Home Native Plant Network
NPN Protocol Details Image

Juniperus (scopulorum)

Kasten Dumroese
Research Plant Physiologist
USDA Forest Service, Southern Research Station
1221 S. Main St.
Moscow, Idaho 83843
(208) 883-2324

Family Scientific Name: Cupressaceae
Family Common Name: Juniper Family
Scientific Name: Juniperus scopulorum Sarg.
Common Name: Rocky Mountain juniper
Species Code: JUNSCO
Ecotype: Northern Idaho
General Distribution: Rocky Mountain juniper occurs throughout the drier mountains and foothills of British Columbia and Alberta and south through the Great Basin and Rocky Mountains to Arizona, New Mexico, and western Texas; and north across eastern Colorado, western Nebraska, North Dakota, Montana, and into Saskatchewan. It is common in lower-elevation coniferous forests. It also occurs in montane chaparral, mountain shrub communities, and is common in the high elevation pinyon-juniper forests. In Great Plains grasslands, it mostly occurs in wooded draws, grassland-woodland interfaces, and riparian zones. It forms pure stands at middle and low elevations in the northern part of its range.
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Stock Type: 45/340 Copperblocks
Time To Grow: 2 Years
Target Specifications: 30 to 40 cm (Height) 5.7 mm (Root-collar diameter) Firm root plug
Propagule Collection: Ovulate cones, or "berries", are solitary at the tips of branches and are fleshy with a resinous pulp. Berries are globose to subglobose, 4 to 8 mm (0.16-0.31 in) in diameter. Each cone contains 1 to 3 (up to 12) round seeds that are 2 to 5 mm (0.08-0.20 in) in diameter. Rocky Mountain juniper cones remain on the tree through the winter, unless consumed by birds or other animals, then ripen and fall from the tree during winter and early spring. Cones mature by November or December of the 2nd year after pollination, and remain on the tree until March or April of the following spring. Some fleshy cones may remain on the tree for up to 3 years.
Fleshy, berry-like cones should be collected only when they are fully ripe. Cones can be collected by hand picking or hand stripping into bags or by using ground sheets spread beneath a heavy bearing shrub. Pole pruners can be used for cutting cones from taller trees (Banerjee and others 2001). Cone maturation requires two years, with both 1 and 2 year fruit found simultaneously on the same plant. Mature fruit is dark blue to nearly black in color with a white waxy coating. Avoid collecting of immature and insect damaged cones.
Propagule Processing: Following collection, minimize cone storage period prior to cleaning or store surface-dried cones under well-ventilated conditions at 1 to 3ø C and 80 to 90% humidity.
Fruit pulp is very sticky and requires presoaking in a weak lye solution or the use of citrus hand cleaner plus pumice during processing. Scianna (2001) adds citrus hand cleaner and water at intervals during processing to remove the pulp and sap from the seed, and continues adding cleaner and water until the seed appears clean and no longer feels sticky. Light seeds and debris are removed by repeatedly rinsing the seed with water. Following cleaning, sound seeds can be separated from light or unfilled seeds by flotation.There are 39,362 to 92,380 seeds/kg (17,850 to 42,100 seeds/lb).
Pre-Planting Treatments: Seeds are soaked in a running water rinse for 24 hours prior to stratification. Seeds are sown into 66 ml pine cells and placed in an unheated greenhouse for 60 days to undergo a warm, moist stratification. Next, trays are moved into the cooler (1 to 2øC)for 60 to 90 days to undergo cold, moist stratification until the end of December. Trays are then moved into the greenhouse for germination.
Growing Area Preparation/
Annual Practices for Perennial Crops:
Seedlings are grown in 2 fully-controlled greenhouses. Photoperiod is extended by incandescent lamps at an intensity of 500 lux. Irrigation is applied by overhead travelling boom system, with nozzles spaced every 40 cm (16 in). Fertilizers are applied through irrigation water by using a 1:100 injector.
Containers are filled with a 1:1 (v:v) Sphagnum peat moss and vermiculite medium having a pH of 4.2.
After sowing, seeds are covered with a shallow layer of white grit or Forestry sand (6 mm [0.25 in] deep) and immediately irrigated (acidified to a pH around 6.0) until the medium is saturated. Using a medium with low pH, irrigating with acidified water, using grit to allow air circulation around the root collar, keeping relative humidity low, and using underbench air circulation and heating prevents damping-off disease.
Day-time greenhouse temperatures are maintained at 24 to 27øC (75 to 80øF), and night-time temperatures are maintained at 15 to 21øC (60 to 70øF).
Establishment Phase: Seedlings only receive acidifed water during the first 2 weeks after germination.
Seedlings grown in greenhouses in early winter require intermittent all-night-lighting using 300 watt incandescent (15 min on/off cycles) providing about 500 lux at tree canopy height.
During weeks 3 to 9, nutrients are supplied twice per week. Seedlings are fertilized with Peters Conifer Starter (7N:40P2O5:17K2O) at the rate of 42 ppm and micronutrients.
Phosphoric acid is used to keeps pH of irrigation water around 6.0. Seedlings are irrigated when blocks weigh 80% to 85% of saturated weight. At the end of week 6, medium is leached with irrigation water to remove salt build-up.
During the second growing season,seedlings are transplanted from pine cells to 45/340 copperblocks using same medium. Without chemical root-pruning, we believe a 2 year growing regime would cause abnormal root development in a 45/340 container.
Length of Establishment Phase: 9 weeks (Year 1)
Active Growth Phase: During the active growth phase, nutrients are supplied twice a week, using Peters Conifer Grower (20N:7P2O5:19K2O) at the rate of 192 ppm N with micronutrients, alternated with calcium nitrate (15.5:0:0:10) at 51 ppm N.
Containers are irrigated when blocks weigh 80% to 85% of saturated weight, but this is slowly decreased so that by the time growers wish to initiate buds, containers are irrigated at about 70% saturated weight. Photoperiod control is continued. Medium is then allowed to dry down until it is just barely moist.
During the second growing season, seedlings receive the same fertlization regime.
Seedlings are top-pruned the second year, usually in May and again in July, each time removing about 15 cm of growth. This promotes denser shoot growth and supplies the nursery with cuttings for vegetative propagation.
Length of Active Growth Phase: 20 weeks (Year 1) 15 weeks (Year 2)
Hardening Phase: When irrigation is necessary, Peters Conifer Finisher (4N:25P2O5:35K2O) at the rate of 24 ppm N is applied every other irrigation along with micronutrients (Fe, B, MgSO4) and phosphoric acid. Calcium nitrate is applied at 51 ppm N every other irrigation. Photoperiodic lighting is discontinued. Temperatures are allowed to go to ambient, but preferably under 27øC (80øF) during the day. However, minimum greenhouse temperature allowed is -2øC (28øF). Seedlings are ready to be packed in January. From mid-September until pack-out, day temperatures are kept cool as possible and we prevent night temperatures from dropping below -2øC (28øF). Seedlings are hardened for 18 to 22 weeks.
Length of Hardening Phase: 18 weeks (Year 1) 18 weeks (Year 2)
Harvesting, Storage and Shipping: During late fall of the second year, seedlings are extracted for storage in late November through December. Seedlings are well-watered before removal but foliage should dry before packing. Seedlings are placed within plastic bags inside waxed boxes or plastic tubs and stored at 0.5øC (33 to 34øF) with relative humidity near 100%. Seedlings must be monitored for storage mold problems. Storage molds can be prevented by packing disease-free stock, storing them for the shortest possible duration, inspecting the crop for on-set of mold, shipping seedlings with minor mold occurrence first, and keeping temperatures below freezing.
Length of Storage: 4 to 5 months
Other Comments: Between crops, containers should be sterilized. We submerge containers in hot water (75 to 85øC [167 to 185øF]) for 15 to 30 seconds to remove pathogens.
Seedlings grown had similar or better morphology, higher nitrogen concentrations and contents, and higher N-use efficiency when grown with liquid fertilizer applied at an exponentially increasing rate as compared to the same amount of N applied via controlled-release fertilizers. Plants grown with a half-exponential rate were similar to those grown with controlled-release fertilizer but with a higher N-use efficiency, indicating that this type of fertilization may be a method for reducing the amounts of applied nutrients in nurseries and subsequent nutrient discharge.
References: Dumroese RK. 2003. Growth of Juniperus and Potentilla using liquid exponential and controlled-release fertilizers. HortScience 38(7):1378-1380.
Dumroese RK, James RL, Wenny DL. 2002. Hot water and copper coatings in reused containers decrease inoculum of Fusarium and Cylindrocarpon and increase Douglas-fir seedling growth. HortScience 37:943-947.
Wenny DL, Leege-Brusven A, Dumroese RK, Edson JL, Morrison S. 1996. Production of container-grown juniper for conservation plantings. In: Ehrenreich JH, Ehrenreich DL, Lee HW, editors. Growing a sustainable future; proceedings: Fourth North American Agroforestry Conference; 1995 Jul 23-26; Boise, ID. Moscow (ID): University of Idaho. p 97-99.


Dumroese, Kasten. 2008. Propagation protocol for production of Container (plug) Juniperus scopulorum Sarg. plants 45/340 Copperblocks; USDA Forest Service, Southern Research Station Moscow, Idaho. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2020/11/28). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

Personal tools