Fabric row covers are keeping the lettuce just warm enough to save them from freezing. This morning we had a hard frost, but there 'neath the covers, were brilliant green greens. Tonight's salad was harvested minutes before dinner. Lovely Amish lettuce on the menu with locally grown sweet potatoes.
I have read row covers can add up to 10 degrees in warmth. With ambient daytime temps near 60, the covers make cozy growing spaces! Neatly held down, the low tunnels I have made make snug mini-greenhouses for our lettuce and broccoli beds. Turnips and kale can take whatever Mother Nature dishes out and are doing just fine. I am a happy winter gardener today.