Common Milkweed (Asclepias syriaca). Monarch butterflies (Danaus plexippus) only lay eggs on plants in the milkweed family. The Milkweed host-plants are the only food Monarch caterpillars eat. Milkweed is no longer listed as an Ontario noxious weed. Sap contains cardiac glycosides that are poisonous to humans and livestock, if ingested in significant quantities. Don’t eat any part of Milkweed plants. Perennial hardy to Zone 3. Packet $1.99. 5 g $12.50.
How to Grow
140 to 180 seeds per gram. Naturally stratify seed by sowing directly outdoors in the fall in a sunny site – cover seed very lightly with soil. Indoors sow seed in a soil-less medium in early February, barely cover seed as diffuse light aids germination. Stratify seed by placing container in a refrigerator or other cold place for 3 months. Bring the container out and keep at 20 C (70 F) for the 10-18 day germination period. Grow on under lights at a slightly cooler temperature before hardening off and transplanting outside after the danger of frost has passed. Plants grow 60-120 cm (2-4′) tall. Seed from mature plants disperses easily by wind action.