Alnus formosana
A fast-growing deciduous tree to 20m. Leaves are green with an elongated shape, pink when young then shiny green until they fall in autumn. Male catkins hang in large numbers in spring and female woody 'cones' persist on the branches through the winter
Size
Ultimate height
Higher than 12 metresTime to ultimate height
20–50 yearsUltimate spread
Wider than 8 metresGrowing conditions
Moisture
Poorly–drainedpH
Acid, Alkaline, NeutralColour & scent
| Stem | Flower | Foliage | Fruit | |
| Spring | Cream | Green Pink | ||
|---|---|---|---|---|
| Summer | Green | |||
| Autumn | Green | Brown | ||
| Winter | Brown |
Position
- Full sun
Aspect
East–facing or North–facing or South–facing or West–facing
Exposure
Exposed or Sheltered Hardiness
H6Botanical details
- Family
- Betulaceae
- Native to GB / Ireland
- No
- Foliage
- Deciduous
- Habit
- Spreading branched, Columnar upright
- Genus
Alnus are vigorous deciduous trees and large shrubs with rounded leaves and often conspicuous catkins in winter
- Name status
Correct
- Plant range
- Taiwan
How to grow
Cultivation
It is a nitrogen-fixer so can grow on poor soil. Suited to river banks on permanently damp soil in good light. For more information see tree cultivation.
Propagation
Propagate by hardwood cuttings or seed. For more advice see our information on how to propagate from seed (tree/shrub
Suggested planting locations and garden types
- Architectural
- Banks and slopes
Pruning
Pests
May be susceptible to alder leaf beetle, alder sucker and leaf-mining sawflies
Diseases
May be susceptible to phytophthora root rot and honey fungus
Get involved
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.