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The Forest Service National Center for Reforestation, Nurseries, and Genetic Resources (RNGR) is a leading source of technical information for nurseries and land managers regarding production and planting of trees and other native plants for reforestation, restoration, and conservation.

 
NPN Protocol Details Image

Psorothamnus (spinosus)

Jean Graham
Nursery Manager
USDI NPS - Joshua Tree National Park Native Plant Nursery
74485 National Park Drive
Twentynine Palms, California 92277
760-367-5565
http://www.ggnpa.org
Family Scientific Name: Fabaceae
Family Common Name: Pea Family
Scientific Name: Psorothamnus spinosus (Gray) Barneby
Common Synonym: Dalea spinosa Gray
Common Name: Smoketree
Species Code: PSOSPI
Ecotype: Joshua Tree National Monument, California
General Distribution: Psorothamnus spinosus is found in Lower California to Sonora Mexico north to Arizona and southern California.
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Stock Type: 2 Gallon PVC Pipe containers
Time To Grow: 12 Months
Target Specifications: Height: N/A<br> Caliper: N/A<br> Root System: Firm Root Plug in container.
Propagule Collection: Seeds are hand collected in August and September when pods have matured and begin to split open. Do not collect seeds from the ground as they are often infested with insects.
Propagule Processing: Seeds are allowed to dry for 4 to 6 weeks in paper bags in a warm, dry room. After seeds have been cleaned, they are stored under refrigeration in air tight containers at 7C.
Pre-Planting Treatments: Seeds are soaked in a 1:1 (v:v) bleach:water solution for 30 to 50 mintues. seeds are leached in water for 3 to 4 hours to remove any inhibitors and to allow full imbibition of seeds prior to sowing.
Seeds are placed between sheets of blotter paper in nursery flats and wrapped in plastic bags to prevent desiccation.Seeds should not be overwatered. We transplant viable germinants into containers as soon as the radicle emerges. Flats are checked for new germinants daily.
Germination %: 40%
Growing Area Preparation/
Annual Practices for Perennial Crops:		 The Joshua Tree Native Plant Nursery is located in the Mojave Desert of southern California and has an average of 250 frost free days per year and annual rainfall of 5 to 10 cm (2 to 4 in.)
The facility is comprised of two greenhouses, shade structures, mist propagation beds and an outdoor growing compound. All propagation environments are utilized at different stages of seedling growth to provide for the variance in temperature and shading requirements during the growing season. We irrigate all containers with an automated drip irrigation system.
Establishment Phase: Seedlings are germinated during winter months in a small greenhouse were they remain for 4 weeks. Flats and containers are watered with a drip irrigation system.
After seedlings are well established and have at least 2 true leaves, they are transplanted into newspaper cylinders wrapped with polyvinyl food wrap. The newspaper container is 29 cm (11.5 in) tall and 7.5 cm (3 in) in diameter. The newspaper pots are filled with a growing medium of 2:1:1 (v:v:v) sand, mulch, and perlite.
Seedlings are susceptible to damping- off disease at 4 to 6 weeks
Length of Establishment Phase: 4 weeks
Active Growth Phase: Seedlings are ready for transplanting into larger containers at 8 to 12 weeks. The entire newspaper pot minus the plastic wrap is transplanted into the PVC tall containers using the same medium described for the newspaper containers. Osmocote time release fertilizer (9 mo release rate) (13 N:13P2O5:13K2O) is incorporated into the medium at the approximate rate of 22 g per 6l ( 2 gal) PVC containers.
PVC containers are 37.5 cm tall(15 in) and are 15 cm (6 in)in diameter.
Following transplanting, seedlings are moved to a larger greenhouse with more temperature variance where they remain for another 4 weeks.
Approximately 4 weeks old after transplanting, they are moved to the open growing compound that is covered with a 55% shadecloth during the summer months. During the months of intense summer heat, containers are irrigated by an automated drip system every other day with occasional deep irrigation to leach out accumulated salts.
Length of Active Growth Phase: 9 months
Hardening Phase: Irrigation frequency and duration is gradually reduced for 4 to 8 weeks prior to out-planting. The shadecloth is removed from the open growing compound in October when daytime temperatures begin to cool. Nursery stock is top pruned at this stage.
Length of Hardening Phase: 2 months
Harvesting, Storage and Shipping: Containerized seedlings are over wintered directly in the open growing compound.
Length of Storage: Variable; depends on out planting date.

Citation:

Graham, Jean. 2003. Propagation protocol for production of Container (plug) Psorothamnus spinosus (Gray) Barneby plants 2 Gallon PVC Pipe containers; USDI NPS - Joshua Tree National Park Native Plant Nursery Twentynine Palms, California. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/07/01). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.