Pinaceae (Pinus)
Pinus (flexilis)
Pinaceae
Pine Family
Pinus
flexilis
(James) Rydb.
Limber pine, Rocky Mountain white pine
PIFL
Pinus flexilis grows from Alberta and British Columbia to New Mexico, Arizona, and eastern California. In New Mexico, the range of this species is limited to the northern most reaches of the Sangre de Cristo mountains in the north central portion of the state.
plants
seed
Container (plug)
164ml conetainers
Weeks
Height: 15 to 25 cm Caliper: 2 to 3 mm Root System: Firm root plug.
Entire cones are harvested by hand from trees. Cones are harvested in mid- to late September from natural stands. Because of the relatively large seed, ripe cones can also be found in squirrel caches.
Cones are placed in cone cages in a greenhouse. Greenhouse environmental controls are set to cool if temperatures exceed 27oC. Once opened, cones are removed and tumbled in a cone tumbler and the seed is collected. This process yields both seed and some cone detris. The seed left over in the cone cage during the cone opening process is collected and added to the seed and detris collected during cone tumbling. The seed/detris mix is rubbed gently in a rubbing box to separate wings from the seed. The seed is then cleaned by separation in an air column. This process has shown to be effective in separating nearly all of the detris from the seed. Cleaned seeds are refrigerated (2 - 4oC) until use if use is expected within 12 months. If the seed is not intended to be used within 12 months, the seed is stored at -9 to - 12oC.
Seeds are removed from storage and placed in water at room temperature for 12 - 18 hours. The moistened seed is then placed into self-sealing, polyethylene baggies and stratified for 90 days. Stratification temperatures range from 2 to 4oC
Propagation occurs in a greenhouse and outdoor nursery (shade house) facility. During establishment and the initial portion of the active growth period seedlings are kept in the greenhouse. During the later portion of the active growth period through the storage period seedlings are kept in the shade house. Seed is sown in early April and seedlings are moved into the shade house throughout August when seedlings are between15 and 25 cm tall. Growing media is a 2:1:1 (v:v:v) peat:perlite:vermiculite mixture. Controlled release fertilizer 14-14-14 (N-P-K) 3 -4 month is incorporated into the media at the rate of 4 kg/m3. Greenhouse irrigation is provided via mini-sprinklers. Irrigation heads are spaced to provide head to head coverage. Shade house irrigation is provided via sub-irrigation beds. Seedlings are fertilized using a fertigation system, which utilizes the irrigation an overhead sprinkler system using standard fixed area turf sprinklers. Irrigation in the cold frame is done using sub-irrigation beds. Irrigation intervals are typically every 4 to 5 days while in the cold frame.
(Greenhouse) Seed is placed on top of the media. A 2 to 5 mm layer of perlite is placed on top of the media/seed to serve as a mulch. The containers are irrigated (misted) 4 to 8 times daily to keep the surface of the media moist. Greenhouse night and day temperatures range from 18 to 26øC and no supplemental light is provided. Thinning of germinants to one seedling per cell begins after 14 days. The container system used allows for the consolidation of germinants to separate containers, which are removed from daily misting. Consolidation begins after 14 days.
28 days
Containers are irrigated as needed, which usually involves irrigation once every 4 to 5 days for the first several weeks then one every 2 to 3 days through the remainder of the active growth period, typically by week 18. Containers are allowed to dry down to a moderate state between irrigations. This irrigation regime is used to help minimize root disease problems. All irrigations are done early in the morning, which allows foliage to sufficiently dry before nightfall, minimizing foliar disease problems. During the active growth phase, seedlings are fertigated every irrigation with a liquid based fertilizer (20-10-10; N-P-K). Fertilization rates applied progressively increase throughoutthe active growth phase. Applications rate begins at 25 ppm N for the first 2 weeks and progressively increases by 25 ppm every two weeks. By week thirteen seedlings begin receiving 175 ppm N and this rate is held until the seedlings are moved to the shade house. Once in the shade house, seedlings are fertilized with 150 ppm N every third irrigation until the end of August. During the greenhouse portion of the active growth period greenhouse temperatures during the day are 21 to 26øC and during the night 18 to 22øC. Ambient photoperiod is supplemented with 60 min light interruptions at the mid point of the dark cycle (10 - 14 hrs) from 75 watt incandescent lights suspended 2 meters above greenhouse benches and from 1,000 watt high pressure sodium vapor lights suspended 3.5 meters above the crop. Once transferred outside, ambient temperature and light regimes are utilized.
16 to 20 weeks
(Shade house) This phase begins in late summer (end of August typically) to early fall as soon as seedlings attain their target shoot height. Containers are leached with a heavy irrigation and a series of incrementally increasing water stresses is applied to restrict any further height growth. In Mora, NM, ambient day temperatures are still quite warm but nights begin cooling markedly. The interval between irrigations becomes progressively longer due to seedlings becoming acclimated to water deficits and the gradual cooling associated with the onset of Fall. Seedlings are fertilized every third irrigation (fertigated) with a liquid based fertilizer (10-30-20; N-P-K) at a rate of 25 ppm N.
9 to 12 weeks
(Cold Frame) Seedlings are moved from the shade house into a cold frame (low-tech, twin-walled poly-topped greenhouse) in late October to early November. This step is necessary as the diurnal fluctuations in temperatures throughout the winter can result in daily freeze/thaw episodes which can damage the seedlings. The temperature in the cold frame ranges from 2 to 4oC day and night. Irrigation in the cold frame is done using sub-irrigation beds. Irrigation intervals are typically every 4 to 5 days while in the cold frame. No supplemental light is provided. Seedlings are kept in the cold frame until shipped which is typically in late February or early March.
3 - 4 months
[ITIS] Integrated Taxonomic Information System. 2008. (On-line database). http://www.itis.gov Steele, R. 2004. Limber Pine. In (R.M. Burns & B.H. Honkala Tech. Coords.) Silvics of North America. Volume 1. Conifers. http://www.na.fs.fed.us/Spfo/pubs/silvics_manual/volume_1/silvics_vol1.pdf
Harrington, John T. 2010. Propagation protocol for production of Container (plug) Pinus flexilis (James) Rydb. plants 164ml conetainers; New Mexico State University-Mora Research Center Mora, New Mexico. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/12/22). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.
