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Larix (occidentalis)

Tara Luna
USDI NPS - Glacier National Park
West Glacier, Montana 59936
(406) 888-7835

Family Scientific Name: Pinaceae
Family Common Name: Pine family
Scientific Name: Larix occidentalis Nutt.
Common Name: Western Larch
Species Code: LAROCC
Ecotype: Larch/Douglas-fir forest, West Glacier, Glacier National Park, Flathead Co., MT.,1100m elevation.
General Distribution: L. occidentalis occurs from the foothills to mid- montane zones and rarely to subalpine elevations. It ranges from southern B.C. to Deschutes Co., Oregon, east of the Cascades, east to northern Idaho, northwest Montana, and northeast Oregon. It is found on moist sites in well drained soils from 650 to 2450 meters. In Glacier, there are scattered trees east of the Continental Divide in the Two Medicine area.
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Stock Type: 172 ml conetainers
Time To Grow: 7 Months
Target Specifications: Stock Type: Container seedling<br> Height: 15 cm<br> Caliper: 6 mm<br> Root System: firm plug in conetainer.
Propagule Collection: Cones are collected in September and October when cones turn purplish brown and scales begin to reflex. Mature seeds are firm and dark brown to black in color. Cones are collected by cutting branches from trees. Collections are kept in paper bags. Cones are stored in a well ventilated drying shed prior to cleaning.
Propagule Processing: Larch seeds are reported to have higher germination percentage if seed is not extracted immediately from the cones. Cones should be dried in the sun or a well ventilated shed and tumbled to extract the seeds.
Seed Storage is at least 7 years at 0C in sealed containers.
Seed dormancy is classified as physiological dormancy.
Seeds/Kg: 300,000/kg
% Purity: 100%
% Germination: 70%
Pre-Planting Treatments: Seeds are placed into a 24 hour runnng water rinse prior to cold, moist stratification for 28 to 42 days.
Non-stratified seeds of L. occidentalis germinate to higher percentages in light. Stratified seeds germinate to higher percentages in dark.
Growing Area Preparation/
Annual Practices for Perennial Crops:
Greenhouse and outdoor nursery growing facility.
Sowing Method: Direct Seeding. Seeds are covered with medium and irrigated thoroughly.
Growing mediuma used is 6:1:1 milled sphagnum peat, perlite, and vermiculite with Osmocote controlled release fertilizer (13N:13P2O5:13K2O; 8 to 9 month release rate at 21C) andMicromax fertilizer (12%S, 0.1%B, 0.5%Cu, 12%Fe, 2.5%Mn, 0.05%Mo, 1%Zn) at the rate of 1 gram of Osmocote and 0.20 gram of Micromax per 172 ml conetainer.
Greenhouse temperatures are maintained at 21 to 25C during the day and 16 to 18C at night. Seedlings are hand watered and remain in greenhouse until mid May. Seedlings are then moved to outdoor nursery for the remainder of the growing season.
Seedlings are irrigated with Rainbird automatic irrigation system in early morning until containers are thoroughly leached.
Average growing season of nursery is from late April after snowmelt until October 15th.
Establishment Phase: Medium is kept slightly moist during germination. Germinants shed the seedcoats 7 to 10 days after emergence.Seedlings are thinned at this stage.
Length of Establishment Phase: 2 weeks
Active Growth Phase: Seedlings usually reach the accelerated growth stage 6 weeks after germination.
Plants were fertilized with 25-10-10 liquid NPK fertilizer during the growing season. Seedlings can be inoculated with ecto-mycorrhizal fungi at this stage. Plants were fully root tight 23 weeks after germination and averaged 10 cm in height.
Length of Active Growth Phase: 20 weeks
Hardening Phase: Trees are fertilized with 10-20-20 liquid NPK at 200 ppm from August to September. Irrigation is gradually reduced in September and October. Plants are leached with clear water before winterization.
Length of Hardening Phase: 4 weeks
Harvesting, Storage and Shipping: Total Time To Harvest: 6.5 months

Harvest Date: September
Storage Conditions: Overwinter in outdoor nursery under insulating foam cover and snow.
Length of Storage: 5 months
Other Comments: Three L (1 gallon) containers can be produced in 2 years, with trees averaging 30 cm in height and 1.5 cm in caliper.
L. occidentalis hybridizes with L. lyallii where the elevation ranges of these species overlap.
Vegetative Propagation Method: Not tried. Softwood cuttings of juvenile stock plants of L. laricina, L. griffithii, and L. sibirica have been rooted with low percentages with 8000 ppm talc.
References: Flora of the Pacific Northwest, Hitchcock and Cronquist, 7th edition, University of Washington Press, 1973.
Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination, Baskin and Baskin, Academic Press, 1998.
The Reference Manual of Woody Plant Propagation, Dirr and Heuser, Varsity Press, 1987.
Seeds of Woody Plants in North America, Young and Young, Dioscorides Press, 1992.
Glacier National Park Native Plant Nursery Propagation Records, unpublished.


Luna, Tara; Evans, Jeff; Wick, Dale; Hosokawa, Joy. 2008. Propagation protocol for production of Container (plug) Larix occidentalis Nutt. plants 172 ml conetainers; USDI NPS - Glacier National Park West Glacier, Montana. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2021/06/17). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

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