American sycamore
Platanus occidentalis
also called sycamore, american planetree, buttonwood
The great white-boned tree of American river bottoms, its upper bark peeling to a smooth bone-and-cream patchwork that carries the garden through winter better than any flower.
- Type
- Tree · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Sunlight
- Full sun
- Watering
- Moderate to high
- Soil
- Deep, moist; a bottomland tree that takes ordinary garden soil
- Feeding
- All-purpose balanced
- USDA zones
- 4b–9a
- Frost tolerant
- Yes
- Plant out
- 14 days before the last spring frost
- Plant spacing
- 49 ft 3 in
- In-row spacing
- 39 ft 4 in
- Between rows
- 59 ft 1 in
- Square-foot density
- Not suited to SFG
- Root system
- Woody, shallow, wide and opportunistic
- Working depth
- 12–24 in
- Can reach
- 3.5 ft down where the soil allows
- Spread
- 207–276 ft across, about 3–4× the width of the plant
These roots go looking, and what they find is drains, soakaways, footings, paving and the border next door. Give it real distance from anything you would mind being lifted or blocked: the reach below ground is several times what the crown suggests.
A huge shallow root system that goes looking for water and reaches drains, foundations and septic fields. It is a magnificent tree for a river bank and a poor one for a small garden.
The habit is American sycamore’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- Cats and dogs
- Confirmed safe
We say a plant is safe only where a named poison-control reference names that exact species and records it as non-toxic to both cats and dogs. Most plants are on nobody’s list, and their absence here is not a judgement about them. This is a record of what those references say, not veterinary advice, and it cannot account for your own animal, the quantity eaten, or a plant treated with anything.
The ASPCA files our exact species under its own misspelling, as Plantanus Occidentalis, and records it Non-Toxic to Dogs, Non-Toxic to Cats and Non-Toxic to Horses. The Pet Poison Helpline carries no sycamore.
- When
- Not harvested. The one job is structural pruning while the tree is young, in winter.
- What to look for
- Crossing limbs, double leaders or a branch heading somewhere it cannot be allowed to go. On a tree this size, everything worth fixing is visible in the first ten years.
- How to harvest
- Take out crossing and competing limbs to one clean leader while cuts are still small. After that, put the pruning saw away and let it be enormous.
- How often
- A winter look for its first decade, then essentially never.
- Storing the crop
- Nothing to store. Rake the big leathery leaves off the lawn; they break down slowly, so shred them for mulch rather than piling them whole.
- Lace bugs Lace bugs stippling the leaves gray-white by late summer
- Bacterial leaf scorch Bacterial leaf scorch in aging street trees
- Powdery mildew Powdery mildew on late regrowth
- Sycamore anthracnose Sycamore anthracnose blighting the first flush of leaves in a cool wet spring; the tree shrugs and releafs by July
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Assassin bug ReduviidaeHunts Lace bugs
A patient ambusher with a curved beak it drives into whatever it catches — caterpillars, beetles, bugs, and the occasional bee, so count it a generalist rather than a specialist. It will jab a careless finger too, so admire it and leave it be.
- Green lacewing Chrysoperla carneaHunts Lace bugs
Its bristly larvae — "aphid lions" — impale aphids, mealybugs, thrips, and mite colonies, eating hundreds a week. Adults feed on nectar and pollen from small open flowers and overwinter in hollow stems left standing.
- Minute pirate bug Orius spp.Hunts Lace bugs
A pinhead-sized true bug that is the best natural check on thrips, and happily spears aphids, mites, and insect eggs too. It needs pollen when prey is scarce, so keep something flowering nearby.
Old sycamores go hollow while staying perfectly healthy, and the pioneers stabled pigs and sometimes themselves inside standing trees. Plant it only where a truly enormous tree is the point.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com