Ohioguy wrote:
More food for thought... Try a heated propagation frame. Might be
more useful in Ohio.

Interesting, but I'd like to stay away from active heating if I can.
However, I may very well place a dozen or more milk jugs of water in
there to help regulate the temperatures.

In my ideal cold frame setup, I'd have a 200 gallon water reservoir
buried underneath the cold frame. Then on the south side of the
building, about 5 or 6 feet above the cold frame, I'd have a network
of black tubules inside an array facing the sun, and a tiny pump to
slowly move the water through there from the reservoir during the day.
That would build up a lot of heat in the reservoir, which could help
slowly release the heat passively through the only non insulated
surface - the top of the reservoir tank. (located, conveniently, only
a few inches under the bottom of the cold frame)

However, that's probably a bit complex for my first cold frame
attempt.
Sounds interesting, if you do it this way, give us a followup on how
well it works.
I have also read that some build frames above a compost pile for the
extra heat.

--
Enjoy Life... Dan L (Garden in zone 5a Michigan)