Tree · Altingiaceae
Sweetgum
Liquidambar styraciflua
Give a sweetgum deep, acidic soil and plenty of sun, and this easygoing shade tree thanks you with star-shaped leaves and a blaze of fall color.
Full sun
Every 7–14 days
USDA 5–9
60–100 ft · 18.3–30.5 m
Overview
If you have the room for it, the sweetgum is a wonderfully forgiving native of the eastern United States, and you will know it at a glance by its star-shaped leaves and the corky, ridged bark along its trunk. Given space to stretch, it climbs to 60 to 100 feet (18 to 30 m) with a broad, pyramidal crown, so this is a tree for an open yard rather than a tight corner. Do not let the size worry you, since a settled sweetgum asks for very little.
The real reward arrives in autumn, when the leaves warm through yellow, orange, red, and deep purple, often wearing several of those shades on a single branch at once. There is one honest catch worth knowing in advance, because a mature female tree sets a generous crop of spiny gumball seed capsules that come down and scatter across the ground from December into spring. It is nothing you cannot manage, and many growers simply rake them up or choose a fruitless variety from the start.
Here is the reassuring part: get the planting spot right and the rest looks after itself. A sweetgum is happiest in deep, moist, acidic ground with full sun, and its only real sulk is alkaline soil, which turns the leaves yellow. Give it open space away from curbs and walkways, because the shallow roots spread wide and the fruit can be untidy, and you will have a tree that mostly takes care of itself.
Care
The short version: set your sweetgum in full sun and deep, moist, acidic soil with a pH of 7 or less, keep young trees watered through their first seasons, and leave it plenty of open room away from paving so the surface roots and falling gumballs have somewhere to go.
Light
Sweetgum does its best work in full sun, where it builds the sturdiest shape and the brightest autumn color. It will happily accept partial sun or partial shade if that is what you have, but the more light you can offer, the more it gives back.
Water
While a young tree is settling in, keep the soil steadily moist and water again through any dry spell, giving it a deep drink every 7 to 14 days as it establishes. It loves deep, moist bottomland ground, yet you can relax later, because a grown sweetgum becomes fairly drought tolerant once its roots reach down.
Soil
Aim for deep, moist, fertile, slightly acidic loam that drains freely, though your sweetgum will forgive a little clay or sand. The one number to remember is pH, which should sit at 7.0 or less, anywhere from 5.5 to 7.0, since alkaline ground locks away iron and yellows the leaves.
Temperature
This is a tough tree that shrugs off a wide swing of weather, from about -20°F to 95°F (-29°C to 35°C). That resilience is what makes it feel at home across USDA zones 5 to 9.
Humidity
There is nothing to fuss over here, since ordinary outdoor air suits a sweetgum just fine. As a large landscape tree, it simply takes whatever humidity your local weather brings.
Feeding
Once it is established, a sweetgum hardly ever needs feeding, so you can leave the fertilizer on the shelf. Offer a balanced complete fertilizer in early spring only if growth looks weak, and turn to chelated iron or sulfur if high-pH soil brings on the yellowing of iron chlorosis.
Pruning
Happily, this tree needs very little pruning. In late winter you can trim out any dead, damaged, or crossing branches, and gently guide a strong central leader while the tree is still young.
Repotting
A sweetgum belongs in the ground rather than a pot, so once it is planted there is no repotting to worry about. If a nursery tree shows roots circling the container, poking from the drainage holes, or stalled top growth, it has outgrown its pot and is ready for the earth.
Size & spacing
Picture a large tree in time, reaching 60 to 100 feet (18 to 30 m) tall and spreading 40 to 60 feet (12 to 18 m) across. Plant it at least 8 to 10 feet from curbs and paving, which keeps those strong surface roots from lifting hard surfaces later on.
When to plant
Sweetgum takes its time getting going, so the kind thing is to let the roots settle before any stress arrives. You can cold-stratify seed over winter and sow it from late winter into spring, or make life easier and set out a young nursery tree in spring, which hands the shallow, slow-to-root system a whole season to find its footing. It is a hardy tree, comfortable across USDA zones 5 to 9.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter after 1-3 months cold stratification
- Plant: Spring (preferred) due to shallow, slow-to-establish root system
- Harvest: Inconspicuous yellow-green flowers April to May; spiny gumball fruits ripen in fall and drop December to April
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Take heart, because most sweetgum troubles are cosmetic or simply a sign the spot is not quite right, not the end of your tree. The two worth your attention are yellowing in alkaline soil and the fall of the gumballs. Find your symptom below and step in while it still does some good.
Sunken cankers weeping dark sap on the trunk
When the trunk shows sunken, discolored patches that weep dark sap and the branches begin to die back, you are looking at bleeding canker disease. It tends to take hold after stress or a wound, so a tree strained by drought or freshly transplanted is the one most at risk. Prune the affected branches well below the canker and burn them, keep the tree watered and well placed, and take care not to let mowers or trimmers nick the bark.
Fix:
- Prune out and destroy affected branches well below cankered tissue
- Maintain vigor with adequate water and proper siting
- Avoid mechanical trunk wounds from mowers and trimmers
Yellowing leaves that keep their green veins
Do not lose heart if the newest leaves go yellow while their veins stay green, because this is iron chlorosis and it is very fixable. It shows up when the soil turns too alkaline for the roots to pull in iron, so a soil test reading above 7.0 will confirm what is happening. Ease the pH down with elemental sulfur, feed chelated iron to the soil or as a leaf spray, and clear up any soggy drainage that is holding iron out of reach.
Fix:
- Test and lower soil pH toward acidic with elemental sulfur
- Apply chelated iron to soil or as foliar spray
- Improve drainage and avoid planting in alkaline sites
Chewed foliage and silken nests in the branches
A handful of leaf-eaters may visit a sweetgum, chiefly fall webworm, along with tent caterpillars, bagworms, and leaf miners that chew the foliage and spin silken nests. Scale insects and borers usually only move in on a tree that is already stressed. Prune out and destroy the nests, treat scale with horticultural oil, and keep the tree strong so borers find no way in, knowing that a healthy established tree can shrug off a little caterpillar nibbling.
Fix:
- Prune out and destroy webworm and bagworm nests
- Control scale with horticultural oil; keep trees vigorous to limit borers
- Tolerate minor caterpillar feeding on healthy established trees
Spiny seed balls scattered across the lawn
Those knobby little spheres are the tree's gumballs, the perfectly normal woody seed capsules that a mature female tree lets go in great numbers from December to April. Each one is about 1 to 1.5 inches across and can turn into a nuisance underfoot for walking and mowing. The easy answer is to rake them up as they drop, or to skip the bother altogether by planting a fruitless cultivar such as Rotundiloba and keeping the tree well clear of paths and play areas.
Fix:
- Rake and remove gumballs regularly
- Plant fruitless or low-fruit cultivars such as Rotundiloba where litter is a concern
- Site the tree away from walkways, patios, and play areas
Spotted leaves dropping early in the season
Spots on the leaves that bring on an early leaf drop point to fungal leaf spot, and it turns up mostly in a wet spring or summer. It looks far worse than it really is, so there is no need to reach for a fungicide. Rake up and bin the fallen leaves to clear away the spores, keep your tree in good health, and it will come back next year.
Fix:
- Rake and remove fallen leaves to reduce inoculum
- Maintain good air circulation and tree vigor
Toxicity
Good news if you share your home with pets or little ones: the sweetgum is not poisonous. The ASPCA does not list it as toxic to cats, dogs, or horses, and no part of the tree will harm an animal that takes a curious nibble. The one thing to keep an eye on is physical rather than chemical, since the hard, spiny gumballs can prick a paw or become a choking risk for a pet or child who picks one up.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
No poisoning worries here. A cat can rub against the leaves and bark without any harm, though a spiny gumball underfoot might still give a paw a sharp prick.
Dogs None
Perfectly safe company for a dog. The leaves hold no toxin, so the only thing to keep an eye on is a dog mouthing a hard gumball, which is a choking or obstruction risk rather than a poisoning one.
Horses Safe
Not toxic to horses in any way, since sweetgum carries no compound that could poison a grazing animal.
Rabbits Safe
No chemical danger to rabbits at all, because the plant simply is not poisonous.
Livestock Safe
Cattle, goats, and sheep can share a pasture with a sweetgum quite safely, with no risk of poisoning.
Birds Safe
Completely harmless to birds, which are glad to feed on the seeds tucked inside the dried gumballs.
People Safe
Not poisonous to people either. The only real caution is the spiny seed ball, which is easy to turn an ankle on or for a small child to pop in their mouth.
No poisoning risk from foliage. Watch pets and children around fallen spiny gumballs, which can injure paws and feet or cause obstruction if swallowed.
Varieties
Most of the named sweetgums were chosen to soften the two things people grumble about, the messy fruit and the wide spread, so there is likely one here that suits your yard. These are the selections worth knowing by name.
Rotundiloba
An essentially fruitless cultivar whose leaf lobes are rounded rather than pointed, which happily spares you the messy spiny gumballs.
Slender Silhouette
A slim, columnar tree only 5 to 6 feet wide that tucks into a tight spot and sets just a few fruits.
Worplesdon
A broadly pyramidal to oval tree with deeply cut, finger-like lobes and fall color that moves through purple, orange, and yellow.
Moraine
Said to be the most cold-hardy of the group, and it turns a reliable red every autumn.
Burgundy
A tree that wears deep burgundy-red fall foliage, though it takes the cold a little less easily than the others.
How to propagate
Sweetgum is usually grown from seed, while the named cultivars are grafted so they stay true to type. Cuttings can be done, though they test your patience, so seed and grafting carry most of the work.
SeedModerate
Sow stratified seed in late winter to spring · Seedlings establish over 1 to 2 growing seasons; some seed may take up to 2 years to germinate
Seed is the usual and friendliest route. Gather the ripe capsules in fall, shake the seed loose, and give it a cool rest of 1 to 3 months before sowing from late winter into spring. Be patient with it, since germination comes slowly and unevenly and some seed will sit for up to two years, with the seedlings settling in over one to two growing seasons.
Stem cuttingsDemanding
Summer, from half-ripe (semi-hardwood) wood · Several months to root, often with low success
Cuttings are the trickier path. Take half-ripe semi-hardwood in summer and give it bottom heat and a little rooting hormone, but be ready for several months of waiting and a low success rate even so. Seed really is the gentler choice.
GraftingDemanding
Late winter to spring onto seedling rootstock · One to two seasons to establish a grafted plant
Because named cultivars will not come true from seed, growers graft or bud them onto seedling sweetgum rootstock from late winter into spring. That is how a fruitless Rotundiloba keeps its fruitless character, and a grafted tree needs one to two seasons to settle in.
Myths
Sweetgum gumballs are poisonous and will make a dog or cat sick if they touch or chew one.
You can breathe easy, because the ASPCA does not list sweetgum as toxic and it counts as non-toxic to both cats and dogs. The gumballs are a mechanical hazard, not a poison, spiny enough to hurt a paw or block a throat if one is swallowed, yet they carry nothing that will actually poison your pet.
Planting a Rotundiloba sweetgum guarantees a completely fruitless tree for good.
Rotundiloba is the one selection described as essentially fruitless without any qualifier, so it is your best bet for a clean lawn. Still, low-fruit cultivars like Slender Silhouette can drop a few gumballs over the years, which means fruitless is really the goal to aim for rather than an ironclad promise.