How warm will it stay? Or how much would it cost?

I am wondering if it is possible to have a greenhouse in my region Zone 8, Pacific Northwest stay above 40F for the whole winter. Or, if I were to want to keep a green house, what would I need to do to keep it that warm?

You may want to check out heaters that are designed specifically for greenhouses or houseboats. You want to make sure it can handle the humidity or a splash of water.

Here's a great site that will help you determine the heater size for your greenhouse.

http://www.littlegreenhouse.com/heat-calc.shtml

This message was edited Oct 13, 2009 6:20 AM

You will need a heater to keep it over 40--I'm in a slightly warmer zone than you, but even here we get enough chilly nights that if you want it always above 40 you need a heater. Here's the heater I use--it works fine to keep my 5x9 greenhouse in the 50-55 temperature range so if your GH is a similar size it shouldn't have any trouble keeping it at 40. http://www.charleysgreenhouse.com/4045-Portable-Heater.htm

Thank you both. This really clarifies the issue. The calculator is especially nice, as this is just looking at the possibility of getting one if I can afford it.

One method I saw used years ago was to use black painted 55 gallon drums of water along the north wall of the greenhouse which was built against the south wall of a barn. It was warm in that greenhouse night and day.

ecrane -- how painful is that heater for you on your electric bill, if you don't mind me asking?


This message was edited Oct 17, 2009 8:17 AM

Unfortunately I really don't know--I've had the GH the whole time I've lived in this house so I don't know what the bills would have been without it, and there are enough differences between this house and my old one that I can't say that the more expensive electric bills here are due to the GH heater (I suspect other things like being in a slightly colder area, being more exposed to the wind, larger house, and keeping the hot tub hot are probably bigger culprits).

I have a hot tub too, and even thought about thinking of a way to channel some of that heat into the GH instead of a heater. Let's face it, I'm not in it daily, but we keep it warm, so why not have a small hose or something to carry some of that heat into the GH? Any thoughts on that? Would it be too warm/moist?

I used a small electric heater along with the water barrels last late winter, and had barely a blip in our electric bill, in an 8x8 Rion. Since then we have caulked it better and I added insulated panels on the North side. I expect it to be even cheaper this year unless we have too many cloudy days when the water doesn't get heated.

aww gee, who had to go and post that link about heating costs, makes me re-think everything...again. lol ;-)

FYI, I found a similar heater to what ecrane posted above when I was at Lowes yesterday for $19.99. Might be worth checking out if you're looking for something. I picked one up to have on hand. I figure we could use it in the other shed as well if needed.

Ace hardware carries that heater, too, about $25.

I just put mine in the GH, as the temps tonight are dipping into the high 30s, and there is a frost warning in effect. I like how it has a thermostat, so I can set it on the lowest setting, and it automatically shuts off when it gets to that temp. I wish it reflected the temp in degrees rather than low --> high but beggars (with beer budgets) can't be choosy.