Ulmus pumila
Siberian elm
Overview
Ulmus pumila is a fast-growing deciduous tree reaching 50-70 feet (15-21 m) tall with an open, rounded crown of similar spread. The small, elliptical leaves are 0.75-3 inches (2-7.5 cm) long, smooth, and singly toothed, with a nearly symmetrical base that separates it from native elms. Clusters of small greenish flowers open in early spring before the leaves, followed by flat, round, winged seeds (samaras) about 0.5 inch (1.3 cm) wide that ripen and scatter in large numbers by late spring. Native to eastern Siberia, Mongolia, northern China, and Korea, U. pumila was widely planted in North America for fast shade and shelterbelts because it tolerates cold, heat, drought, wind, and poor soil. It has since naturalized and is listed as invasive across much of the United States, seeding aggressively into disturbed ground. The wood is brittle and prone to storm breakage, and the tree is susceptible to elm leaf beetle and to cankers, though it resists Dutch elm disease better than the American elm. It is hardy to USDA zone 4.
Native Range
Native to eastern Siberia, Mongolia, northern China, the Russian Far East, and Korea. Introduced to North America in the early 20th century and now naturalized and invasive across much of the United States.Suggested Uses
Used for fast shade, windbreaks, and shelterbelts on harsh, dry sites, though its weak wood and invasive seeding limit where it is planted. Spaced 30-40 feet (9-12 m) apart when used as a screen.How to Identify
Appearance
Size & Dimensions
Height50' - 70'
Width/Spread40' - 60'
Reaches mature size in approximately 15 years
Bloom Information
Small greenish, petal-less flowers open in early spring, in March or April, before the leaves. They are wind-pollinated and inconspicuous. Within weeks they give way to round winged seeds that ripen and drop in great numbers by late spring.
Detailed Descriptions
Foliage Description
GreenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Ulmus pumila grows in full sun and tolerates a wide range of soils and pH from 5.5 to 8.0, along with cold, heat, drought, wind, and compacted urban ground. It needs no irrigation once established and grows rapidly. The tree is hardy to USDA zone 4. Its weak wood breaks readily in storms, and abundant self-sown seedlings can colonize nearby ground, so removing seedlings limits its spread. Elm leaf beetle, cankers, and aphids are common problems. No fertilizer is needed.Pruning
Prune in late winter to remove weak, narrow crotches and crossing limbs that are prone to splitting. Regular structural pruning of young trees reduces later storm damage. Remove dead and broken wood as it appears.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
winter