How much warmer are they?

[Mudman]

Originally Posted by Jaysan

I am considering a cold frame to start seedlings in instead of indoors under lights.
If it would keep enough warmth to work starting about mid March, and it can get below freezing in mid March in southern VA, I think I could do it.

Anyone use theirs for that purpose?

I think this would definitely work for you. If it is well insulated you can easily keep it warm enough in March. I can, and I live in a much colder climate than you. And if the forecast ever looks really bad you can cover it with a blanket or add a light bulb etc.