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Juniperus (horizontalis)

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

Family Scientific Name: Cupressaceae
Family Common Name: Cedar family
Scientific Name: Juniperus horizontalis Moench
Common Name: Creeping juniper
Species Code: JUNHOR
Ecotype: Road cut adjacent to prairie and aspen parkland on exposed ridge, Many Glacier, Glacier National Park, MT.
General Distribution: J. horizontalis occurs in dry foothills to dry montane ridges; Alaska and central B.C. to Montana, south to Wyoming and Colorado, east to Minnesota, Iowa, and Maine.
Propagation Goal: plants
Propagation Method: vegetative
ProductType: Container (plug)
Stock Type: 800 ml containers
Time To Grow: 15 Months
Target Specifications: Stock Type: Container cutting<br> Height: 7 cm<br> Caliper: 5 mm<br> Root System: firm plug in 800 ml containers.
Propagule Collection: Cuttings are collected from healthy field plants in early to mid May. Cuttings taken in late summer, fall, and winter have also been successfully rooted to high percentages.
Propagule Processing: Cuttings are kept moist and under refrigeation prior to pretreatment. It is best to treat cuttings the same day of collection.
Pre-Planting Treatments: Vegtative Propagation Method: Pre-rooting
Type of Cutting: Semi-hardwood stem cuttings
Cuttings were recut after collection, with 1/2 of basal leaves removed. This provides a wound that promotes rooting. Terminal buds are removed and cuttings are treated with 2 minute Domain fungicide bath to remove surface pathogens. Cuttings were treated with 8000 ppm IBA and placed in mist bed with bottom heat. Cuttings were 13 cm in length, 5 mm in diameter.
Rooting %: 55%
Growing Area Preparation/
Annual Practices for Perennial Crops:
The outdoor mistbed has automatic intermittent mist that is applied at 6 second intervals every 6 minutes. Too frequent misting will result in leaf and stem rot. Bottom heat is maintained at 21C with heating cables buried 12 cm beneath rooting medium. Rooting medium is 50% perlite and 50% sand. Mistbed is covered with shadecloth during rooting. After rooting cuttings are placed in outdoor shadehouse for 4 weeks. They are later moved to full sun exposure in the outdoor nursery.
Establishment Phase: Intermittent mist is not necessary for rooting. Hand watering the rooting medium periodically is preferable to prevent fungal development on the needle-like leaves.
Time to Transplant: 12 weeks
Cuttings that were pre-rootedwere lifted out of mistbed after adequate root systems were formed. Roots generate from the nodes below the surface of the rooting medium.
Length of Establishment Phase: 12 weeks
Active Growth Phase: After cuttings were lifted from the mistbed, they were potted into 800 ml containers. Growing medium used is 50% 6:1:1 milled sphagnum peat, perlite, and vermiculite and 50% sand with Osmocote controlled release fertilizer (13N:13P2O5:13K2O; 8 to 9 month release rate at 21C) and Micromax fertilizer (12%S, 0.1%B, 0.5%Cu, 12%Fe, 2.5%Mn, 0.05%Mo, 1%Zn) at the rate of 2 grams of Osmocote and 0.5 grams of Micromax per conetainer. Cuttings were irrigated after potting and placed in the shadehouse for 4 weeks. After establishment in the shadehouse, plants were moved to full sun exposure in the outdoor nursery.
Length of Active Growth Phase: 16 weeks
Hardening Phase: Plants are fertilized with 10-20-20 liquid NPK at 200 ppm during August and September. Plants were given one final irrigation prior to winterization.
Length of Hardening Phase: 4 weeks
Harvesting, Storage and Shipping: Total Time To Harvest: 1.3 years

Harvest Date:September
Storage Conditions: Overwinter in outdoor nursery under insulating foam cover and snow.
Length of Storage: 5 months
Other Comments: Seed Propagation:
Seed Processing: Fruit is collected when berry-like cone has matured to dark blue> The cones must be two years old at this stage and distinguishable from 1 yr old cones which are covered with a powder blue bloom and are hard in consistency.
Seed Processing: The cones are macerated and seed is washed and cleaned by hand or by Dyb-vig cleaner is used. There are usually 1 to 4 seeds per cone. The seeds are brown at maturity. Seed fill rates are variable in this genus; a cutting test should be used before collection.
Seeds/Kg: 80,300/ kg
Seed longevity: up to 10 years in sealed containers.
Seed dormancy is classified as physiological dormancy.
Seed Treatments: 48 hour running water rinse followed by a 60 day warm, moist stratification and by 90 day cold, moist stratification. Juniper seeds have both physiological and seed coat dormancy which are often difficult to overcome.Scarification may also be tried prior to the pre-treatment and stratification.
The prolonged warm/cold stratification treatment is effective in producing sizable seedlings in 2 years.
Sowing/Planting Technique: Seeds are hand sown and covered with medium. treatments.
Germination temperatures should be kept at 13 to 18C until emergence. After seedlings are established,greenhouse temperatures can be raised to 16:8 hr 21/15 C day/night temperature cycle for continued growth.
References: Flora of the Pacific Northwest, Hitchcock and Cronquist, University of Washington Press, 7th printing, 1981.
Seeds of the Woody Plants in the United States, Agriculture Handbook No. 450, U.S.F.S., Washington D.C., 1974.
Glacier Park Native Plant Nursery Propagation Records, unpublished.
The Reference Manual of Woody Plant Propagation, Dirr and Heuser, Varsity Press, 1987.


Luna, Tara; Wick, Dale; Hosokawa, Joy. 2008. Propagation protocol for production of Container (plug) Juniperus horizontalis Moench plants 800 ml containers; USDI NPS - Glacier National Park West Glacier, Montana. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2020/06/05). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

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