Yeah I wasn't planning on growing tropical plants in the row cover, but there are several crops which could continue to be harvested if conditions are mild enough. The row cover would also keep the snow off the ground. I'm thinking of experimenting with different heat sink materials and possibly seeing if a solar powered heater might be available. The beds are only 4x8 so not much room for a heat sink but also not much area that needs to be heated. From what little I've read so far, appears that water is actually a better heat sink than stone so I might go with five gallon buckets of water and maybe paint the buckets black.
Thanks for the sources. I'll check them both out and maybe look to see if they have any type of solar heat system.
