Mountain Alder vs Red Alder - TreeTime.ca

Mountain Alder vs Red Alder

Alnus incana subsp. tenuifolia

Alnus rubra

CUSTOM GROW

CUSTOM GROW

Mountain Alder
Red Alder

Mountain Alder is a native cold-hardy shrub or small tree often found along streams and in moist forested habitats. Its nitrogen-fixing ability enriches soils and supports surrounding vegetation, while its extensive root system helps stabilize streambanks and slopes. The fast growth rate allows it to establish quickly on disturbed sites, making it especially valuable in reclamation, restoration, and erosion control projects.

Often forming dense thickets, Mountain Alder enhances habitat quality in riparian and upland areas. It provides food and cover for various wildlife, including birds and small mammals. Recognized as an important species for soil and water conservation, it is well suited for riparian planting, naturalization, and ecological restoration.

Note: We use Sitka Alder for Alnus incana subsp. tenuifolia. This species is also known by many other common names, including Grey Alder, River Alder, and others. Please confirm the scientific name to ensure you are ordering the correct plant.

Red Alder is a fast-growing deciduous tree native to western North America. Its fixes nitrogen, which enriches soils and supports the growth of surrounding plants. Ideal for sites with poor soil conditions, or areas disturbed by logging, construction or fire.

It provides shade in riparian areas, creating cover for fish. Its seeds and buds are eaten by birds and small mammals, while the foliage provides browse for wildlife. The catkins release clouds of pollen attracting bees and other insects.

The Red Alder gets its namesake from the rusty-red color the bark turns when bruised.

Mountain Alder Quick Facts

Red Alder Quick Facts

Zone: 1a
Zone: 5b
Height: 6 m (20 ft)
Height: 15 m (50 ft)
Spread: 3 m (10 ft)
Spread: 9 m (30 ft)
Light: partial shade, full sun
Light: partial shade, full sun
Moisture: normal, wet
Moisture: normal, wet
Growth rate: medium
Growth rate: fast
Life span: medium
Life span: medium
Growth form: multi-stemmed, thicket-forming
Growth form: upright, rounded to conical
Spreading: rhizomes - medium, seeds - low, layering - low
Spreading: seeds - medium, stump sprouting - medium


Bark: smooth, gray to brown
Bark: smooth, grey
Hybrid: no
Hybrid: no
Catkins: yes
Catkins: yes


Native to: AB, BC, SK, YT, NT
Native to: BC
Other Names: river alder, speckled alder, thin-leaved alder, thinleaf alder, western river alder
Other Names: oregon alder, pacific coast alder, western alder