LSUAg Horticulturist says its now time to plant Southern magnolias

By Myra Miller on Thursday, January 25, 2018

By Dan Gill
LSU AgCenter Horticulturist
January and February are excellent moths to plant trees in Louisiana. If you are thinking about adding shade trees, small spring- or summer-flowering trees or trees for screening, head out to local nurseries and purchase and plant trees in the next few weeks. Arbor Day in Louisiana was on January 19 this year. It’s always the third Friday in January because this is such a good time to plant trees here.
Where a medium-to-large evergreen tree is desirable, the Southern magnolia (Magnolia grandiflora) can be a wonderful choice. The Southern magnolia is well known as a traditional tree for Louisiana landscapes. Like camellias, azaleas and crape myrtles, it is often considered essential for creating a “Southern” style garden. Unlike camellias, azaleas and crape myrtles, however, which are all native to the Far East, the Southern magnolia is native to Louisiana and the southeastern U.S.
One of the remarkable things about our native Southern magnolia is that it retains its foliage year-round — most magnolia species around the world are deciduous. And what outstanding foliage it is; deep green and lustrous, the leaves may be 4 to 8 inches long and often have attractive rusty brown undersides.
The evergreen habit of magnolias is most noticeable in winter when the green foliage, along with other broadleaf evergreen trees such as live oaks and hollies, provides welcome relief to the bare, leafless branches of deciduous trees.
The flowers also make this tree popular. At about 8 inches across, the size of the white flowers is unusually large for the genus, and they stand out beautifully against the dark green foliage. (The species name, grandiflora, means large flower.) The Southern magnolia is the state flower of Louisiana.
Flowers generally appear in greatest abundance beginning in late April, peak in May and diminish in early June. But flowering continues sporadically through the summer, and flowers may appear as late as September or October. The lemony fragrance of magnolia flowers fills the sultry summer air and is downright intoxicating if you stick your nose right into a flower and take a whiff.
The Southern magnolia is a medium- to large-growing tree that can reach well over 60 feet tall. But on average, trees tend to be around 40 to 50 feet tall with a spread of 20 to 30 feet. Left to grow on its own, a magnolia tree will retain its lower branches creating a canopy that starts at ground level. Trees allowed to grow this way are outstandingly beautiful (and kids love to play among the shelter of the low branches), but you must have enough room in your landscape for this to be practical. In most situations, it’s best to gradually remove the lower branches as a young tree grows taller. This continues until the canopy is as high as you need it to be, generally at least 8 to 10 feet from the ground.
If you don’t have room for a typical Southern magnolia in your landscape, some dwarf cultivars stay much smaller. The most popular dwarf is a cultivar called Little Gem. Its smaller size, about 20 feet tall with a spread of about 8 feet, makes it useful where a typical Southern magnolia would be too large. The foliage is an especially nice glossy deep green with brown backs, and the flowers are produced over an unusually long period, often appearing as late as October. Teddy Bear is another compact-growing cultivar you will find in nurseries. It grows to be about 20 feet tall and 10 feet wide.
Southern magnolias are best planted from November through March when the weather is cool and while the plants are dormant. Magnolia roots are very sensitive to the depth of plantings, so it is critical that the top of the rootball be at or slightly above the surrounding soil. If planted too deeply or in a location not to their liking, magnolia trees tend to grow poorly and stay stunted. A happy, well-established young tree, on the other hand, will grow moderately fast, especially if fertilized each spring.
Be aware that even though they are evergreen, magnolias drop leaves abundantly in spring and early summer. They also drop old petals when they are in bloom and seed cones and a few more leaves in late summer and fall. Given this, it’s best to locate these trees away from outdoor living areas, pools and driveways where stuff dropping out of the tree will not be a major nuisance.
Initially, Southern magnolias have an upright pyramidal habit when young, which gradually changes into a broader canopy with a rounded top as trees age.
The large evergreen leaves cast a deep shade as the trees mature, often preventing grass from growing around them. The ideal way of dealing with bare areas under magnolias is to simply apply a 4-to-6-inch layer of mulch, such as leaves, pine straw or bark. This is best for the tree’s health. Magnolias also produce large surface roots, so locate them well away from concrete surfaces such as driveways, patios and sidewalks.
Excellent cultivars currently available include D. D. Blanchard, Bracken’s Brown Beauty and Alta; the dwarf Little Gem and Teddy Bear; and many others. The advantage of named cultivars is that you can pick one that has the characteristics you prefer, including size, shape, foliage characteristics and bloom season.