Asclepias (cordifolia)

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

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Family Scientific Name:	Asclepiadaceae
Family Common Name:	Milkweed
Scientific Name:	Asclepias cordifolia
Common Name:	Heart-leaf milkweed
Species Code:	ASCO
Ecotype:	Rogue River-Siskiyou National Forest, Oregon
General Distribution:	Oregon, California, Nevada. Heart-leaf milkweed occurs on rocky slopes, talus, woods, chaparral, mixed evergreen forest, and lava flows, at elevations from 50 to 2000 m.
Propagation Goal:	Plants
Propagation Method:	Seed
ProductType:	Container (plug)
Stock Type:	262 ml (16 in3) container
Time To Grow:	16 weeks
Target Specifications:	Stock Type: Container seedling Root System: Firm plug in container.
Propagule Collection:	Collect seeds after pods have ripened, but before they have split open. The seeds are wind dispersed, so be careful when gathering to place in a paper or burlap bag to avoid losing them.
Pre-Planting Treatments:	Seeds are placed in fine mesh bags into a 1% hydrogen peroxide (3:1 water/3% hydrogen peroxide) soak for 24 hours, rinsed, and placed in water for an additional 24 hours. The bags are placed in sealed containers in refrigeration at 1 to 3 °C for 45 days. It is very important to check seeds 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 Nutricote controlled release fertilizer (18N:6P2O5:8K2O with minors; 180-d release rate at 21C) at the rate of 1.5 gram Nutricote per 262 ml container.
Establishment Phase:	Germination is fairly uniform and is usually complete in 10 to 14 days. Following germination, plants are fertilized with soluble 12-2-14-6Ca-3Mg at 75 ppm for 1 week.
Length of Establishment Phase:	2 to 3 weeks
Active Growth Phase:	Seedlings grow rapidly throughout the active growth phase. During the growing season, fertilization depends on weather. Soluble fertilizer (20-9-20 NPK, 20-18-18 NPK, or 17-5-24 NPK) at a rate of 100 to 150 ppm is applied weekly throughout the growing season.
Length of Active Growth Phase:	14 weeks
Hardening Phase:	No dry-down is done to induce dormancy. Seedlings are moved to an outdoor growing area in early to mid September.
Length of Hardening Phase:	2 weeks
Harvesting, Storage and Shipping:	Harvest Date: Mid 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:	Heart-leaf milkweed requires sun and porous soil, and can tolerate moderate amounts of water during its growing period. Length of storage for seed viability has not been determined.
References:	Dorena Genetic Resource Center Propagation Records, unpublished. USDA NRCS National Plant Data Center. 2006. Purple milkweed Asclepias cordifolia Benth. URL: https://plants.usda.gov/plantguide/pdf/cs_asco.pdf (accessed 9 Oct 2018).

Citation:

Riley, Lee E.; Klocke, Allison. 2018. Propagation protocol for production of Container (plug) Asclepias cordifolia Plants 262 ml (16 in3) container; USDA FS - Dorena Genetic Resource Center Cottage Grove, Oregon. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2025/04/03). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.