Ornamental and fruit trees in Alabama can take a blow from extreme weather: severe droughts, insufficient chilling periods for fruit trees in winter months, and late-spring freezes that can cause significant cold injury. By recognizing and alleviating the effects of cold injury, you can help your trees and shrubs to thrive once again.
Low-temperature injury to plants occurs at or near freezing (32 degrees F, 0 degrees C). Ice crystals form within the plant cells, rupturing those cells. Plant parts injured depends on plant species, vigor, age, hydration, and time of year. In many cases, only the most exposed part of the plant canopy is injured. In general, flower buds are more susceptible than vegetative buds to cold temperatures, although the latter may suffer misshapen leaves after expansion.
Unseasonably warm temperatures in late winter and early spring can cause many shrubs and trees to break dormancy prematurely. The sudden drop to below-freezing temperatures in spring can damage buds, flowers, and tender new growth. Trees that were beginning to flower and leaf out may experience a setback. Trees and shrubs fail to bloom, are slow to leaf out, or show damage when exposed to a late-season freeze. Species susceptible to cold injury include, but are not limited to, Bradford pear, other pear species, southern magnolia, oleander, flowering peach, hydrangea, and viburnum.
Read entire article here for more information, including symptoms of cold injury and caring for cold-injured foliage.