Populus trichocarpa

Common Names

Black Cottonwood, California Poplar, Western Balsam Poplar, Balsam Poplar, Balsam Cottonwood, Common Black Cottonwood

Summary

Black cottonwood is a fast-growing, large deciduous tree native to western North America, extending from Alaska to Baja California and commonly found along moist alluvial riparian zones where extensive stands form. It reaches heights of roughly 30–60 meters with a broad crown and gray-brown, deeply furrowed bark; leaves are simple, broadly ovate with glossy dark green uppersides and pale undersides, and winter buds are resinous with a balsamic scent. The species is dioecious, with separate male and female catkins; seeds are numerous and dispersed by wind and water, wrapped in cottony hairs, producing the familiar cottony seed fluff. It is a pioneer that tolerates flood-prone, moist soils and features an aggressive root system that helps stabilize soils and can form hybrids with other poplars.

Cultivation favors full sun and moist, well-drained soils, though it tolerates wet to moderately dry sites and is hardy to USDA zones 5A–8B. Propagation is possible from seeds sown soon after ripening or from stem cuttings, and planting only male trees is advised to reduce spring cottony seed release. The tree has an aggressive root system that can invade drainage systems and foundations, so planting should be in spacious locations. Uses include shade, windbreaks, riparian restoration, erosion control, wildlife habitat, and timber/pulp products such as particle board, plywood, veneer, and lumber; resin from buds has historical medicinal uses, and the tree supports biodiversity along waterways.

Lifecycle

Perennial

Height

98.5-197 feet

Spread

6-6.5 feet

Hardiness Zones

Zones 5-8

Sunlight Requirements

Ideally full Sun; tolerates partial shade.

Soil Type

Deep, moist alluvial soils with abundant moisture, nutrients, and near-neutral pH (about 6.0–7.0)

Soil Drainage

Moist, well-drained soils.

Soil pH

6.0-7.0 (nearly neutral), Acidic to neutral soil

Bloom Color

Greenish-yellow, greenish, pale yellow, red, reddish-purple

Bloom Time

Spring (March–June).

Foliage Color

Dark green on the upper surface with a pale underside.

Fall Foliage Color

Yellow

Leaf Lifecycle

Deciduous

Growth Rate

Very fast-growing, height growth often exceeding 5 feet per year for at least the first 10 years, and can reach about 50 feet (15 m) in as little as 10 years

Seasons of Interest

Spring, Summer, and Fall

Propagation Methods

Seeds, Cuttings, Layering-like vegetative propagation

Attracts Wildlife

Attracts birds, attracts butterflies