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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

Polygonum (shastense)

Lee Riley
Horticulturist
USDA FS - Dorena Genetic Resource Center
34963 Shoreview Road
Cottage Grove, Oregon 97424
541-915-7324
541-767-5709 (fax)
lee.riley@usda.gov

Family Scientific Name: Polygonaceae
Family Common Name: Buckwheat
Scientific Name: Polygonum shastense
Common Name: Shasta knotweed
Species Code: POSH
Ecotype: Crater Lake National Park
General Distribution: Lower 48 states
Propagation Goal: Plants
Propagation Method: Seed
ProductType: Container (plug)
Stock Type: 262 ml (16 in3) container
Time To Grow: 20 weeks
Target Specifications: Stock Type: Container seedling Root System: Firm plug in container.
Pre-Planting Treatments: Seeds are placed into fine mesh bags and soaked in a 1% hydrogen peroxide (3:1 water/3% hydrogen peroxide) 24 hours, rinsed, and placed in water for an additional 24 hours.
Seeds are layered in peat and placed into cold stratification (1 to 3 °C) for 60 days. It is very important to check seeds in peat weekly. If mold is evident, seeds should be treated with 1% hydrogen peroxide.
Growing Area Preparation/
Annual Practices for Perennial Crops:
Greenhouse growing facility. Seeds are directly sown into containers. Seeds are lightly covered with nursery grit. Growing medium used is 40:20:20:20 peat:composted fir bark:perlite:pumice with Apex controlled release fertilizer (16N:5P2O5:10K2O with minors; 6 to 7 month release rate at 21C) at the rate of 1.5 gram Apex per 262 ml container.
Establishment Phase: Germination is slow and uneven, and can take up to 3 weeks to be complete. During that time, plants may be lightly fertilized with soluble 12-2-14-6Ca-3Mg at 75 ppm.
Length of Establishment Phase: 4 weeks
Active Growth Phase: Plants are slow-growing, and may die back if over-irrigated. Pay careful attention to water use. Soluble fertilizer (20-9-20 NPK, 20-18-18 NPK, or 17-5-24 NPK) at 100 to 150 ppm is applied weekly throughout the growing season.
Length of Active Growth Phase: 16 weeks
Hardening Phase: No dry-down is done to induce dormancy. Seedlings are moved to an outdoor growing area in early September.
Length of Hardening Phase: 3 to 4 weeks depending on chilling hours
Harvesting, Storage and Shipping: Harvest Date: Mid to late October
Storage Conditions: Seedlings are usually outplanted in fall. No storage except in outdoor growing area. Plants are well irrigated prior to shipping and shipped in containers.

Other Comments: Found in California, Nevada, and Oregon.
Prennial shrub.
Prefers rocky or gravelly slopes.
Grows from 6900-12000 feet.
Grows in the subalpine.
References: Dorena Genetic Resource Center Propagation Records, unpublished.
The Jepson Herbarium. University of California, Berkley. Polygonum shastense. URL: https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=39288 (Accessed 5 January 2024).
Lady Bird Johnson Wildflower Center. Polygonum shastense W.H. Brewer. URL: https://www.wildflower.org/plants/result.php?id_plant=POSH (Accessed 5 January 2024).
USDA Natural Resources Conservation Service. Polygonum shastense W.H. Brewer. URL: https://plants.usda.gov/home/plantProfile?symbol=POSH (Accessed 5 January 2024).

Citation:

Riley, Lee E.; Klein, Kassandra. 2024. Propagation protocol for production of Container (plug) Polygonum shastense Plants 262 ml (16 in3) container; USDA FS - Dorena Genetic Resource Center Cottage Grove, Oregon. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2025/02/24). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.