Populus balsamifera ssp. trichocarpa, black cottonwood
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Broadleaf Deciduous Trees

Populus balsamifera ssp. trichocarpa

black cottonwood

Salicaceae

Western North America, from Alaska to California

At a Glance

TypeTree
HabitUpright
FoliageDeciduous
Height80-150 feet (24-46 m)
Width30-60 feet (9-18 m)
Maturity20 years

Growing Zones

USDA Hardiness Zones

3 - 9
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
Zone 8
Zone 9
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Key Features

Fragrant (strong)
Native to North America
Maintenancehigh

Overview

Populus balsamifera ssp. trichocarpa is the largest native broadleaf tree in western North America, reaching 80-150 feet (24-46 m) tall with a spread of 30-60 feet (9-18 m) in favorable conditions. Crown is narrowly conical in youth, becoming broadly columnar to open and irregular with age. Trunk is straight, reaching 3-5 feet (0.9-1.5 m) in diameter on mature specimens, with smooth, yellowish-gray bark on young trees that becomes thick, deeply furrowed, and dark gray-brown with age. Leaves are alternate, simple, broadly ovate to deltoid, 3-6 inches (8-15 cm) long, glossy dark green above and silvery-white beneath, creating a two-toned shimmer in wind. Leaf buds and emerging foliage are heavily resinous, releasing a strong balsam fragrance noticeable from considerable distance, particularly in spring. Dioecious; pendulous catkins appear in March to April before leaves. Female trees produce cottony seeds in May to June that disperse widely by wind and water. Growth rate is very fast at 36-60 inches (91-152 cm) per year in moist conditions, among the fastest of any North American tree. Individual trunks are relatively short-lived at 100-200 years, though root systems resprout. Wood is soft, weak, and brittle; limb breakage in storms is frequent. Root systems are extensive, aggressive, and shallow, invading sewer lines, drainage systems, and foundations. Not suitable for residential landscapes or confined urban spaces due to size, aggressive roots, brittle wood, and cottonseed litter.

Native Range

Native to western North America from southern Alaska south through British Columbia, Washington, Oregon, and California, east to western Montana and Idaho. Occurs predominantly along rivers, streams, floodplains, and moist bottomlands from sea level to 7,500 feet (2,300 m). The dominant riparian tree throughout the Pacific Northwest lowlands.

Suggested Uses

Used primarily in riparian restoration, streambank stabilization, and large-scale ecological plantings. Establishes rapidly from hardwood cuttings or live stakes inserted directly into moist soil. Functions as a nurse crop for slower-growing conifers in reforestation projects. Not suitable for residential landscapes, parks, or urban forestry due to size, aggressive roots, brittle wood, and cottonseed litter from female trees.

How to Identify

Identified by glossy dark green leaves with silvery-white undersides, heavily resinous and fragrant leaf buds, and straight trunk with deeply furrowed dark bark on mature trees. Leaves are broadly ovate, 3-6 inches (8-15 cm) long, with fine crenate-serrate margins. Distinguished from Populus tremuloides by larger leaves, non-flattened petioles, and darker bark. Distinguished from Populus nigra by broader leaves and native range.

Appearance

Size & Dimensions

Height80' - 150'
Width/Spread30' - 60'

Reaches mature size in approximately 20 years

Colors

Flower Colors

red
green

Foliage Colors

green

Fall Foliage Colors

yellow

Bloom Information

Bloom Period

~2 weeks
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Spring
Pendulous catkins appear in March to April before leaf emergence. Male catkins are reddish, 2-3 inches (5-8 cm) long. Female catkins are green, elongating to 4-8 inches (10-20 cm) as capsules develop. Cottony seeds disperse in May to June over a 2-3 week period, traveling considerable distances by wind and water. Only female trees produce cotton; male clones can be selected to avoid this litter.

Detailed Descriptions

Flower Description

Reddish (male catkins), green (female catkins)

Foliage Description

Glossy dark green above, silvery-white beneath

Growing Conditions

Sun Requirements

Full Sun
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

Soil Requirements

pH Range5.0 - 8.0(Neutral)
357912
Soil Types
loamclaysandsilt
Drainage
moist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

5-10 years

Care & Maintenance

Care Guide

Established trees require no supplemental care. New plantings establish rapidly with consistent moisture during the first growing season. Grows in full sun; intolerant of shade. Thrives in moist to wet soils, including seasonally flooded sites. Tolerates a wide range of soil types. Not recommended for residential landscapes, gardens, or areas near infrastructure due to aggressive root systems that invade sewer lines and foundations, brittle wood prone to storm breakage, and prolific cottonseed litter from female trees. Primary use is in riparian restoration and large-scale ecological plantings. Susceptible to poplar borer, tent caterpillars, and various leaf rust and canker diseases, though established trees typically tolerate these without intervention.

Pruning

Pruning is not practical or necessary in ecological restoration plantings. In managed landscapes, remove hazardous dead or broken limbs as needed. Prune in late winter (January through February) while dormant. Brittle wood and fast growth produce frequent storm-damaged branches requiring cleanup. Avoid topping, which produces weak, fast-growing water sprouts more prone to failure.

Pruning Schedule

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winter

Maintenance Level

high

⚠️ Toxicity Warning

Non-toxic
Populus balsamifera ssp. trichocarpa (black cottonwood) - Identification & Care Guide | PlantRef