sunlight for the cold frame

I pulled off the tarp covering my cold frame today and let the plants get a couple hours of sun. We are now getting 10 hours and 19 minutes of sunlight per day here in the Boston area. Theoretically enough for plants to grow. Only its too cold. Tonight's predicted low is 5*F (-15*C). Brr. The cold frame never goes much below 25*F.

Its my first year with a cold frame and I think the plants look surprisingly good. Especially the spinach. I will try to give it a few hours of sunlight daily now and see if I can get it to start growing.

It looks like I should bring out a bucket of water for the dry soil.