Tree · Platanaceae
American Sycamore
Platanus occidentalis
Hand it room and moist ground, and the American sycamore turns into one of the biggest shade trees in the East.
Full sun
Every 7–14 days
USDA 4–9
75–100 ft · 22.9–30.5 m
Overview
The American sycamore is a big one. It's native to the eastern United States, sits among the largest hardwoods on the continent, and grows fast, climbing 75 to 100 feet with a crown about as wide. You can pick it out instantly by the bark, which peels off in jigsaw-shaped flakes and leaves the upper trunk smooth, pale, and almost ghostly white.
Think of this as a tree for open ground, not tight lots. It wants deep, moist, rich soil and shrugs off wet spots, clay, sand, compaction, even the odd flood. The catch is all the litter: big leaves, peeling bark, twigs, and round buttonball seed heads drop all year long, and the heavy surface roots will heave pavement and crowd a foundation.
Give it the space it needs and it asks for very little back. The thing to keep an eye on is anthracnose, a spring fungus that browns the new leaves when the weather turns cool and wet, though the tree just leafs out again and rarely takes any lasting hit.
Care
The short version: full sun and deep, moist, rich soil, plus plenty of elbow room for a tree that clears 75 feet. Water young trees through any drought, prune while it's dormant, and rake up the leaf litter to keep anthracnose from getting a foothold.
Light
Sycamores want full sun and grow fastest out in the open, though they'll put up with a bit of partial shade. Crowding and deep shade just roll out the welcome mat for powdery mildew, so give the tree room and let the light in.
Water
This is a tree of stream banks and bottomland, so it loves deep, moist ground and even handles wet feet and short floods just fine. Dry soil cuts its life short, which is why young and establishing trees need watering through any drought. Once a tree's settled on a good site, it pretty much takes care of itself.
Soil
Few trees are this easygoing about soil. It does best in deep, moist, rich earth but tolerates clay, loam, sand, compaction, and high pH without a fuss. The one thing it can't stand is ground that stays bone dry.
Temperature
Hardy across USDA zones 4 through 9, the sycamore rolls with a big swing in weather, from roughly -29°F to 100°F (-34°C to 38°C). The real cold-weather worry isn't the tree itself, it's a cool, wet spring that gets anthracnose going on the fresh leaves.
Humidity
Outdoor humidity is just whatever the weather hands you, and the sycamore takes it all in stride. Airflow matters more than moisture in the air, since a crowded, shaded canopy is what gives powdery mildew and anthracnose a place to settle.
Feeding
A tree in good soil hardly ever needs feeding. Where the ground is poor, a balanced tree fertilizer in spring keeps a young or struggling sycamore vigorous, and that vigor is its best line of defense against disease.
Pruning
Prune while it's in dormancy, clearing out dead, crossing, or anthracnose-infected twigs. Haul the infected leaves and twigs away and destroy them instead of leaving them under the tree, where the fungus would just reinfect next spring's new growth.
Repotting
A sycamore belongs in the ground, not a pot, so it's rarely repotted. If you're keeping a young one in a nursery container, pot it up before the roots start circling or sneaking out the bottom and before the top growth quits climbing.
Size & spacing
Plan for a giant: this tree runs 75 to 100 feet tall, or 23 to 30 m, with a spread to match. Keep it well clear of pavement, foundations, and small lots, because between the strong surface roots and the sheer size there's no room to change your mind later.
When to plant
The American sycamore gets planted while it's still asleep. Put it in the ground in spring or fall during dormancy, keep an eye out for the easy-to-miss flowers in April, and look for the round buttonball seed heads to ripen and scatter anywhere from fall through the next spring.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall while dormant
- Harvest: Inconspicuous flowers in April; round buttonball seed heads mature and disperse fall through spring
Hardiness
USDA hardiness zones: 4–9
Temperature: down to -34°C
Troubleshooting
Just about every sycamore gripe shows up on the leaves, and on an established tree most of it is more of an eyesore than a real emergency. Match your symptom to the right entry below before you treat anything, because what knocks out a fungus won't touch an insect. Catch the early signs and you can step in while it still matters.
Burnt-looking leaf edges that keep getting worse yearly
If the scorch keeps coming back and creeping farther every year, you're probably looking at bacterial leaf scorch, a disease of the water-carrying tissue that sap-feeding bugs spread, and a lab test can pin it down. Drought on a tree that craves damp ground gives a similar burn, so rule that out first. Once the bacterium settles in there's no cure, but cutting out the worst branches, watering through dry spells, and keeping the tree strong can buy it years.
Fix:
- Prune infected branches
- Provide irrigation during drought
- Maintain vigor; antibiotic injections may suppress symptoms
Fresh leaves going brown just as they appear in spring
What you're seeing is sycamore anthracnose, a fungus that wakes up in a cool, wet spring and kills the new shoots about as quick as they open. It's at its worst when the weather at leaf-out sits below 55°F (13°C) for a week or two, and after a few rounds of dead twigs you get that stubby witches'-broom look. So what helps? Rake up and burn the fallen leaves and infected twigs, prune away the dead wood, and keep the tree watered and fed so it can throw a clean second flush of leaves.
Fix:
- Rake up and destroy fallen leaves and infected twigs
- Prune out blighted twigs and dead wood
- Maintain vigor with proper watering and fertilization
- Apply a labeled fungicide (chlorothalonil, thiophanate-methyl, or copper) on small trees if springs are wet
Chalky white bloom showing up on leaves and twigs
That chalky coating is powdery mildew, a fungus that likes crowded, shady growth and curls up the leaves before dropping them early. It looks nastier than it really is and hardly ever bothers a grown tree. Thin out the canopy so air moves through, keep the tree healthy, and only reach for sulfur or horticultural oil when a young tree takes a real beating.
Fix:
- Improve air circulation
- Maintain plant vigor
- Apply myclobutanil, propiconazole, sulfur, or horticultural oil if severe
Yellow spots up top with a bronzy sheen to the leaves
Flip a speckled leaf over and you'll spot the sycamore lace bug, a little lacy-winged insect that feeds on the underside and leaves dark specks and pale flecks up top. It looks worse than it acts and rarely sets back a healthy tree. Let the predators handle small numbers, hose off light bunches with a spray of water, and only bring in insecticidal soap if the bugs really pile up.
Fix:
- Encourage natural predators
- Wash off light infestations with a water spray
- Use insecticidal soap or imidacloprid when necessary
Toxicity
Good news if you've got pets in the house: the American sycamore is non-toxic to cats, dogs, and horses, and nothing about it will poison wildlife or livestock either. There's one catch, and it's mechanical rather than chemical. The fine hairs that shed from spring leaves and buttonballs can irritate eyes, skin, and lungs, so cover up when you rake or prune at leaf-out.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA marks this tree as non-toxic to cats, so a curious nibble isn't going to poison yours. You don't need to fuss over it here.
Dogs None
A dog can chew the leaves or bat a fallen seed ball around without any poisoning risk. If one gulps down plant matter and gets a little queasy, that passes on its own.
Horses None
Horses are fine around this tree, which the ASPCA clears for them too. Grazing nearby brings no toxic worry.
Rabbits Safe
Neither the leaves nor the bark hold anything poisonous to rabbits. Like any new green though, bring it in slowly so their stomach stays happy.
Livestock Safe
Cattle, goats, and sheep can browse the leaves without harm, since the tree carries no toxic principles.
Birds Safe
Birds nest, perch, and pick at the seed heads with no trouble at all. Those buttonballs are a familiar winter snack and pose zero danger.
People Safe
There's nothing poisonous about eating or handling this tree. The one genuine nuisance is mechanical: the fine hairs that shed from new spring leaves and buttonballs can irritate eyes, skin, and lungs, so put on eye protection and a dust mask when you rake or prune at leaf-out.
Not poisonous, but the fine hairs (trichomes) shed from emerging leaves and from the buttonball seed heads can mechanically irritate the eyes, skin, and respiratory tract of people during spring leaf-out; wear eye protection and a dust mask when raking or pruning at that time.
Varieties
True American sycamore is just one species, but its run-ins with anthracnose nudged nurseries toward the London planetree and its tougher selections. Here are the names you'll bump into most.
London planetree (Platanus × acerifolia / × hispanica)
Crossing American sycamore with Oriental plane gives you a tree that handles sycamore anthracnose much better than the native one, and that's exactly why cities reach for it so often.
'Bloodgood'
This London planetree selection is the one extension sources call out for its resistance to anthracnose.
'Liberty'
Here's another London planetree cultivar, and this one's said to shrug off both anthracnose and powdery mildew.
How to propagate
You can start a sycamore from seed or from a cutting, and one of those routes is a whole lot easier than the other.
SeedEasy
Sow in fall after seed balls disperse · Seedlings can grow 36 to 48 inches the first year under good light
Seed is the easy way to go here. Sow in fall once the buttonballs fall apart, and don't bother with any pretreatment, because the seed actually needs direct light hitting the soil surface to sprout. Give it that light and a seedling can put on 3 to 4 feet (90 to 120 cm) in its very first year.
Stem cuttingsModerate
Hardwood cuttings in late winter/dormancy; softwood during active growth · Several weeks to root, then one or more seasons to establish
Cuttings can work too, but only if you pick the right wood. Take hardwood cuttings in late winter while the tree's asleep, or softwood during active growth, and always grab them from young, fast-growing stems, because wood off an old tree just won't root by normal methods. Plan on several weeks for roots to show and a season or more before the young tree is really established.
Myths
American sycamore is toxic to your dogs and cats.
The ASPCA gives this tree a pass for cats, dogs, and horses, so a pet that chews a leaf or a seed ball isn't getting poisoned. The only real irritation is mechanical, not toxic. The fine hairs that drop from spring leaves and buttonballs can scratch at skin and airways, and honestly that bugs people a lot more than it bothers animals.
American sycamore and London planetree are basically the very same tree.
They look alike and share a genus, sure, but London planetree is a hybrid of American sycamore and Oriental plane, not the native species itself. The hybrid resists sycamore anthracnose far better, which is the big reason it's mostly taken over true sycamore along streets.