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Protocol Information

David J. Horvath
Nursery Manager
Illinois Department of Natural Resources - Mason State Nursery
17855 N. CR 2400E
Topeka, Illinois 61567
309-535-2185
309-535-3286
dhorvath@dnrmail.state.il.us


Family Scientific Name: Asclepiadaceae
Family Common Name: Milkweed family
Scientific Name: Asclepias sullivantii Englem. ex Gray
Common Name: Sullivant's Milkweed
Species Code: ASCSUL
Ecotype: Central Illinois, 650 feet msl elevation
General Distribution: A. sullivanti ranges from Ontario to Minnesota, south to Ohio and Kansas.
Propagation Goal: Plants
Propagation Method: Seed
Product Type: Container (plug)
Stock Type: 1+0 container plugs
Time To Grow: 7 Months
Target Specifications: Height: n/a, herbaceous perennial.
Caliper: n/a, herbaceous perennial.
Root System: firm root plug.
Propagule Collection: Source of Propagules: Seed is collected by hand from nursery stock. The plant flowers from approx. June 19 to July 15. Seed is harvested July 30th.
Propagule Processing: After drying, first clean out seed hulls and large trash by hand. Run the seed dry through the Dybvig. Next, run it through the Clipper with a top screen of 16 and a bottom screen of 7. Finally, run the good seed over the Forsberg Gravity Seed Separator.
Pre-Planting Treatments: 8 ounces of seed is saved to sow one bench in either 64 flats of the Multipot #6, or 24 flats of the Multipot #3 or #4. Seed is damp stratified by mixing it with equal amounts of vermiculite and lightly dampening in a plastic bag or container. Store this seed for 3-4 months in a cold room of 34-36 degrees F.
Growing Area Preparation/
Annual Practices for Perennial Crops:

Propagation Environment: Fully controlled greenhouse.
Container Type and Volume: Multipot #3, #4, or #6 are used. Cell volumes are 6 cubic inches, 9 cu. in. and 6 cu. in. respectively.
Growing Media: Sterile, Pro-Mix PGX. Add vermiculite and perlite at a 10:1 ratio. Mix in 5 ounces of Osmocote, slow release fertilizer, 17-6-10, per cubic foot of soil. Ensure flats are tapped down to prevent settling.
Total Time to Harvest: 7-11 months, depending on weather and plant/root development.
Sowing Date: Three crops are started in the greenhouse with the first in late December and the last no later than the end of March.
Sowing/Planting Technique: Sow the seeds by hand by broadcasting. Try to sprinkle 3-5 seeds per cell. Seed purity rates vary from year to year. Thus, it is easier to thin than to transplant. Cover the seeds to one times their depth with the same growing media. Use a dibble board or roller to gently press seed and cover soil in the cell.
Establishment Phase: Establishment Phase: Set the greenhouse temperatures to be 70-80 degrees during the day, and 65-75 degrees at night.
75% germination is reached in about two weeks.
Plants must be watered by hand during germination. Set the hose on gentle shower to prevent seeds from splashing out.
Active Growth Phase: Once germination is successful, the greenhouse temperature may be turned down gradually depending on outside temperatures. Plants are irrigated in the morning by soaking for 20 to 30 minutes. This allows the foliage to dry out during the day. Once true leaves appear, not cotyledons, the plants may be fertilized. Start with 50 ppm of Rapid Grow or Peter's Liquid Fertilizer once a week. This rate is increased to 200 ppm gradually, and, again, decreased to 50 ppm before moving the plants outside to the shadehouse. It is important to rinse fertilizer residue off the foliage by running the irrigation for 30 seconds. Plants should be thinned to 2 plants per cell. This should be accomplished before the roots are too extensive. When foliage reaches 8 to 10 inches, the plants need to be pruned back to 3 or 4 inches. This is accomplished by turning the flats on their sides and cutting with scissors or sheers. Make sure the clippings are all removed from the flats to prevent disease spread.
Hardening Phase: The first greenhouse crop will be moved to a hoop house in late January to February. To acclimate the plants, the irrigation rate is reduced to 50 ppm before moving and greenhouse temperatures are decreased to 55-60 degrees day. The second and third crops are moved directly to the shadehouse in April and May. Again, greenhouse controls and fertilization rates are adjusted in preparation for the move. Plants that reach 8-10 inches in the shadehouse will require pruning also.
Harvesting, Storage and Shipping: Harvest Date: Flats may be unplugged in October or November as long as most of the tops have died down.
Storage Conditions: Plugs that are not shipped during this fall's planting season may be stored for spring planting in cold rooms above freezing, preferably 40-50 degrees. Try to remove most of the dead foliage as you can before bagging the root plugs for storage. Store them on plastic bags to ensure the roots do not dry out.
Storage Duration: Approximately 4 to 6 months. Plugs may be shipped at any time as long as the receiver has cold storage.
Length of Storage: 4 to 6 months
Outplanting performance on typical sites: Outplanting Site: Illinois prairie sites to include State Parks, highway roadsides, and limited private lands. Prefers mesic prairies.
Outplanting Date: September to November

Citation:
Horvath, David J.; Blessman, Gary.; Flood, Roberta Mountz. 2002. Propagation protocol for production of container Asclepias sullivantii Englem. ex Gray plants (1+0 container plugs); Illinois Department of Natural Resources - Mason State Nursery, Topeka, Illinois. In: Native Plant Network. URL: http://www.nativeplantnetwork.org (accessed 1 October 2014). Moscow (ID): University of Idaho, College of Natural Resources, Forest Research Nursery.