auto openers and cheap clearence fans,cheap heaters,and cheap gutter cables.i did put a line of misters down the ridges and it works great when it warm and sunny but i need to adjust them better.extra clips are the way to go.this fall i will do some alterations to make it cheaper to heat. i will take out the poly from the roof and walls on the north side and double them on the south side with an trapped air space like a thermal window.and insulate the north wall as much as i can.i also want to insulate the floor better.maybe one of those clearence blue flame heaters will see.oh yeah the doors are a pain i might put hinges.i will post pictures when i do it. heres a tip dont buy anything unless your sure you need it like an automated super duper fan with shutters if your just starting plants and extending your season or build any thing that cant be moved quickly out of the house its very small and you will probaly want to move things around depending on the season.good luck. rob

I suspect that you won't get a lot more growth season, though it depends on what you are growing (e.g., cold season crops vs. tomatoes). I just used a greenhouse heating calculator to get a rough idea of what you can expect as far as heating requirements, and it looks like, if it is zero outside, the heater going at full blast will keep the inside at about 35F. Obviously, when it is warmer outside, it will be roughly that much warmer inside the greenhouse, but do you really want to be using a huge amount of energy to keep the greenhouse at a temperature that will allow you to actively grow? I live in a much milder climate than you, and I also use a 1500W space heater, but my goal is to protect sensitive plants, not to try to grow tomatoes that will cost me $20 apiece due to energy costs. I'm not trying to discourage you...just sharing my experience: I had high hopes my first winter until I realized what was practical and affordable.

My HFGH 10x12 has been up for three years. For me, it's been a great way to try greenhousing without investing tons of money. However, I don't recommend building it without reinforcements to help prevent panel loss in wind (there are some sad stories in this forum about what happens without reinforcements.) Many forum members have shared inexpensive HFGH reinforcement tips, and I've gathered some of those ideas in my blog below. Our GH withstands heavy winds routinely with no problems. Building our Harbor Freight 10x12 Greenhouse Some HFGH owners find the Chinese-manufactured twinwall polycarbonate panels deteriorate prematurely (HF offers no warranty.) This seems to happen more often in sunny southern locations. Some HFGH owners in this forum don't have this problem, and shadecloth use seems to help. My panels developed obvious yellowing about two years out, and will need to be replaced next spring. Panels unprotected by shade cloth have developed 1/8" to 1/4" size holes on the outer poly wall (4 to 10 holes per wall panel, I just patched them yesterday.) Structurally the GH is great, so I'll purchase 4mm twinwall polycarbonate or 3.5mm Solexx panels elsewhere to replace the failing HF panels. Replacing all panels will cost about as much as the initial GH kit itself three years ago, but other manufactured kits of the same size are still a lot more expensive, so I don't regret the purchase at all. This website's heating calculator lists the various heat loss values for a range of greenhouse covering materials, so you can compare them. (The Harbor Freight twinwall polycarbonate panels are 4mm thick.): Greenhouse Heater Size Calculator Hope this helps a bit.

Hello BearBryant (Roll Tide!) I haven't come across anyone yet with reports of how the Krylon spray product might work. I met one person who planned to use it over a year ago, but when I contacted him for an update, he said his build had been delayed. Since this thread, another HFGH owner posted to the thread linked below. Rtyu said he'd applied the Top Secret TS-100 coating mentoned above, three years ago, and was still very pleased to see no deterioration. You will find his posts close to the end of this thread: HFGH Polycarbonate Panels Failing, Part 2 Between the two products, I'd probably bank more on the Top Secret coating, because it's roller applied, and that will likely allow a thicker and more consistent protective coating than the Krylon spray product. Just a guess on my part, though.