At a given temperature, flower buds may die, whereas leaf buds remain unharmed. Container-grown ornamentals and plants that are not normally hardy at your nursery must be protected during the winter. Container-grown plants or plants that are not fully dormant need more protection than is indicated by a plant hardiness zone map. The USDA plant hardiness zone map depicts the average annual minimum temperature for North Carolina. Frost Burn Damage can occur when frost forms on the leaves of evergreen plants such as hemlock, mountain laurel, azaleas, rhododendrons, camellias, osmanthus, and others.
Foliage usually turns bright yellow in a few days because of chlorophyll degradation.
There is no long-term damage from freeze bum. Once nominal growing conditions resume in the spring, leaves will return to a normal green color. When plants lose moisture through leaves more rapidly than the moisture can be taken up by the roots, permanent damage can occur. On broadleaved evergreens, this moisture loss results in curled leaves with dead brown tips or edges. On boxwood and conifers, foliage may turn bronze before leaf tips turn brown or black.