Ok so I plan on building this lean-to on the south side of my house. It will be 4'x6', I know pretty small, but the main use will be for my citrus trees. I do plant tomatoes so possible for them as well. I can only afford 6 mil plastic for the walls, but I intend to put it on the inside and outside giving me a 3.5" airspace between them. The roof is going to be either shingles or most likely corrugated metal because its free and Ill possibly paint it black to help absorb heat. Im going with a solid roof because we can get hail the size of baseballs in the spring. If I need more light I guess I can install a skylight.

I know plastic isnt ideal for holding heat but I hope this will do pretty well. I plan to have a concrete paver floor, black buckets of water, plus the heat from the house, and supplemental electric heat for the coldest times. Ill work out ventilation as im building it.

any chance I can maintain 40 degrees plus. Last year we had a good week in the low teens.

Here is a link that might be useful: {{gwi:302512}}