Alnus incana - Grey Alder

Native to Europe and the Caucasus, the Grey Alder was introduced to Britain around 200 years ago. A fast growing deciduous tree, it does well even on very dry soils, is often used to reclaim derelict land and spoil heaps, and in the wild it can be found in habitats as diverse as rocky mountain slopes and boggy riversides. The smooth, dark grey bark makes it an attractive choice for planting.

Site and soil

Although tolerant of a wide range of soils, the Grey Alder is especially good on dry, infertile soils where little else will grow. It does, however, need good light to do well.

Height and spread

Below are the approximate stages of growth, assuming sited in suitable conditions for this species;

After 10 years: 9m x 6m
After 20 years: 20m x 10m

Leaf and bark

The leaves are ovate and sharply pointed, dark green and shiny, grey beneath and densely hairy. The bark is a distinctive smooth dark grey.

Flower, seed and fruit

Clusters of 3 or 4 yellow-brown catkins appear in late February, developing into hard green fruits in summer. The woody ‘cones’ remain on the tree over winter.

Uses

Alder makes an attractive specimen tree and can be used for windbreaks, hedging and screening. It plays an important role in the reclamation of derelict land.

Wildlife

The catkins of Grey Alder are an early source of pollen for insects, and the ‘cones’ provide food for birds in winter. Its ability to grow well on the poorest of soils – even on spoil heaps – where the nitrogen-fixing nodules on its roots improve the fertility of the soil, makes it invaluable for reclaiming derelict land.