Japanese Alder
Alnus japonica
- Native to:
- China, Japan, Korea, Kuril Is., Russia, Taiwan
Source: Wikimedia; Credit: KENPEI






Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Betulaceae
- Genus:
- Alnus
- Species:
- Alnus japonica
- USDA Symbol:
- ALJA8
Growth Characteristics
- Height:
- 2000 cm
- Light Requirements:
- Full Sun
- Drought Tolerance:
- Low
- Bloom Months:
- mar,apr
Keystone Species Ranking
- Caterpillar Keystone:
- ★★★★★ Butterfly & moth species supported by this genus (NWF)
Garden & Ecology Notes
- Wildlife Value:
- birds, small mammals
- Fall Color:
- yellow
Soil Requirements
- Soil Type:
- rich, well-drained loamy soil
- pH:
- 5.5 - 7.5 (slightly acidic to neutral)
- Drainage:
- tolerates poor drainage
- Moisture:
- consistently moist
- Notes:
- Commonly found in riparian zones and wetlands
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–60 days
- Germination Time:
- 14–30 days
- Notes:
- Seeds require light for germination. Fresh seed germinates best; viability decreases with storage.
The above propagation data sourced from Claude AI
ORGHPS Germination Guide: Sow @ 20C. Germinates within 3 months. Requires light / surface sow (fine seed).