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Alnus glutinosa

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© RHS 2002

Characteristics

Plant type

Tree

Habit

Columnar/Upright

Origin

Native to the UK

Resilience

Hardiness

old H4 (hardy)

Colour

Flower

Brown in Spring

Foliage

Green in Autumn, Spring and Summer

Fruit

Dark Brown in Autumn

Stem

Dark Brown in

Size

Ultimate height

Higher than 12 metres

Ultimate spread

4-8 metres

Time to ultimate height

20-50 years


Preferred common name

common alder

Family

Betulaceae


Alnus are vigorous deciduous trees and large shrubs with rounded leaves and often conspicuous catkins in winter

A. glutinosa is a deciduous tree to 25m, broadly conical in habit when young, with grey-purple buds and young catkins conspicuous in winter, and rounded bright green leaves

Other common names

  • aar
  • aller
  • black alder
  • European alder

How to grow

Sunlight

  • Full sun

Aspect

  • South-facing, North-facing, West-facing or East-facing
  • Exposed or Sheltered

Cultivation

This genus noted for its ability to thrive in poor, wet conditions and is widely used in land reclamation

Soil

  • Moist but well-drained or Poorly-drained
  • Acid, Alkaline or Neutral
  • Loam, Chalk or Clay

Propagation

Propagate by seed or hardwood cuttings

Suggested planting locations and garden types

Low Maintenance, Wildflower meadow, Wildlife Gardens, Coastal or Hedging/Screens


How to care

Pruning

Pruning group 1

Pests

Can get alder sucker and leaf-mining sawflies

Diseases

Susceptible to Phytophthora