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Alnus (incana)

Randall Lester
Assistant Manager
USDA NRCS - Appalachian Plant Materials Center
P.O. Box 390
Alderson, West Virginia 24910
304-445-7049 (fax)

Family Scientific Name: Betulaceae
Family Common Name: Alder
Scientific Name: Alnus incana (L.) Moench
Common Name: Speckled alder
Species Code: ALINR
Ecotype: Monongahela National Forest
General Distribution: Widely distributed in the northeastern United States. Also widely distributed in the eastern 2/3 of Canada.
Known Invasiveness: Not known to be invasive.
Propagation Goal: Plants
Propagation Method: Seed
ProductType: Container (plug)
Time To Grow: 7 Months
Target Specifications: A well developed plant suitable for transplanting with at least 12" of top growth and a healthy root system.
Propagule Collection: Mature cones were collected in late fall of 2017. Most of the cones were still green though some had started turning brown as they matured.
Propagule Processing: The cones were spread out on a table covered with paper to allow for air drying. A fan was used for circulation to aid in the drying process. Once dried, the cones were processed through a brush machine which tumbles the cones and allows the seed to separate. We used an aspirator to separate the good seed from the unfilled seed and other debris. Care should be taken to make sure the seeds are not dried too much which could damage the embryos.
Pre-Planting Treatments: Seeds were direct sown as soon as they were ready. No pretreatment was used.
Growing Area Preparation/
Annual Practices for Perennial Crops:
A table was prepared in the greenhouse with 2" X 4" lumber sides and clear plastic placed underneath. Two layers of growing media were used. The bottom layer was composed of 2" of Black Kow brand cow manure. On top of this, we placed 1 1/2" layer of Sun Gro Metro Mix 510. The layers were compacted slightly to make a firm seedbed for sewing the seed.
Establishment Phase: Because speckled alder seed historically does not store well, the seeds were sown as soon as they were cleaned. The seeds were spread evenly by hand over the soil surface. A thin layer of sand was spread on top of the seed to help dissipate the impact of the irrigation water and to help ensure good seed to soil contact. The table was watered daily to ensure adequate moisture for germination.
Length of Establishment Phase: 3 Months
Active Growth Phase: Seeds started to germinate in 7 days. The plants grew fairly slowly at first but were large enough to transplant with sufficient root systems in about 3 months. Larger seedlings were removed by gently pulling them up. Care was taken when removing the seedlings to disturb the soil surface as little as possible so other seeds could germinate. Seedlings were transplanted into SureRoots 50 cell deep plug trays and placed back in the greenhouse.
Length of Active Growth Phase: 3 Months
Hardening Phase: The plug trays containing the speckled alder were moved outside for 1 month to allow for hardening off before being shipped.
Length of Hardening Phase: 1 Month
Harvesting, Storage and Shipping: The speckled alder plants were shipped back to the Monongahela National Forest in the plug trays to prevent them from drying out too much before being planted. The trailers used for shipping were covered with tarps to protect the plants and prevent wind burn.
Length of Storage: 1 Day
Outplanting performance on typical sites: Speckled alder occurs primarily at higher elevations in areas that are cool and wet. They are often found along stream edges and wet meadows where they can form vast thickets. Speckled alder is adapted to a wide variety of soils and is valuable for erosion control along waterways and in disturbed areas.
Other Comments: We are finding that the seeds germinate at different times so this is an ongoing process. The table that we used for germinating the seeds is still producing numerous seedlings even after 10 months in the greenhouse. Some seeds germinate and grow into small seedlings, the larger ones are transplanted and other seeds germinate to take their place.


Lester, Randall; Vandevender, John. 2018. Propagation protocol for production of Container (plug) Alnus incana (L.) Moench Plants USDA NRCS - Appalachian Plant Materials Center Alderson, West Virginia. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2020/09/18). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

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