Betula occidentalis
Common Name: water birch 
Type: Tree
Family: Betulaceae
Native Range: Western North America
Zone: 4 to 6
Height: 10.00 to 40.00 feet
Spread: 10.00 to 30.00 feet
Bloom Time: April to May
Bloom Description: Brown (male) and green (female)
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Low
Suggested Use: Hedge
Flower: Showy
Tolerate: Deer, Clay Soil, Wet Soil

Culture

Best grown in acidic, moist to wet soils in full sun to part shade. Best in moist fertile soils. Consider using soaker hoses and bark mulches to keep the root zones cool and moist. Little pruning is needed, but if necessary, prune during the dormant season. Avoid pruning in spring when the sap is running because bleeding will occur. Tolerates flooding. Best growth occurs in USDA Zones 4-6.

Noteworthy Characteristics

Betula occidentalis, commonly known as water birch, is a shrubby tree of riparian woodlands that is most commonly found growing in clumps or thickets along rivers, streams, springs or other water courses in elevations to 8000’ from the Cascades, forested areas of Western Canada, and the Canadian Rockies south through the U.S. Rockies to New Mexico. It is often seen growing as a single to multi-stemmed shrub to 10-15’ tall, but sometimes rises to as much as 40-50’ tall as a multi-trunked tree with a broad, irregular, open crown.

Non-peeling bark is shiny, reddish-brown and marked with white horizontal streaks. Alternate, deciduous, broad-ovate leaves (each to 1-3” long) have rounded to wedge-shaped bases, blunt to sharp-pointed tips, 4-5 pairs of side veins and a double row of fine, sharp-pointed marginal teeth. Leaves are dark greenish yellow and shiny above, but paler and gland-dotted beneath.

Male and female flowers bloom in separate catkins on same plant in spring. The drooping brownish male catkins are larger (to 2.5” long) than the smaller more upright female catkins Fruiting cones (to 1.2” long) appear in late summer. Each cone containing numerous 3-lobed scales, with each scale enclosing a tiny winged seed.

This plant serves in the wild as a source for food and lodging materials for beavers.

Genus name is the Latin name for birch.

Specific epithet means western in probable reference to its western U.S. native origin.

Problems

Birch leaf miner and aphids are potential insect problems. Weakened birches become vulnerable to the bronze birch borer which can infect and kill trees, particularly those that are stressed by summer heat and humidity. Plants stressed by insects seem more susceptible to cankers. Watch for leaf spot diseases. Iron chlorosis may occur in high pH soils. Susceptible to honey fungus.

Garden Uses

Water birch is most frequently grown within the geographic area of its native range. It is particularly effective when planted in small groups in consistently moist to wet soils along ponds, streams or in low spots.