Alnus rubra

Common Names

Red Alder, Oregon Alder, Western Alder, Pacific Coast Alder, Californian Red Alder, Tag Alder

Summary

Red Alder (Alnus rubra) is a fast-growing, deciduous broadleaf tree native to the western North American Pacific Coast from Alaska to California, it typically reaches about 60 to 120 feet tall with a broad crown and smooth gray bark that turns reddish inner bark when exposed, leaves are oval to broadly elliptical, 6 to 15 cm long with coarse teeth and margins rolled under, it bears long pendulous male catkins and cone-like female fruits, and fixes atmospheric nitrogen through a Frankia association, enabling growth in moist soils and boosting soil fertility in woodland stands, in cultivation, it tolerates moist, well-drained soils and a wide range of substrates, including floodplains, streamsides, and even saline conditions, with a preference for full sun to partial shade and high water needs, especially when young, it is a pioneer, shade-intolerant species that rapidly colonizes disturbed sites and is valued for erosion control and riparian restoration, wood is used for furniture, cabinetry, doors, paneling, and other products, and the tree supports wildlife by providing habitat and forage, it can be propagated by seed in a seedbed and by various cuttings, depending on management goals

Lifecycle

Perennial

Height

600-1200 inches

Spread

15-26 feet

Hardiness Zones

Zones 5–10

Sunlight Requirements

Ideally full sun; tolerates partial shade for several years before requiring full sun for normal development.

Soil Type

Moist, well-drained soil; adaptable to sandy, loamy, and clay textures (deep loams or sandy loams).

Soil Drainage

No single ideal drainage; tolerates a wide range from well-drained gravels or sands to poorly drained clays or organic soils.

Soil pH

6.0-7.0, Slightly acidic to neutral soil pH, Tolerates all pH levels

Bloom Color

Yellow

Bloom Time

Spring

Foliage Color

Green, Yellow in fall

Fall Foliage Color

No distinct fall foliage color.

Leaf Lifecycle

Deciduous

Growth Rate

Fast-growing; rapid early growth, often over 1 meter in the first season, typically about 1 meter per year in early growth, and capable of more than 6 feet per year on good sites (60–80 feet in 20 years).

Seasons of Interest

Spring, Summer, Fall, and Winter.

Propagation Methods

Seeds, Cuttings

Attracts Wildlife

Attracts birds and butterflies