The southern magnolia is one of the most beautiful trees of the American South. Known by the botanical name magnolia grandiflora, it is perhaps the best-known species of the more than 100 varieties in the magnolia family. Growing within USDA plant hardiness zones 7 to 10a, the southern magnolia ranges in an arc from the Pacific Northwest, through the southern states and up the eastern seaboard as far north as Massachusetts.
Magnolia grandiflora is a very large evergreen tree, reaching heights of 60 to 80 feet when mature. With a spread of 30 to 40 feet near the base, full-grown southern magnolias are cone-shaped. The foliage is dense with shiny, deep green leaves that grow up to a foot long. The bark of the tree is quite thin and therefore easily damaged.
The large, striking flowers of the southern magnolia are its most notable feature. Growing up to 14 inches in diameter, the creamy white blooms emit a distinctive fragrance that has been compared to jasmine. Numerous bright red seeds emerge from the brown, cone-like fruit that grows in the center of the flower. The trees usually bloom from late spring through to midsummer.
The southern magnolia is a native North American species most commonly found growing along river banks and streams where water is abundant. With adequate water, magnolia grandiflora will thrive in full sun. However, in poor soil or dry areas it does best in partial shade. The trees prefer slightly acidic, well-drained soil but have some tolerance for clays and more alkaline conditions.
Southern magnolia trees can be propagated from seed, cuttings or by grafting. Although not easily rooted, cuttings from mature plants will produce blooms within two years, whereas seedlings may take 15 years or more to flower. Cuttings should be taken in summer and it is best to plant them in quantity due to the low success rate with this method. Seeds can be gathered in the fall when fully ripe and stored in a chilled environment over the winter for spring planting.
There are many varieties of magnolia grandiflora, including several smaller types that are well suited to smaller gardens. The Little Gem variety is quite popular as it rarely grows more than 12 feet tall and begins flowering at an early age. The hardy Exmouth is another popular type that grows as a tall shrub. It normally grows to 20 feet in height unless pruned back.