Tree and shrubs whose leaves and flowers have been burnt by the freeze will recover. According to Dr Bill Fountain, our UK Extension Specialist, woody plants will leaf out again. It may take a couple of months to really understand the extent of the damage to our plants but they will most likely not die.
Do NOT fertilize trees and shrubs now. Keep woody plants as un-stressed out as possible during this growing season. This means watering when we have a dry spell. After a couple months, freeze damaged trees and shrubs can be aesthetically pruned -- meaning, get rid of the ugly, dead stuff. I want to emphasize that we should still practice good pruning practices.
The bark of the crape myrtle (and our beautyberry) here at the office cracked and sloughed off with the cold temperatures. Crape myrtles are marginal here in Zone 6, so there may be a lot of dead limbs on your plant this year. Again, you'll have to wait to see what resprouts and at that point, make pruning cuts.
For Dr Fountain's entire opinion on this, click here.
Herbaceous perennials were hard hit as well. Check out our hostas here at the office.
For these plants, you will have to wait a good week to know exactly what is dead and what's alive. At that point, you might want to remove the dead leaves. Anything that remains green, I would keep since it will be photosynthesizing and making energy for the plant.
Good luck. Let me know how your plants recover from this historic freeze.