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Alnus (incana)

Mark E. Majerus
USDA NRCS - Bridger Plant Materials Center
99 South River Road, Rte. 2, Box 1189
Bridger, Montana 59014-9718
(406) 662-3579
(406) 662-3428 (fax)

Family Scientific Name: Betulaceae
Family Common Name: Birch Family
Scientific Name: Alnus incana (L.) Moench
Common Name: Mountain alder
Species Code: ALNINC
Ecotype: Ecotype from the Sylvan Lake area of Yellowstone National Park.
Propagation Goal: plants
Propagation Method: vegetative
ProductType: Container (plug)
Stock Type: 40 cubic inch Dee Pots
Time To Grow: 1 Years
Propagule Collection: Dormant stem cuttings (2-year-wood) were collected in late October in Yellowstone National Park. It should be noted that the wildland parent plants had evidence of repeated browsing. The cuttings were immediately placed in a cooler with the bases submerged in water. The cuttings were stored for less than 48 hours prior to placement in the greenhouse.
Propagule Processing: See below.
Pre-Planting Treatments: The cuttings were trimmed to a uniform length (6 to 10 in), bases recut at an angle, wounded, and then treated with 8,000 ppm IBA; 20,000 ppm IBA; or a combination of 1,000 ppm IBA + 2,000 ppm NAA + 40,000 ppm Thiram.
Growing Area Preparation/
Annual Practices for Perennial Crops:
Prepared cuttings were stuck individually into a 1:1 sand:perlite mix in 10-cubic-inch containers and watered in. The cuttings were then placed in a greenhouse under 16-hour photoperiods at 75 to 80øF days and 65 to 70øF nights. The cuttings were hand-watered twice per day (AM and PM) for the first 4 weeks and once per day thereafter.
Establishment Phase: After approximately 4 weeks in the greenhouse, bud break began to occur. By week 8, leaf growth advanced so a fertigation program was initiated. All cuttings were irrigated with a 350 ppm solution of 9-45-15, two to three times per week. By late January, the cuttings were rooted well enough to be transplanted into 40-cubic-inch DeepotsT in a 3:1, Fison's #3T:sand mix. The potted cuttings were returned to the greenhouse and grown on. Percent rooting ranged from 78 to 86% with a mean rooting of 82%. Based on the relatively uniform rooting, there does not appear to be any advantage to using high concentrations of IBA.
Hardening Phase: We moved all rooted stem cuttings to an outdoor hoophouse in late spring/early summer (i.e. "finished" the plants in the hoophouse). The hoophouse is ventilated but not cooled, and the containers are usually exposed to full sunlight for 2 to 4 weeks early in the season. The hoophouse was then covered with a 50% shade cloth until temperatures cooled in the fall. The shade is removed in late summer/early fall and replaced with clear plastic. The plants harden-off gradually in the hoophouse prior to winter. Bridger is characterized by a high number of solar days that keeps the environment inside the hoophouse relatively mild until winter. In the case of premature and severely cold weather, a small propane heater is used at keep temperatures above freezing.
Length of Hardening Phase: As a standard practice, we allow a minimum of 30 days of hardening off prior to killing frost, 60 days is preferred.
Harvesting, Storage and Shipping: In the case of this project, actively growing plants were delivered to Yellowstone Park. It is assumed that standard harvesting, storage, and shipping techniques for dormant deciduous plant material would apply.
Length of Storage: No experience in the storage of bareroot or container plants of this species. Rooted cuttings overwintered well in an unheated hoophouse in 40-cubic-inch conetainers.
Other Comments: Two potentially important factors in the rooting of this particular ecotype are 1) the browsing of the parent plants and 2) the submersion of the stem cuttings in water prior to sticking in the greenhouse. Heavy browsing may have the same effect as hedging, a cultural practice used on stock plants to improve rooting success. Submersion of stems in water is reported to induce adventitious root formation in this Genus in field situations and may improve the rooting of stem cuttings as well. It is not known if either of these factors contributed to the high rooting percentages observed with this collection.


Scianna, Joe. 2003. Propagation protocol for production of Container (plug) Alnus incana (L.) Moench plants 40 cubic inch Dee Pots; USDA NRCS - Bridger Plant Materials Center Bridger, Montana. 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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