Ulmus americana (American Elm)

Handsome and graceful, Ulmus americana (American Elm) is a medium to large deciduous tree of upright-spreading habit, forming a very broad, flat-topped or vaselike crown. A fast grower, American Elm is a very impressive tree that has been widely planted as a street and lawn tree. However, many American Elms have been ravaged by the Dutch Elm disease and this species is no longer recommended for landscape uses. Considerable effort has been made to breed hybrids that are resistant to the Dutch elm disease.

Ulmus americana: An In-depth Look

Native: Native to eastern and central North America, it naturally occurs in forests, floodplains, and fields from the Great Plains eastward to the Atlantic Coast.

Plant Type and Habit: It is a large, fast-growing tree with a distinctive vase-shaped, spreading canopy. Its branching habit forms a high, overarching crown, making it a popular street and landscape tree.

Size: The American Elm can grow to significant sizes, typically reaching 60-80 feet in height (18-24 meters), with a spread of up to 40-70 feet (12-21 meters) at maturity.

Flowers: Small, inconspicuous reddish-green flowers appear before the leaves in early spring. They are followed by small, flat, winged seeds (samaras) that mature in spring and are dispersed by the wind.

Foliage: The foliage of leathery, dark green leaves, 3-6 inches long (7-15 cm), turns butter-yellow to rich yellow in the fall

Bark: The bark is gray-brown, deeply furrowed, and has a distinctive diamond pattern.

Uses: Historically popular as a street and shade tree due to its rapid growth and tolerant nature. Also used in woodworking and furniture making.

Hardiness: It is hardy in USDA zones 2-9.

Wildlife: Provides habitat and food for a variety of wildlife, including birds and squirrels.

Toxicity: There is no significant toxicity known for this species.

Deer and Rabbit: Young trees may be susceptible to browsing by deer and rabbits.

Drought Tolerance: Moderately tolerant to drought, especially when established.

Invasiveness: Not considered invasive; however, it can self-seed under favorable conditions.

Benefits: Offers significant ecological benefits, including carbon sequestration, habitat provision, and improving air quality.

Key Facts: The American Elm was severely affected by Dutch Elm Disease, a fungal disease spread by bark beetles, which drastically reduced its population. Resistant cultivars and hybrids have been developed to combat this disease. Among the most resistant selections are ‘Valley Forge’, ‘New Harmony’, ‘Creole Queen’, ‘Jefferson’, Prairie Expedition™ and ‘Princeton’.

American Elm Growing Tips

Light: Prefers full sun to light shade.

Soil: Adaptable to a wide range of soil types and soil conditions, including wet and dry sites. Prefers rich, well-drained, moist soils with a neutral to slightly acidic pH.

Water: Requires regular watering, especially during dry spells. Mature trees have moderate drought tolerance.

Fertilizer: Apply a balanced, slow-release fertilizer in early spring to promote healthy growth. Avoid over-fertilization, which can increase susceptibility to diseases.

Pruning: Prune in late winter to early spring to remove dead or diseased branches and maintain shape. Avoid excessive pruning, which can stress the tree.

Propagation: Typically propagated through seeds or grafting.

Pests/Diseases: Monitor for signs of Dutch Elm Disease, phloem necrosis, and wetwood. Rot, canker, and leaf spot may also occur. Pest visitors include borers, leafminers, beetles, mealybugs, caterpillars, and scale insects.