If it has withstood a lot of cold already, it ought to be fine. However, if you have been having some pretty warm weather and there is a lot of really new tender growth, that part might get nipped back a little. I usually throw a floating row cover over my lettuce anytime I think it likely that we'll drop below about 20-22 degrees. With row cover, my winter lettuce survived temperatures in the 9-11 degree range back in early and mid-winter. Without row coverage, it showed a small amount of damage at 22 degrees. If you don't have floating row cover, a bedsheet or lightweight blanket would work about as well. Our forecast for last night was 29 degrees but I thought it would be colder and covered up everything with floating row cover. Glad I did as we went down to 21 degrees. The only thing in the garden that froze was the taller asparagus spears. Oh, and the fruit trees will lose their fruit but I expected that too.

Even when lettuce here gets nipped back by extremely cold temperatures it usually puts out new growth almost right away.

DH went out yesterday and covered the peas, cabbage, radicchio and cauliflower transplants with leaves. Nothing else is up. We were at 24F at 7AM. It is supposed to be as cold or a bit colder tonight so hope everyone can save whatever they've put out.

I have not protected any of my cole crops this year, but I did learn a valuable lesson in harden off, and re- hardening off. The plants I planted earlier are doing ok. The ones I brought back into the house and planted after the cold spell we had a week or so ago are in bad shape. I planted them just in time to catch a few days in the 70's and then 4 hard frost without hardening them off again. Even though they were only in the house a few days, the shock of the weather extremes seems to have killed most of them.