I'm planning to put up a small greenhouse this winter, myself. Mine will use one of those collapsible metal awning frames -- you know, the kind you carry around for picnics and such, that make a 10 x 10 shaded space. I've been considering whether to use thick clear plastic sheeting for the sides, or the corrugated fiberglass that is often used for such things. The consensus of the guys at the UT gardens is that I should use the plastic sheeting -- it's cheaper, and pretty durable. If you use it, just be sure to get REALLY THICK sheeting. I think Lowes or HD sells it in 6 mil thickness, which should work well.

As for heating -- I'm still debating whether to heat mine or not. If I do, I'll probably use a small space heater and a weather-proof extension cord!

Please talk to someone in the know about heating your GH. Extension cords and electric heaters can be a very dangerous thing. Not only does it need to be weather proof, you must also use a gauge that is designed for this kind of use and this is where I get lost.
I live in zone 7 in NE MS and use heat bulbs in my GH. I only use them when the temp falls down into the low 20's. This allows me to keep tender perennials from freezing, but not tropicals. I also start many seeds in the gh and have good luck growing them. Of course, they don't really start growing until about March when it starts to get warmer. I've also kept cutting in 3 gallon buckets all winter and they didn't freeze(Confederate roses and Brugs). I had a tropical Hibiscus that died, totally died! and one that froze the stems off, but the roots stayed alive enough for it to regrow this year, but it did not bloom. This will go into the house this year.

I had problems last year with white flies and aphids. I did a total cleaning this Spring,moved everything outside, used soap and water on aphids and some spray for white flies. When I put everything back into the greenhouse, I added a fan to keep the air moving and haven't had any pests so far. I plan to continue using the fan, even this winter. I sure hope this helps with the pests.
I hope you can see the two pictures below. The first one show my lean-to GH on the back of my shed. The next shows a portion of the inside. Mine is 10x20.

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Thank you for the ideas. I believe mine is a 6x20....not sure. Hubby will be home next week so we will try and get it covered. I see the cups would be better for me to start seeds with than the egg cartons. LOL Plus, using my daughter's blinds that I am taking down to use for lableing....

If you want a good strong cover for the roof, check out
Bob's Tough Plastic, can order on the internet. Plastic
for the sides will last a lot longer if you get U V protected plastic, got mine at Co Op store. Most expensive
item was a vent free propane heater, and exhaust fan. Wife
can't send me to the dog house, I go to the greenhouse.
Have fun, a great place to pass the time in the winter.
Norm

I traced Bob's Tough Plastic to Northern Greenhouse -- http://www.northerngreenhouse.com . Thanks for the suggestion, Norm!

Here is a link that might be useful: Northern Greenhouse

Just make sure you do have reliable heat! Several years ago I had little tomatoes, cukes, yellow squash, beets, collards, and I don't remember what else..at Thanksgiving, but my wood heater (first night to use it) went out, and everything froze. We are now installing a wood furnace, that is supposed to do the job, and we are going to try it again. Ours is a 16X40. In the process of cleaning it out, and setting it back up. Goats got in there and tore up everything, so we are starting from scratch again. Lets all keep in touch.

I set up the canopy frame for mine this afternoon. It'll be tiny compared to most -- just 10 x 10 -- but a lot better than nothing! I'm on my way to Lowes to check out plastic prices right now.

I got a catalog today from Charley's Greenhouse and Garden. Have no idea why they sent it to me, but they have a lot of stuff in it that would be useful for greehouses of all sizes and types.
I've never ordered from them, just on the mailing list.

Here is a link that might be useful: Charley's Greenhouse

I read the pdf on the Northern Greenhouse site and WOW there is some great knowledge about building greenhouses and designing them for maximum efficiency, humidity, and soil temps! Read it here

I've been wanting one big enough for my tropicals for some time now... looks like it's not that expensive or difficult to build a little one. Their woven poly sounds fantastic - it's been my experience that 4 or 6 mil clear plastic doesn't hold up for a whole season... it shreds up. So if I were to do a greenhouse this winter I'd do a tube made with rebar like Bob suggests in the pdf document.

I have not seen but one reply to the question about leaving dahlia tubers in the ground in this area. I am just north of Nashville.

Anybody??

Sorry Rita, I don't grow dahlias! I've got no clue!