About
Alnus sieboldiana is a medium-sized deciduous tree or shrub that typically reaches heights of up to 12 meters. Its foliage consists of green leaves with lighter undersides, featuring serrated margins and prominent veins. The male catkins are robust and yellow, while the female reproductive structures resemble woody cones, measuring 2-3 centimeters in length, and are found individually during the autumn and winter months.
About the genus
Alnus comprises robust deciduous trees and sizable shrubs characterized by their rounded foliage and, during winter, noticeable catkins.
Growing conditions
- Sunlight
- Full sun
- Soil type
- Clay, Loam
- Soil pH
- Acid, Alkaline, Neutral
- Soil moisture
- Poorly-drained
- Aspect
- East-facing, North-facing, South-facing, West-facing
- Exposure
- Exposed, Sheltered
- UK hardiness
- H7
Plant details
- Plant type
- Trees
- Habit
- Spreading branched
- Foliage
- Deciduous
- Height
- 8-12 metres
- Spread
- 4-8 metres
- Time to full height
- 10-20 years
- Suggested uses
- Architectural
- Native to
- Japan
Care notes
- 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.
- Pruning
- Pruning group 1
- Propagation
- Propagate by hardwood cuttings or seed. For more advice see our information on how to propagate from seed (tree/shrub
- Pest resistance
- May be susceptible to alder leaf beetle, alder sucker and leaf-mining sawflies
- Disease resistance
- May be susceptible to phytophthora root rot and honey fungus