Don Kinzler, Published February 14 2014
Fielding questionsQ How do you plant milkweed and when? We have tried harvesting the fluffy seeds from wild plants, but they have not grown.
– Butch Fangsrud, Moorhead
A Great question. Why would anyone want to plant weeds when most of us spend our gardening lives trying to eradicate them?
In the case of milkweed, there is a good reason to plant a few in the perennial flowerbed. Milkweed is the sole food source of monarch butterfly larvae. Without milkweeds, monarch butterflies would cease to exist.
Some varieties of milkweed make nice ornamentals. By including them in our plantings, we can help preserve monarch butterflies. Milkweeds belong to the botanic genus Asclepias, which contains 160 species. Common milkweed, Asclepias syriaca, is found throughout our region and is identified by its broad, waxy, light blue-green leaves which exude milky sap when broken off. Flowers are lavender-pink.
An ornamental milkweed found in the greenhouse trade is Asclepias tuberosa, commonly called butterfly weed or flower. It’s a perennial with pretty orange blossoms and leaves narrower than common milkweed. We used to produce this variety in the greenhouse and it performed well for our customers.
Asclepias seeds are flat, circular, brown, and found inside pods along with white, silky, fluffy strands. The fluff carries the wind-borne seed when the pods explode upon ripening.
Milkweed seed germinates better if given a cold treatment. This occurs naturally during winter if seeds are planted outdoors in the fall. For spring planting seeds can be enclosed in a plastic bag with moistened peat moss and kept in the refrigerator for at least three weeks or longer before planting. Asclepias plants can be started early indoors four to six weeks before transplanting outdoors in spring.
There is a fascinating reason why monarch larvae eat milkweeds. The sap contains a chemical that when ingested causes larvae and the resulting adult butterflies to taste bitter. Birds and predators don’t like the taste, and leave them alone.