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Xylorhiza (tortifolia)

Jean Graham
Nursery Manager
USDI NPS - Joshua Tree National Park Native Plant Nursery
74485 National Park Drive
Twentynine Palms, California 92277

Family Scientific Name: Asteraceae
Family Common Name: Sunflower Family
Scientific Name: Xylorhiza tortifolia (Torr. & Gray) Greene
Common Name: Mojave Aster
Species Code: XYLTOR
Ecotype: Joshua Tree National Monument, California
General Distribution: Xylorhiza tortifolia is found on dry rocky slopes and washes from 2,000 to 5,000 ft elevation; from southwestern Utah and northern and western Arizona to southern California.
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Stock Type: 2 Gallon PVC Pipe Containrs
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 when achenes have matured during May.
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: No pre treatment is used.
Seeds are directly sown in open flats using a growing medium of 2 parts sand, 1 part mulch and 2 parts perlite (v:v:v).
Germination %: 45%
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, shadestructures, 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.
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 isgradually 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.
Other Comments: This species can be directly sown to PVC pipe containers to save time.


Graham, Jean. 2003. Propagation protocol for production of Container (plug) Xylorhiza tortifolia (Torr. & Gray) Greene plants 2 Gallon PVC Pipe Containrs; USDI NPS - Joshua Tree National Park Native Plant Nursery Twentynine Palms, California. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2021/05/13). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

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