Magnolias are the classic iconography of the southern United States with their glossy green leaves and huge white flowers. What some people may not know is that magnolias can be grown in many parts of the United States outside of the South. Southern magnolias suffer from the cold, but many cultivars can tolerate snowy winters.
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Southern magnolias (Magnolia grandiflora) are enormous evergreen magnolias, growing upward of 80 feet with a 40-foot spread. They are native trees that thrive in USDA Hardiness Zones 7a through 10a and are occasionally spotted further north in protected areas. These southern trees are very prone to damage from cold weather, especially when young.
While the iconic magnolia may be the Southern magnolia, many hardy varieties are available in North America. These magnolias, which are hardy to USDA Hardiness Zone 4, tend to be smaller trees. Deciduous magnolias have a wider range of flower colors, from white to a variety of pinks. 'Star,' 'Leonard Messel' and 'Merrill' magnolias make beautiful ornamental trees.
Magnolias suffer cold damage when winter temperatures fluctuate or unexpected frost or snow arrive late in the season. Buds tend to be damaged most severely, cold snaps can result in the death of all magnolia buds for that season. If foliage begins pushing out from behind damaged buds, it can be assumed that there will be no further blooms that year. Vegetative buds can also suffer frostbite from cold exposure but they are significantly more resistant than flower buds.
Cold-Damaged Magnolia Care
It's best to wait until spring to assess any freeze or frost damage on a magnolia. Remove any obviously dead limbs and branches. Allow small cracks in bark to heal naturally and treat larger cracks with copper solution to prevent diseases. Fertilize the damaged tree lightly and mulch it deeply to help prevent further stress while it is recovering.