# Alder (Alnus glutinosa)

> A conical to rounded tree of around 28 m with sticky young leaves, dark woody cones and roots that fix nitrogen with the bacterium Frankia. It is the tree for riverbanks, ponds and waterlogged corners where little else will grow, stabilising banks and sheltering otters, siskins and redpolls. Widely planted in riparian restoration and flood-mitigation schemes.

Source: https://treerm.org/trees/alnus-glutinosa · Updated 2026-11-08 · License CC BY 4.0

## Facts

- Also called: Common alder, Black alder
- Family: Betulaceae
- Type: Broadleaf, drops leaves
- Mature height: 25 m; spread 10 m
- Growth: Fast growing; lives about 60 years
- USDA hardiness zones: 3 to 7
- Light: Full sun
- Water: Likes water
- Soil: Wet, poorly drained or periodically flooded soils; also grows on drier ground
- Native range: Native across Europe including Britain and Ireland, to North Africa, Türkiye, the Caucasus, Iran and western Siberia.

**Benefits:** Fixes nitrogen, Holds soil, Flood tolerant, Wildlife, Birds, Fast canopy, Pollinators

**Good for:** Streambanks, Reforestation, Windbreak, parks

**Watch out for:** Short lived, Pest prone

## Care

Plant in winter straight into damp ground; no staking needed and it tolerates having its feet in water. Prune in late summer if required. The main threat is Phytophthora alder disease (root rot, bleeding bark lesions, small yellow leaves); avoid moving soil or plants from affected sites. Roughly 60-year lifespan.

## Where it stands

- **Native:** Germany; France; United Kingdom; Ireland; Sweden
- **Adapted:** TAS, Australia (Introduced per WCVP); New Zealand (Introduced and naturalised; listed as a weed by Weedbusters NZ)

## Sources

- https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/a-z-of-british-trees/alder/
- https://www.gbif.org/species/2876213
- https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=277813