Japanese Alder Tree Seeds

Japanese Alder Tree Seeds

(Alnus hirsuta)

Alnus hirsuta, commonly known as the Japanese alder, is a deciduous tree native to northeastern Asia, including regions of Russia, China, Korea, and Japan. It typically grows to a moderate height, reaching about 30 to 60 feet tall, with a broad, spreading crown. The tree is recognized for its rough, grayish bark and hairy young twigs, which give it its species name “hirsuta,” meaning hairy. Its leaves are simple, alternate, and ovate with serrated edges, turning yellow in autumn before they drop.

This alder species thrives in moist, well-drained soils, often found along riverbanks, wetlands, and forest edges. Japanese Alder plays an important ecological role by fixing nitrogen through a symbiotic relationship with root bacteria, improving soil fertility in its natural habitat. The tree produces small, cone-like fruiting structures called strobiles that contain numerous tiny seeds dispersed by wind. Japanese Alder is valued for its wood in local uses, including furniture and tool handles, and also serves as an attractive ornamental tree in parks and gardens due to its graceful form and seasonal color.

Zones: 6 to 8

Germination Range: 40-60%

Stratification Requirement: Seed requires 30-60 days cold moist stratification.

Planting Instructions:

stratify the seeds by placing them in a moist medium like seed-starting mix or peat moss inside a sealed plastic bag. Keep the seeds in a refrigerator at about 1 to 5 degrees Celsius (34 to 41 degrees Fahrenheit) for 30 to 60 days. This cold stratification simulates winter conditions and breaks seed dormancy.

Once stratification is complete, sow the seeds in a well-draining soil mix, preferably in seed trays or small pots. Cover the seeds lightly with soil, as they need some light to germinate but should not be buried too deeply. Maintain consistent moisture without waterlogging, and keep the temperature around 15 to 20 degrees Celsius (59 to 68 degrees Fahrenheit). Germination usually occurs within a few weeks. After the seedlings grow strong enough, they can be transplanted to larger pots or directly into the ground in a suitable outdoor location with ample sunlight and moist soil.