Alnus incana

Common Names

Speckled Alder, Grey Alder, Thin-leaved Alder, Mountain Alder, Tag Alder, Hazel Alder, Hoary Alder

Summary

Grey Alder (Speckled Alder) is a fast-growing pioneer tree or shrub in the Betulaceae that forms dense wetland thickets via root suckering and layering. It tolerates wet soils and periodic flooding, typically occupying moist to wet sites along streams, ponds, and wetlands. Leaves are ovate to elliptic with doubly serrate margins, and catkins appear before leaves in early spring; the bark is light to dark gray, and the plant is nitrogen-fixing via root nodules, contributing to soil enrichment.

In cultivation, it prefers moist to wet soils and can tolerate flooding, with full sun to partial shade and hardiness in zones 2–6. It is fast-growing, coppices easily, and forms dense stands, making it suitable for erosion control, soil stabilization, and rehabilitation of disturbed sites; it propagates by seed or cuttings and offers wildlife habitat value.

Lifecycle

Perennial

Height

15-25 feet

Spread

15-25 feet

Hardiness Zones

Zones 2-6

Sunlight Requirements

Ideally full sun to partial shade.

Soil Type

Moist, loamy soil that is well-draining yet moisture-retentive, slightly acidic to neutral, rich in organic matter

Soil Drainage

Moist to wet, well-drained soils

Soil pH

6.5-7.2

Bloom Color

Red

Bloom Time

Late winter to early spring

Foliage Color

Green (often dark green on the upper surface and dull green/gray-green on the lower surface)

Fall Foliage Color

Little color change in fall

Leaf Lifecycle

Deciduous

Growth Rate

Fast-growing

Seasons of Interest

Spring, Summer, Fall, Winter

Propagation Methods

Seeds, Cuttings, Layering, Division, Root suckers, Runners, Coppice regeneration

Attracts Wildlife

Attracts birds, Attracts butterflies