The good news is this only happen for a couple of nights each winter but when it happens you need to know what to do.
The coldest temperatures occur about daybreak even though humidity slows the temperature change. Cold air settles downward and cold winds compound temperature loss. The effects of temperature vary with plant species but dormancy makes plants less susceptible to frost damage. Actively growing foliage is very susceptible to frost damage. Common types of damage include death of dormant flower buds, dieback of overwintering broad-leaved plants, frost damage to tender shoots, flowers, and fruits.
How do I prevent frost damage?
– Place frost sensitive plants in sheltered locations (western and southern exposures tend to be the best).
– Place frost tolerant plants that may blossom too early in cold spots to prevent a premature break of dormancy.
– Keep plants well watered.
– Firm, bare, moist soil absorbs more heat and loses it more rapidly than soil that is loose, dry or covered with mulch.
– Manage your irrigation carefully keeping moisture levels constant
– Don’t overprotect: plants are more frost resistant if kept hardened to cold weather
– Cover plants with cloth, paper or preferably frost cloth (Home Depot or Lowes) to insulate. You can also use sheets or blankets for minimal protection
– A properly applied frost cloth can protect plants down to 30 degrees (possibly 20 degrees!)
– Completely drape the plant from top all the way to the ground. Do not allow any openings for warmth to escape (will trap heat) DO NOT gather the drape around the trunk. Remove the coverings every morning when the temperature covering warms to 50 degrees.