I live in Northern Elko County, Nevada and it gets down below freezing (can be wayyyy down) I am pretty new to the area and have a greenhouse attached to the south side of my house, about 8x20 feet in size. I am trying to figure out if its going to be worth the cost, or even possible, to keep things growing in there during the winter, and how early I should try to get things going in there in the spring. its about 30 degrees today, and the temp in the greenhouse is almost 70 degrees. I do have one of those oil filled heaters..was wondering how that might work. I guess I need to track the temps in their better through the nights..but any suggestions from you would help. This is the first time I have had a greenhouse, am an avid gardener, but am new to this cold climate and could use some help. Thanks in advance.

OT. I'm in zone 7. I leave my canna's in the ground. I also have some in large pots.(see picture) I just cover the pots with a pile of leaves. I do take in the Nancy's Revenge. I leave most of my other EE's in the ground. Black Magic, Big Dipper, uprights. Even the one's in gallon pots come back but do not grow well unless I transplant them into the ground or larger pots. You know how it is. You buy stuff and it just never gets planted. I doubt they will get envasive if they die down each winter. You may have to seperate them but mine do not get out of control.

You might also want electricity for lights for working at night, and an emergency heater should the gas run out (if you're using gas heat that is). Just be careful with the electricity of course ~ water being so prevalent in a g-house and all. My electrical plug is up at the top of one end of mine, up out of the water. I have a greenhouse made of cattle panels and it's wonderful. Materials were about $600 for a 20' long one, but would be a good chunk less if you used the regular 16' cattle panels instead of the 20' ones (16' panels 9' apart gave me about 5'10" of height ~ 8' apart I think would get you 6' tall ~~ 20' ones like I have makes it about 7' tall). It's plenty sturdy enough to hang two rows of hanging baskets down each side. I built it like the one here, but used 4x4s on the bottom and closed in the ends with plywood on a wooden wall frame. Here's a not-so-good picture of it before the second layer of plastic was taken off. More pictures. I don't use automatic vents, but would like one in each end eventually. It's not been too hard to remember to open it up during the day and close it at night, but automatic is always nicer. I do have a large window in one end, aluminum framed one installed upside down so when it's open the open area is at the top. I use two layers of 6 mil plastic held apart by lengths of pvc pipe insulation to form an insulating space. Enough plastic and pvc insulation to cover my 10'x20' greenhouse costs about sixty bucks. The plastic ($40 of that sixty) only lasts one year, but the insulation lasts years. It would be about the same price or a bit more expensive (even pro-rated per year) to buy four-year greenhouse plastic, but worth the extra since you only put it on once every four years and it won't crumble to pieces come spring (those pieces are a pita to pick up if you don't get the plastic off in time). In my climate, I don't need supplemental heat in it if I'm only trying to keep things from freezing. Tomato and pepper seedlings, rooted cuttings, etc., all do fine when placed on the ground in my unheated g-house. Actually, even my tropicals do okay, though the tall ones smetimes get nipped on extra-cold nights (only a couple times a year). I'd bet I could put some floating row cover over them then and they'd still be okay. But you'd probably need extra heat. If you did two layers of plastic, you wouldn't need as much as with only one layer. One other thing I did that's handy ~ I put it under some deciduous trees so it would be shaded in summer and get sun in winter. This works out really nicely. The plastic lasts a bit longer this way and I can still use it in summer as a potting shed. These can also be used for any kind of shed. At the link, you'll see pictures of the first one I built years ago that's now being used as a chicken coop. Handy!

When I first built my greenhouse a Harbor Freight 10 x 12 I used a kersone heater even though I did not like it because of fumes to keep the Greenhouse warm during snowstorms. It worked well to keep snow from building on the roof. The next season I tried a small plug-in heater for greenhouses but it would only bring the temp up a little. The next season I insulated the inside of the greenhouse with bubble wrap half way up. Also, when I built it I insulated outside the foundation 18 in. down I put home insulation that is used for cement walls. It is pink or white sheets and cut them to any size. Last season I purchased a Solar Pool cover and put it over the whole greenhouse. I needed to cut by the doors and vents but it works great. Snow slides off no problem and the greenhouse is 15 degrees warmer. I installed a 100 lb. propane tank with a nice heater. So far the insulation works so good that I had the heater on only with the pilot light on and even with that little heat it kept it at 50 degrees. I went initially to a few seminars at UCONN to see how they kept their greenhouses warm.