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AGM plants have been through a rigorous trial and assessment programme. They are:
This plant will provide nectar and pollen for bees and the many other types of pollinating insects.
It is included in an evolving list of plants carefully researched and chosen by RHS experts. Divided into 3 groups these lists, linked below, are maintained by a team of RHS staff and are reviewed annually.
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Other common names common alder aar
aller black alder European alder
Family Betulaceae
Genus Alnus are vigorous deciduous trees and large shrubs with rounded leaves and often conspicuous catkins in winter
Details 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
Plant range Europe to N Africa
Foliage Deciduous
Habit Columnar/Upright
Hardiness
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H7
Full Sun
Aspect East-facing or South-facing or North-facing or West-facing
Exposure Exposed or Sheltered
Chalk
Clay
Loam
MoistureMoist but well-drained, Poorly-drained
SoilChalk, Clay, Loam
pHAcid, Alkaline, Neutral
Ultimate height Higher than 12 metres
Ultimate spread 4-8 metres
Time to ultimate height 20-50 years
Cultivation This genus is noted for its ability to thrive in poor, wet conditions and is widely used in land reclamation
Propagation Propagate by seed or hardwood cuttings
Suggested planting locations and garden types Hedging & Screens Low Maintenance Coastal Wildflower meadow Wildlife Gardens
Pruning Pruning group 1
Pests Can get alder sucker and leaf-mining sawflies
Diseases Susceptible to Phytophthora
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