Greenhouse resources
Laurie,
A lot of people make greenhouses on a tight budget and most wouldn't hold any amount of snow. If you are seriously considering building a greenhouse at some point, then you should consider something of this quality (
http://www.hartley-greenhouses.com/) and just have some of the panels replaced with Solacryl. You wouldn't be able to tell the difference because it looks like glass.
During the darker months, you can use UVB lighting in shop lights. ...
...
Laurie, having a greenhouse in the extremes of Montana presents some serious challenges; I would definitely get a greenhouse from a manufacturer in a climate like yours. For your situation, I don't think I would trust any British g.h. mfg. (nothing political here, just practical). But if your house belongs in Architectural Digest...
In college, I remember there was a lot of wind and snow testing information out of the Colorado program (I believe it was CSU), before the industry collapsed due to imports. You might search for their publications at a library.
This company in Colorado looks good: CSI Hobby Greenhouses :
http://www.myhobbygreenhouse.com
Then there's Shane Smith, who is in Wyoming, and has a couple of great books:
http://www.greenhousegarden.com/
The Rough Bros. engineer a lot of houses for universities and public gardens. If I won the lottery I'd have them build my dream greenhouse...
http://www.roughbros.com/index.html;jsessionid=76BDA2EFCE2E4E94F7588449E709E6C6#
A little more realistic, are the ones from AgraTech:
http://www.agra-tech.com/menu.php There are a lot of businesses here in the Bay Area that have their houses and we have some real wind here (no snow tho').
Oregon Valley makes a lot of super-strong structures for commercial growers:
http://www.ovg.com/
A bunch of pre-fab types can be found at
http://www.greenhousecatalog.com/ and at
http://www.farmtek.com/farm/supplies/home
For general supplies, books and ideas, (but not the best prices) there's Charlie's:
http://www.charleysgreenhouse.com/
Also see Lee Valley for all sorts of supplies:
http://www.leevalley.com/us/
Back to securing your g.h. against the elements: You will want to consider an anchoring system of cables and buried tie-downs. We used these in the mountains of Oregon, and there they saved the greenhouse more than once.
You might also contemplate a hybrid wood/gas furnace that would still operate in a prolonged power outage. Having lots of automatic electronicly-controlled cooling and heating makes things safer and easier. They all cost small mountains of money. I know.
