The Southern magnolia (Magnolia grandiflora) is a broadleaf evergreen tree that can reach heights of 60 to 80 feet, with a 40-foot spread. The Southern magnolia blooms in late spring and early summer with large, white or cream-colored flowers that emit a pleasing fragrance. This magnolia tree grows best in USDA Hardiness Zones 6 through 10, where minimum winter temperatures stay warmer than 0 to -5 degrees Fahrenheit. The Southern magnolia is easy to care for and requires little shaping or pruning.
Water your Southern magnolia trees deeply once each week during the first three growing seasons, soaking the soil down to and around the entire root area. In subsequent years when the trees are well-established, water them deeply during the growing season when prolonged dry spells or droughts occur.
Spread a 3-inch layer of bark mulch on the ground beneath the Southern magnolias to control weeds and retain soil moisture. Extend the mulch ring so that it covers the entire root zone.
Feed your Southern magnolia trees with a 10-10-10 NPK fertilizer at half the recommended dosage once every two weeks during the first three growing seasons. Begin fertilizing the trees about one month to six weeks after planting them.
Fertilize your Southern magnolia trees once each year in the spring during subsequent growing seasons with a slow-release tree fertilizer. Follow the dosage directions on the label.
Prune your Southern magnolias in late winter to remove any dead, broken or damaged branches. Prune the trees lightly to maintain their pyramid shape and to remove any crossing branches.