A grand, stately deciduous variety suited for large landscapes, the American sycamore tree (Platanus occidentalis) is a common sight across the United States.
As a member of the maple family, it is also known as the “buttonball,” “buttonwood,” or “American plane tree.”
Depending on species, sycamore trees grow in USDA plant hardiness zones 4 to 10. They thrive under full sun or in light shade, in areas with well-draining soil.
But did you know the USA is also home to a few hybrid varieties of this tree, native to the Middle East?
Identifying the Plane Tree in the United States
One of the top choices for its shade and wide foliage, sycamores are a common sight in parks, along water bodies, and throughout other open spaces.
A mature sycamore tree can grow between 75 – 100 feet in height, and 50 – 70 feet in width, with its trunk growing to around 7 feet in diameter.
You can easily identify an American sycamore tree (Platanus occidentalis) by the following characteristics:
- The camouflage pattern of its bark — It has a gray-brown outer layer, and the top peels off in patches to reveal the underlying light gray or white wood. The bark color in mature sycamore trees varies between brown and light gray.
- Distinctive palmate leaves — With serrated edges that turn dark green on maturity and small white hairs on the underside, these leaves bear a close resemblance to maple leaves. After shedding, they turn spectacular shades of gold, yellow, and red.
- The singular, ball-like fruits — Another characteristic feature, these hang from thin stalks. Each dry, hairy fruit is about 1 inch in diameter and contains seeds.
Germinating and Transplanting a Sycamore
Sycamore trees can grow to massive sizes and live as long as 400 years. They are a fast-growing species that gain roughly 2 feet annually and have a complex system of roots.
Growing a sycamore from the seed ball stage involves the following steps:
- Procure good quality sycamore balls from a nursery or garden center. You can also collect seed pods from a healthy tree in autumn.
- Dry the seed balls and cool them at a minimum of 40°C (104°F) for about 12 weeks.
- Crack the dried seed balls open, extract the seeds, and clean them properly
- Prepare germination trays with moist, highly acidic soil of a pH between 4.5 – 5. Ensure the soil contains a high percentage of organic materials, like peat moss and mulch.
- Place the seeds on damp blotting paper at room temperature and allow them two weeks to sprout.
- Transfer them to the germination trays and plant them 6 to 8 inches apart.
- Keep the trays away from direct sunlight for a month and water them regularly to prevent the soil from drying up.
- Once the seedlings grow to about 4 inches tall, transfer them to pots. Place porous material like gravel and sand at the bottom of the pots to help drain excess water.
- When the seedlings have grown to a height of about 1 foot, they are ready to be planted outside.
Things to Keep in Mind With Your Sycamore Tree
When transplanting the sycamore tree, make sure you choose a spot in the yard with about 12 feet of space on all sides — this allows enough room for the complex root system to develop.
The primary roots extend only 30 inches or so into the ground, while the rest of it spreads out laterally.
Sycamore roots are sturdy and known to cause cracks through concrete sidewalks, water pipelines, building foundations, and so on, which is why the American sycamore lost its popularity as a street tree.
Giving them ample room to grow is crucial for tree health.
Being deciduous trees, sycamores shed their leaves, and — while they add to the beauty of the brilliant fall color — this tends to create litter that needs cleaning.
The leaf debris doubles up as a breeding space for fungus and bacteria, and this can cause diseases in the American sycamore itself.
Protecting Your Sycamore Tree From Weather Damage
A mature American sycamore tree can handle the harshest of weather conditions, including snow and freezing cold. The young ones, however, are not so resilient — especially if they’ve been grown in a nursery under ideal conditions.
Young American sycamore trees are highly unlikely to survive temperatures lower than -36°C. It is essential to prepare them well to make it through rough weather.
You can spread a 2-inch layer of mulch around the trunk base once the weather starts turning chilly, which adds moisture and nutrients to the soil and acts as a pest deterrent. You can also cover young sycamores in burlap to protect against the cold.
Pruning and Maintaining a Sycamore Tree
Sycamore trees can grow in odd shapes as they mature. This includes multiple trunks and branches that spread out in all directions, sometimes wrapping around the parent tree — and often drooping and jutting out at odd angles.
Regular pruning becomes necessary for an American sycamore as the tree ages, to give it a good shape and promote overall growth. June is generally a good time to prune a sycamore without any adverse effects. You must also remove deadwood periodically.
Sycamore trees — especially ones growing in a public place or a yard — also benefit from crown pollarding. This not only shapes the canopy well but helps maintain the street trees at the optimum height. Pollarding very large trees allows them better access to sunlight and air.
On top of this, newly planted sycamore saplings need fertilizers to ensure optimum nutrition and growth. You can fertilize the soil anywhere between one to four times a year, depending on the type of fertilizer — granular, liquid, or stake type fertilizers are the three more common varieties.
Common Sycamore Tree Diseases and Remedies
The sycamore tree is among the more resilient species found in North America. However, it is not impervious to disease.
Let’s take a look at some of the most common problems these sturdy shade trees face.
A fungal disease caused by the Apiognomonia venata, anthracnose is the most serious affliction of sycamore trees.
It is characterized by black fungal growths that affect the twigs, branches, and leaves. Severe infection can lead to premature defoliation multiple times in a single season.
The fungal spores thrive amid leaf debris, making regular cleaning essential. You must also prune the affected parts of the trees to arrest the spread.
Take care to disinfect your equipment to prevent healthy trees from getting contaminated.
Spraying a natural fungicide like neem oil helps prevent and control the spread of the sycamore anthracnose disease. The best preventive measure, however, is to plant resistant cultivars.
Another fungal infection caused by the Microsphaera fungus, powdery mildew manifests as white patches on the surface of leaves in late summer and autumn. The disease also distorts the shape of the sycamore leaves.
However, the affliction causes little damage to a sycamore tree other than deforming the leaves and causing premature shedding. Any fungicide that helps control anthracnose is equally good at controlling powdery mildew.
Bacterial Leaf Scorch (BLS)
Caused by a bacterial pathogen called Xylella fastidiosa, this disease affects not just sycamore trees but a variety of other shade trees — including maples, oaks, and dogwoods.
The bacteria lives in the xylem or water-carrying tubes of a plant, and insects that feed on the xylem fluid from infected plants act as the carriers of the disease. It can also be transferred between trees via root grafts.
Irregularly scorched portions on matured leaves are the most prominent symptom of BLS in sycamores. The disease progresses slowly, from the mature leaves to the younger ones. Over the years, it can lead to the decay of entire branches, eventually causing infected trees to perish.
While there is no prevention against BLS, early detection and thorough pruning has proven to be a moderately successful cure. Proper irrigation, fertilization, and mulch treatment also help provide nutrients that fortify the immune system of sycamore trees.
Canker stains is a lethal fungal affliction of the sycamore tree, caused by the Ceratocystis fimbriata. Its symptoms include reduced foliage, stunted leaf growth, and the appearance of elongated, sunken cankers on the trunk and older branches.
The fungus is transferred from tree to tree by insects that feed on the sap. However, the most severe infections are traced back to contamination from wounds caused during pruning and other tree maintenance work.
Although the infection progresses slowly, canker stains have no cure. Once a sycamore tree is infected, the only option is to remove and destroy it.
Learn More About Tree Care
Taking proper care to plant a sycamore tree, and looking after it in its early days, goes a long way in growing a healthy tree that will thrive for years. Read our blogs on overall tree care to get it right on your very first attempt.