Pinus (flexilis)

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) mmajerus@mt.nrcs.usda.gov http://plant-materials.nrcs.usda.gov/mtpmc

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Family Scientific Name:	Pinaceae
Family Common Name:	Pine Family
Scientific Name:	Pinus flexilis James
Common Name:	Limber pine
Species Code:	PINFLE
Ecotype:	Carbon County, Montana seed sources.
Propagation Goal:	plants
Propagation Method:	seed
ProductType:	Container (plug)
Stock Type:	40-cubic-inch pots
Time To Grow:	0
Propagule Collection:	Ripe cones turn a buff or light brown color in early to mid-August in south-central and southeastern Montana. Hand collect cones and place in a warm, dry environment for several days to promote opening.
Propagule Processing:	The cones are often sap covered and the seeds are frequently lodged in the cone. It may be necessary to pry out the seeds or break open the cones the extract the seeds.
Pre-Planting Treatments:	Cold moist stratify fresh seeds for 30 to 60 days at 34 to 37øF and 80+% relative humidity.
Growing Area Preparation/ Annual Practices for Perennial Crops:	We either cold moist stratify seeds in sand in a ziplock bag and then sow, or sow the seeds directly into a well-drained peat moss:sand mix (1:1 or 1:2) and then cold moist stratify. This species prefers a very well drained media.
Hardening Phase:	Move containerized material (at least 2 months old) started in the greenhouse that winter to an outdoor hoophouse in late spring/early summer (i.e. "finish" 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 is then covered with a 50% shade cloth until temperatures cool in the fall. Another option is to finish container plants in the greenhouse and then move them to the shadehouse in late summer, allowing 30 to 60 days of hardening prior to winter. The shade is usually 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:	Since nearly all containerized stock is shipped dormant from Bridger in the spring, we overwinter containers in an outdoor hoophouse. The hoophouse is ventilated when temperatures reach 35 to 40øF and heated to maintain a temperature of 5 to 10øF. The containers are placed on 2 inches of pea gravel and arranged in a side-by-side pattern. The stock is watered over the fall and winter as needed. If temperatures in the spring are too warm to assure dormancy, plant material that is designated for dormant spring planting is moved to a walk-in cooler (34 to 37øF, 80+% relative humidity) until shipping. Plants may be shipped with or without containers in heavy waxed boxes by priority ground mail (avoid weekend holdover at post offices).
Length of Storage:	Overwinters well in 1- to 2-gal containers as previously described. Should store well in a cooler for several weeks prior to shipping.
Other Comments:	Sensitive to heavy soils and overwatering. A relatively slow growing species. Propagation by seeds in containers easy based on our limited experience.

Citation:

Scianna, Joe. 2003. Propagation protocol for production of Container (plug) Pinus flexilis James plants 40-cubic-inch pots; USDA NRCS - Bridger Plant Materials Center Bridger, Montana. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/07/02). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.