Tree · Magnoliaceae
Southern Magnolia
Magnolia grandiflora
A grand, forgiving evergreen whose glossy leaves and lemon-scented white blooms will reward your garden for generations.
Full sun
Every 7–14 days
USDA 6–10
60–80 ft · 18.3–24.4 m
Overview
If the American South has a signature tree, the southern magnolia is it, and it is far kinder to grow than its grandeur suggests. Give it time and it settles into a stately 60 to 80 feet (18 to 24 m), its thick, leathery leaves shining dark green above and often lined with soft rusty-brown felt beneath. Come late spring and summer, big white flowers unfurl, each one cup-shaped and lemon-scented, and the whole yard fills with their perfume.
Think of this as a tree for the long haul, one that simply needs room to be itself. It throws dense year-round shade and sends out wide, shallow surface roots, so coaxing a lawn to grow right beneath it is a struggle you do not need to take on. It also drops leathery leaves, spent flowers, and cone-like fruit through most of the year, so a bit of steady tidying comes with the territory. Pick a generous spot away from lawns and foundations and that mess becomes a non-issue.
Set it in the right place and it asks for very little in return, which is reassuring if this is your first big tree. It wants rich, moist, acidic soil and steady watering while it finds its feet, then largely takes care of itself, shrugging off serious pests apart from the odd visit of scale. Newer cultivars have carried it well north of its old range, so even cooler gardens can give one a happy home.
Care
The short version: give it full sun to part shade and rich, steadily moist acidic soil, water deeply through dry spells while it is young, and prune little beyond the occasional dead or crossing branch. Get those basics right and the tree forgives the rest.
Light
Southern magnolia is happiest in full sun, yet it takes partial sun and partial shade in good stride, so do not fret if your spot catches some shadow. More sun rewards you with denser growth and a heavier show of flowers, while a shadier corner simply gives you a looser, more open tree. Either way, it will grow.
Water
Aim to keep the soil consistently moist, watering deeply during dry spells and especially while the young tree is settling in. Once it is established, a good soak every 7 to 14 days in dry weather is plenty. It does not like to sit in either prolonged drought or standing water, so steady and even is the goal you are after.
Soil
Plant it in rich, well-drained loam that holds moisture and is generous with organic matter. The tree leans acidic and is at its most content around a pH of 5.0 to 6.5. It will put up with clay, though soggy or extreme ground will test its patience, so give it something crumbly and kind if you can.
Temperature
This tree copes with a wide swing of weather, from about -9°F to 100°F (-23°C to 38°C), which comfortably covers Zones 6 through 10. If your garden sits at the cold northern edge, a hardy cultivar is the reassuring choice that takes the worry out of a hard winter.
Humidity
Ordinary outdoor air suits it fine, so there is no humidity target for you to chase. In warm, muggy spells you may notice algal leaf spot, but it is only cosmetic and nothing to lose sleep over.
Feeding
Feed just once in spring with a balanced or acid-forming slow-release fertilizer made for acid-loving trees. A light hand is best, since too much nitrogen pushes soft new growth that scale insects are only too glad to find.
Pruning
Happily, this tree needs little pruning. Take out any dead, damaged, or crossing branches in late winter to early spring, and feel free to let the low limbs sweep the ground if you would rather they hide the fallen leaves than reveal a bare trunk.
Repotting
A tree in the ground never needs repotting, and even a container plant is moved only rarely, so relax on that front. When a nursery plant has outgrown its pot you will see roots circling the rootball, roots pushing out the drainage holes, and water running straight through instead of soaking in.
Size & spacing
Plan from the start for a big tree, 60 to 80 feet (18 to 24 m) tall and 30 to 50 feet (9 to 15 m) wide. Offer it that whole footprint of open ground, clear of buildings and lawn, and both the spreading canopy and the surface roots will have all the room they need to thrive.
When to plant
This is a tree you plant once and enjoy for decades, not a crop you race the calendar to sow. Set it out in spring or fall while the weather stays mild and the roots can settle gently. After that the only dates worth watching are its own, the big white flowers that open from late spring into summer, heaviest in May and June and drifting on here and there afterward.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall
- Harvest: Late spring to summer (May to June, with sparse continued flowering through summer)
Hardiness
USDA hardiness zones: 6–10
Temperature: down to -23°C
Troubleshooting
A healthy southern magnolia rarely asks much of you, and the handful of problems it can meet almost always show up on the twigs or the leaves where they are easy to spot. Catch them early and nearly all are simple to put right, so there is no need to worry. Find the symptom that matches yours below and act while the trouble is still small.
Whole branches wilting and dying back one by one
When scattered branches wilt and brown out on their own, the usual culprit is verticillium wilt, a soil fungus that quietly plugs the wood from the inside. Slice into the bark and you may find dark streaks in the vascular tissue, though only a lab test gives a firm answer. There is no chemical cure, so prune away the dead wood and keep the tree strong with steady water and feeding, and it can carry on for many good years.
Fix:
- Prune out and destroy affected dead branches
- Fertilize and water during dry weather to support recovery
- There is no chemical cure; keep the tree vigorous
Waxy white lumps on the twigs with a sticky, dark film on the leaves below
Those raised, shell-like lumps are magnolia scale, one of the very few pests that troubles this otherwise easygoing tree. As they feed they drip honeydew, and a black sooty mold settles over it on the leaves beneath, which looks worse than it really is. Prune out the worst twigs, smother overwintering scale with horticultural oil in the dormant season, and treat the crawlers in late summer, and the tree bounces right back.
Fix:
- Prune out and destroy heavily infested twigs
- Apply horticultural oil during the dormant season to smother overwintering scale
- Treat crawlers in late summer when young scales are active
Spots and blotches on the leaves, with a little early leaf drop
Most of the leaf spots you will see here are fungal or bacterial, and in warm, humid weather the greenish-gray patches of algal leaf spot can join them. The good news is that none of it does any lasting harm. Rake up and bin the fallen leaves, open the canopy with a little light pruning so air moves through, and you can safely skip the sprays, which are rarely worth the bother.
Fix:
- Rake up and dispose of infected fallen leaves
- Improve air circulation by spacing and selective pruning
- Chemical control is rarely needed
Toxicity
Here is one less thing to fret over: the southern magnolia is safe. The ASPCA lists magnolia as non-toxic to cats, dogs, and horses, and nothing in the tree will poison people, livestock, birds, or rabbits. The worst a big mouthful of leaves might bring is a brief, mild bout of stomach upset, no different from many other plants.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists magnolia as non-toxic to cats, so a nibbled leaf is truly no cause for alarm. A cat that gorges on foliage might drool or bring it back up once, the way any rough plant material can unsettle a stomach for a moment.
Dogs None
Dogs can chew the leaves with no poisoning risk at all. The most a big mouthful is likely to bring is a short bout of vomiting or a loose stool while the fibrous bits pass through, and then all is well again.
Horses None
Horses are in the clear too, with magnolia sitting on the ASPCA non-toxic list. The tough, leathery leaves are not a favorite browse anyway, and a stray mouthful will do no harm.
Rabbits Safe
There is no toxin here to threaten a rabbit. Their gut copes best with only small amounts of new greenery, so treat the odd leaf as a harmless curiosity rather than part of the daily diet.
Livestock Safe
Cattle, goats, and sheep can graze happily near a southern magnolia, since nothing in the tree is poisonous to them. They tend to leave the stiff evergreen leaves alone in any case.
Birds Safe
The tree holds no chemical danger for birds, which often shelter and nest in its dense, welcoming canopy. Some will pick at the bright red seeds in fall without any trouble at all.
People Safe
Southern magnolia is not poisonous to people, and no part is known to harm anyone who handles it. The leaves and flowers are not a food, though, so there is simply no reason to eat them.
As with any plant, ingestion of plant material may cause mild, transient gastrointestinal upset even though the plant is non-toxic.
Varieties
A few named selections gently refine the wild tree, giving up a little height in exchange for extra cold tolerance, smaller leaves, or a neater shape. If you are choosing your first magnolia, these are the friendly names to know.
Little Gem
A compact semi-dwarf that tops out near 30 feet with smaller leaves and flowers, starts blooming while still young, and slips happily into a yard too small for the full-size tree.
Bracken's Brown Beauty
A cold-hardy, compact pick that holds up all the way to Zone 6, its smaller leaves backed with a thick, cozy rusty-brown felt underneath.
Edith Bogue
One of the toughest choices for a harsh site, loved for shrugging off cold, wind, and heavy snow without complaint.
D.D. Blanchard
A vigorous grower that reaches about 75 feet on a straight, handsome trunk, dressed in dark glossy leaves with rich brown undersides.
How to propagate
You can raise a southern magnolia from seed or clone one you already love, and while none of it is quick, none of it is beyond a patient gardener either. Which route suits you comes down to whether you need to hold on to a particular cultivar's traits.
SeedModerate
Sow cleaned seed in fall or after cold stratification · Several months to germinate; years to reach flowering size
Start by stripping off the red fleshy coat, then sow the cleaned seed in fall or give it a cold spell first to wake it up. Germination takes several months, and a young seedling needs years to reach flowering size as it builds its strong taproot, so patience is part of the deal. Seed will not copy a named cultivar, so choose it only when you are glad to welcome whatever grows.
Air layeringModerate
Spring to summer on actively growing wood · Several months to root
Air-layering is the most dependable way to clone a southern magnolia and keep its cultivar traits intact, which makes it a reassuring choice. Work on actively growing wood from spring through summer, and give it several months to root well before you separate the new plant from its parent.
Stem cuttingsDemanding
Semi-hardwood cuttings in summer · Several weeks to months under mist
Take semi-hardwood cuttings in summer, dip them in rooting hormone, and keep them cozy under mist. Rooting here runs slow and a little uneven, anywhere from several weeks to a few months, so this is the method that gently tests your patience the most.
GraftingDemanding
Late winter to spring · One or more seasons to unite
Grafting from late winter into spring joins a named cultivar onto seedling rootstock so the new tree keeps its parent's good looks. The union needs one or more seasons to knit together firmly, and the technique does call for a practiced hand, so it is one to grow into.
Myths
Southern magnolia is poisonous to dogs and cats.
You can breathe easy here, because the ASPCA lists magnolia as non-toxic to dogs, cats, and horses, so a curious pet that chews a leaf is in no real danger. The most you might see is a brief, mild tummy upset, the same thing almost any plant can cause. You can plant it around pets without worry.