If freezing rain is in the forecast, you can use a piece of plastic as a second covering, but do not let the plastic come in contact with foliage or flowers. Alyssum, calendula, cyclamen, pansies and stock can survive a mid-20 dip without cover, but prefer protection when the thermometer drops lower. Cover or wrap shrubs subject to freeze damage. A hard freeze will damage the blooms on azaleas flowering this time of year. Use plastic nursery pots to cover plants.
Large boxes serve the same purpose.
The winds that accompany cold fronts have damaging drying effects. You can remove mushy stems such as those on impatiens and begonias, but don't prune woody plants such as hibiscus, oleanders, hydrangeas or azaleas. Wait until March when there's no danger of a freeze. The damaged wood will protect green, live wood farther down the branches. Water the plants every two weeks if there is no rain.