The southern magnolia tree (Magnolia grandiflora) is the broad-leaved evergreen that gives the American South its signature look: glossy, leathery foliage all year, and dinner-plate flowers in early summer that perfume an entire yard. It is a magnificent specimen, but it is also a big, long-lived tree with a few habits worth knowing before you dig the hole. Get the site and the cultivar right and you will be rewarded with decades of fragrant blooms and dense, dark-green shade. Get them wrong and you may wait a decade for a single flower, or spend every spring raking leathery leaves out of your lawn.
This guide walks through everything you need to plant and care for a southern magnolia: how big it really gets, where to put it, how to water and feed it, which cultivar fits your space, and why a healthy tree sometimes refuses to bloom.
What a southern magnolia tree looks like and where it grows
Southern magnolia is a large, broadleaf evergreen native to the bottomlands and moist woods of the southeastern coastal plain, from North Carolina south to Florida and west to Texas. In the wild it often grows as an understory tree, which is why it tolerates both sun and shade so gracefully in the garden.
The leaves are its first calling card. They are stiff, leathery, and laurel-like, 5 to 10 inches (13 to 25 cm) long, glossy dark green on top and felted with a rusty-brown fuzz underneath. Because it is evergreen, that canopy stays full and dark through winter when most trees are bare. The flowers are the second draw: creamy-white, cup-shaped, and enormous, often 8 to 12 inches (20 to 30 cm) across, with a sweet, lemony fragrance. They open mainly in late spring and early summer, with scattered blooms continuing into the warm months. When the petals drop, the tree forms woody, cone-like fruits that split open in fall to reveal bright rose-red seeds on slender threads, a favorite of birds and small mammals.
Southern magnolia is hardy in USDA zones 6 through 10, which means gardeners across much of the country can grow it, not just in the Deep South. In colder zones, shelter it from harsh winter sun and wind, and lean toward a cold-hardy cultivar like Bracken’s Brown Beauty or Edith Bogue.
How big does a southern magnolia tree get
This is the single most important question to settle before planting, because the answer surprises people. A full-size southern magnolia typically reaches 60 to 80 feet (18 to 24 m) tall with a spread of 20 to 50 feet (6 to 15 m) and a trunk up to 3 feet thick. It grows fast for a tree of its size, putting on 12 to 24 inches (30 to 60 cm) a year, so a slender sapling becomes a substantial tree within a decade.
Two traits make that mature size more demanding than the numbers alone suggest. First, the lower branches naturally sweep all the way to the ground, so the tree occupies its full width from top to bottom unless you limb it up. Second, the root system is shallow and wide. Magnolia roots have been shown to spread more than three times the width of the canopy, which is why turf and other plants struggle directly beneath the tree and why surface roots eventually appear.
For these reasons, give a standard southern magnolia plenty of room and keep it well away from foundations, septic lines, and driveways. As a rule of thumb, site a full-size tree at least 15 to 20 feet (4.5 to 6 m) from your house and other structures. If your space is tight, do not try to prune a giant into submission. Choose a compact cultivar instead, covered further down.
Where to plant a southern magnolia for the best results
Southern magnolia is forgiving about light. It performs in full sun to partial shade, and while it will grow with as little as four hours of direct sun, full sun produces the fullest canopy and the most flowers. In hot southern gardens, a little afternoon shade is fine.
Soil is where the tree is fussier. It prefers deep, rich, moist, well-drained soil that is acidic to roughly neutral, ideally in the pH 4.5 to 6.5 range. It adapts to clay, loam, and high-organic-matter soils and tolerates fluctuating moisture, even occasional wet spells, but it resents prolonged flooding and standing water. If your soil is heavy and stays soggy, improve drainage or plant on a slight rise.
Plant in a bed, not in the middle of the lawn
The most useful siting advice is also the most overlooked: do not plant a southern magnolia in the center of a lawn you care about. The tree drops old leaves every spring and sheds seed pods in late summer, and those thick, slow-to-decompose leaves are a chore to rake out of grass. Worse, almost nothing grows in the dense shade and competitive roots beneath it.
Instead, plant it within a defined ornamental bed, on its own or among shrubs, and let the fallen leaves stay put as a natural mulch that recycles nutrients back to the tree. Used this way as a specimen or backdrop, a southern magnolia is far less work and far better looking. A row of them also makes a superb evergreen screen for blocking views or marking a property line.
How to plant a southern magnolia tree
You can plant container-grown southern magnolias at almost any time of year. Balled-and-burlapped trees transplant best from August through October, when the weather is cooling but the soil is still warm.
Follow these steps when you plant:
- Dig the planting hole at least twice as wide as the root ball and roughly as deep, then loosen the sides so roots can push outward.
- Set the tree so the top of the root ball sits slightly higher than the surrounding soil, never buried below grade.
- Backfill with the native soil you removed, breaking up clods and pulling out stones, then water thoroughly to settle out air pockets.
- Spread 3 to 4 inches (8 to 10 cm) of mulch over the root zone to conserve moisture and suppress weeds, but keep the mulch off the top of the root ball itself, where a thick layer can shed water away from the roots.
- On windy, exposed sites, stake the tree for its first season. Run any guy wire through a length of old garden hose where it wraps the trunk so it cannot girdle the bark.
One thing not to worry about: if your newly planted magnolia drops a flush of leaves during its first season, that is ordinary transplant shock for this species, not a sign of failure.
How to water and care for a southern magnolia
Care is straightforward once you understand that a southern magnolia is needy while young and largely self-sufficient once established.
Watering eases off as the tree settles in
For the first growing season, keep the root zone consistently moist, aiming for at least an inch of water a week from rain or irrigation, more during dry spells. The goal is steady moisture without waterlogging, since the roots will rot in soil that stays saturated. After the first year or two, an established southern magnolia gets by on rainfall in most regions and only needs supplemental water during prolonged drought.
Feed lightly while the tree is getting established
Southern magnolia is a light feeder, and a mature tree in decent soil rarely needs fertilizer at all. Where you can speed up a young tree, do it with light, frequent feeding during the first three growing seasons rather than one heavy dose. A balanced, slow-release tree-and-shrub fertilizer applied in spring is plenty; products containing some iron or sulfur help keep the foliage deep green in alkaline soils. Wait until a newly planted tree is putting out fresh growth before you feed it at all, and never push it with high-nitrogen fertilizer, which produces lush leaves at the expense of flowers.
Prune only to shape, and leave the lower limbs if you can
Southern magnolia needs very little pruning. Remove dead, damaged, or crossing branches, and take out the occasional stray limb that spoils the tree’s naturally pyramidal form. If you want a clean, tree-like trunk you can walk under, limb up the lowest branches, but the tree honestly looks its best when allowed to keep its skirt of foliage to the ground. Time any pruning for after the tree blooms or during summer so the cuts heal well before winter.
As for pests, this is a notably tough tree. It has few serious problems; scale insects are the most common, and southern magnolia is moderately deer-resistant, salt-tolerant, and able to shrug off wind, storms, and urban conditions.
Why your southern magnolia is not blooming
A southern magnolia that grows well but refuses to flower is one of the most common frustrations gardeners have with this tree, and the cause is usually one of a handful of things.
The first is simply age and origin. Trees grown from seed or sold as ungrafted seedlings can take 8 to 13 years, sometimes longer, before they bloom for the first time. If you want flowers sooner, this is the strongest argument for buying a named, vegetatively propagated cultivar, many of which flower at a much younger age.
The other common causes are environmental. Late frost is the classic flower-killer, nipping the developing buds before they open. Too much shade reduces flowering, so a tree that has been crowded out by larger neighbors may need more light. Over-fertilizing, especially with high-nitrogen feed, drives leafy growth instead of blooms. And water stress, particularly a dry fall when next year’s buds are forming, can also cost you flowers. Correct the cause, give the tree a season or two, and the blooms usually return.
How to choose the right southern magnolia cultivar for your space
The single best decision you can make is matching the cultivar to the space you actually have, because that determines both how much room the tree needs and how soon it will bloom. Modern named cultivars also tend to have denser, tidier canopies and flower younger than seedling trees.
- Little Gem is the compact favorite for small yards and tight spaces, maturing at about 20 to 25 feet (6 to 7.5 m) tall and 10 to 15 feet (3 to 4.5 m) wide. It is sometimes called a dwarf, though it can stretch toward 30 feet in time. It produces 4- to 6-inch flowers over an exceptionally long season and works well as a narrow screen.
- Bracken’s Brown Beauty is the cold-hardy choice, reliable into zone 6, reaching roughly 30 to 50 feet (9 to 15 m) tall and 15 to 25 feet (4.5 to 7.5 m) wide with a tight pyramidal shape, smaller leaves, and a rich rusty-brown leaf underside.
- D.D. Blanchard suits larger properties, growing 50 to 60 feet (15 to 18 m) tall with strikingly coppery leaf undersides and big 8- to 10-inch flowers; it makes a dramatic, full-size specimen.
- Teddy Bear and Kay Parris are other good semi-dwarf and compact selections, while Edith Bogue is prized for cold and storm hardiness.
For a small or suburban lot, start with a compact cultivar like Little Gem or Teddy Bear rather than the species. Save the towering 60- to 80-foot trees for the open spaces and large landscapes where they have room to show off, lower limbs and wide roots and all. Choose the right tree for the spot and a southern magnolia becomes one of the most handsome, durable, and low-maintenance evergreens you can grow.