"In trying to decide whether now is a good time to pull covers, or not, I always begin by thinking about the "crop stage" and how hardy the plants may be in mid-December.
Unlike last year, we have not had as much good hardening weather, and so I believe the idea of delaying the cover application has been justified. Right now, I think uncovered Chandler plants could handle cold temperatures in the upper teens, but mid-teens and lower would make me nervous.
In looking ahead into next week, I see that areas of the Piedmont like Gibsonville, NC (near Burlington) could experience a minimum of 18 F on Wed morning (12/23), whereas at Clayton (southeast of Raleigh) we will reach a minimum of 20 F. Leading up to Wednesday we will have a series of what I consider ideal hardening off temperatures (40's in day, 20's in night). It is best to allow the plants to be fully exposed to these kinds of outdoor air temperatures before pulling the winter blanket. In the milder Clayton area, we will not pull covers at all this winter unless there is a severe freeze threat, and a forecast in the low teens or single digits will tell us to go ahead and cover. We will then leave the covers in place through January, provided that we do not encounter a week of abnormally mild temperatures. The row covers can really elevate temperatures during the day, and if the forecast is for a week with daytime highs in the 60s we will pull the covers to the side.