The southern magnolia--or Magnolia grandiflora--is the iconic native tree of the American South. It is known for its graceful shape; large, glossy, leathery leaves; and very large, sweet smelling flowers. Trees can grow to 80 or 90 feet tall and 40 to 50 feet wide, with trunks 4 feet in diameter. This stately evergreen tree stands out in winter, when all deciduous trees stand bare. It's a standout also when in bloom and when its bright red seeds mature, much to the delight of birds. The southern magnolia is easy to plant and care for.
Choose a suitable, spacious planting site. The southern magnolia does best in rich, moist but well-draining soil, yet it is surprisingly adaptable to drier soils. The tree thrives in full sun or partial shade.
Prepare the soil by digging to loosen compacted soil, then cultivate deeply. Add compost and organic matter and cultivate again, to a depth of at least 12 inches, to mix soil and all amendments.
Dig a planting hole as deep as the root ball and at least twice as wide. Carefully remove the root mass from the container and set the plant in the hole. Make sure the top of the root ball is level with the surrounding soil. Backfill the hole with soil, thoroughly covering roots and packing the soil around them.
Water thoroughly to settle the soil, completely saturating the entire root area. Water every few days for the first few weeks to minimise transplant shock. Irrigate young trees regularly--for at least the first 3 to 5 years--until they are well established.
Mulch with coarse compost or wood mulch, to conserve soil moisture and also keep the soil cool. Use the “doughnut hole” method--with the tree’s trunk at the centre of the doughnut hole--to prevent mulch from touching the tree. Spread mulch 4 inches thick under the tree’s canopy.
Provide filtered shade in summer for young southern magnolia plants. Make a simple shade canopy by driving four T-posts in a square pattern around the tree. Stretch a shadecloth or burlap between the poles and attach near the top.
Fertilise every January or February, starting in the second year of growth, using organic fertilisers including cottonseed meal, bone meal and well-rotted cow manure. (Do not fertilise at all during the first year.)
Grow southern magnolias in a naturalised, bare area or ornamental bed, so lower branches can remain in place. As the tree matures, shedding old leaves in spring, seeds in summer and twigs year-round, detritus can collect and decompose unseen behind the tree&rsquo;s branches. Southern magnolias grown in containers can be planted any time of year. Transplant balled and burlapped trees from late summer into October.
Don&#039;t be alarmed if a newly planted tree drops a large number of leaves during its first growing season. This is a sign of transplant shock, which is not unusual with southern magnolia. The tree will be fine.