A coldframe will be going between the side walk and the house. I want to put it below ground (at least a good part of it). Treated lumber is probably the best bet. But what about growing vegetables it it? Are there any other materials that wouldn't be toxic, but still hold up with the wetness?
Aw shucks...flattery will get you everywhere!
I've used sliding glass doors for coldframes. They are of a good size, usually thick glass (and often double-paned). They are HEAVY tho so the last time I used one I stuck a cedar post in the ground behind the cold frame, put a pulley at the top of it, and tied a cable to the front of the glass door then up thru the pulley and down the back side of the post. At the end of the cable I attached a weight (I used an old plow but you could use a cinder block or whatever). The weight became a ballast and all of a sudden you could lift open the 50# glass door with only one finger. Worked great!
If there was a drawback to it tho that would be that a strong wind could also open the lid but I remedied that by using a screen door latch to keep the lid closed when I wanted it to stay closed.
I'm planning to put in a couple of smaller cold frames this fall. I've constructed two before this, but in North Carolina. Now that I'm in New England (well, 5 miles away in NY), I have some questions.
Is there an optimal slope to the lids to take in the most sun at this latitude? And how deep should I go into the ground? Don't know how deep the soil freezes here in Z.5b, but I know that I mistook it for concrete my first spring!
Julie...I remember reading some yrs back that the slope isn't all that important unless you are living in upper Alaska/North Pole area (where the sun would be "extremely" low on the horizon).
Some folks make their cold frame lids straight across, however I'd recommend at least a good enough slope that the rains and melting snow will run off.
The last ones I made the back side was 6 inches or more higher than the front side, all were facing due South.
Depending on what you're gonna put in there will also depend on the depth of the walls (or height).
You can find your freeze line from either your local ag agent or call a plumber (they have to install water lines below the freeze line). However, a cold frame doesn't necessarily need to be below the freeze line because the glass on it will keep the insides warm (by allowing the sun to shine in).