Im zone 9, but in a real cold area, its consistantly in the low 30s Dec, Jan. My cool season crops just wait it out until Feb and then grow. This year they got further along cus Fall was mild, but still they wait now for spring. It still warms up into the 60s or 70s (or hotter)in the day. I have tried the light floating row covers, but that didnt do a thing, maybe if I secured it to the ground, but they werent big enough.
Im thinking about using the heavier row cover, the ones that let in 50% light. And building a hoop house to secure the fabric on all sides, and hold in the warmth. Is 50% light good enough? It is nice and sunny here most of the winter. I dont want to use plastic because it would get too hot in the day. I dont want to have to open and close it to adjust the temp. Thank you for your experience!