I grew for years above the 45 *.Depending on variety,strain I have finished oct. 11-nov.10.I always start em in march indoors.Exp. has taught me 2-3 days of frost is not a disaster.Any more than that,you can use anything from large trash bags to burlap,even a cotton sheet will work fine.Dont let frost hit them more than three days in a row.That was northern michigan,where I grow.Just cover them,the weather probably will warm up shortly.ENJOY!