Common milkweed blooms in early summer, the flowers arranged in a spherical cluster.
By late summer the seed pods appear, these will ripen, split and release their fluffy seeds in late fall and winter.
The milkweeds are familiar wildflowers throughout North America, and the aptly named common milkweed (Asclepias syriaca) is the most common species in the East. One of the largest members of the genus, common milkweed can reach 6 ft (2 m) in height, although 3-4 ft (90-120 cm) is more typical. The stems are usually unbranched. As do all but two of the more than one hundred milkweed species, this one has opposite leaves and milky sap. The leaves of common milkweed are oval-elliptic, softly hairy, bluish green below, and 4-10 in (10-25 cm) long. As do all the milkweeds, common milkweed has flowers with a lower ring of five sepal-like lobes (the calyx); an outer ring of five reflexed petal-like lobes (the corolla); and held above that, a crown consisting also of five lobes (the corona).
The flowers of common milkweed have purplish green corollas and pinkish coronas borne in nodding umbels around 2 in (5 cm) across. Flowers sometimes can be white, but are always fragrant. The spindle shaped follicles (seed pods) of common milkweed are up to 5 in (12 cm) long, usually in pairs, and point upward on drooping peduncles. Most milkweed pods are smooth, but those of common milkweed are covered with soft, flexible spine-like protuberances. The pods turn brown and split open when ripe to release seeds which are carried on the wind by tufts of long silky floss-like hairs.
Common milkweed (Asclepias syriaca) is a very wide ranging wildflower that grows naturally throughout most all of North America east of the Rockies from Saskatchewan east to Quebec and Newfoundland, and southward to Texas and Georgia, not quite as far south as Florida. In western North America and the Great Plains, the very similar showy milkweed (A. speciosa) is the most frequently encountered species. Common milkweed grows (often abundantly) in meadows, old fields, road shoulders, and waste places – anywhere with sandy soils and abundant sunshine. It can become weedy. Often cultivated in butterfly gardens, common milkweed has expanded its range and become established in parts of Europe and western North America.
Culture Light: Grow common milkweed in full sun. Moisture: Common milkweed likes a light, well drained soil and can tolerate brief dry spells. It does not do well in moist or compact soils. Hardiness: USDA Zones 3 -9. Propagation: Cuttings from the outward spreading fleshy rhizomes can be used to propagate common milkweed. Seeds can be started in containers in early spring.
Here milkweed grows at the margin of a woodlot but is happy to grow almost anywhere there is enough sunlight.
Common milkweed is usually considered a tenacious weed and something to be removed from farms and gardens. However, just because it is vigorous and abundant doesn’t mean it isn’t a desirable native wildflower. Common milkweed should be grown in butterfly gardens because the nectar-rich flowers attract all manner of insects (including bees and butterflies), and milkweed foliage is the sole food source for monarch and queen butterflies. This is a vigorous wildflower and one that is easy to maintain in cultivation. Sometimes caterpillars may completely defoliate a milkweed plant, but this rarely kills it and the plant will almost always recover. Common milkweed, with its large leaves, is rather coarse and, aside from the butterfly garden, best suited to herbaceous borders and naturalizing in the wild garden. The flowers and dried pods are attractive in arrangements.
Native Americans used various parts of common milkweed as medicines both internally and externally, and the young shoots, leaves and immature pods were cooked as greens. They wove sewing thread, rope and fabric from the tough fibers of the outer stem. The silky floss was used to stuff mattresses and pillows and to start fires.
The floss of common milkweed has outstanding insulation and buoyancy properties. During World War II, Americans (especially children) gathered tons of the stuff for use by the military as flotation in life jackets. Research continues on other potential uses for milkweed including for medicines, pesticides, insulation, oils and biofuels.
The caterpillars of the monarch and queen butterflies eat milkweed leaves and stems, and in so doing they accumulate glycosides (like digitalis used to treat heart disease) from the plant. These toxins render the caterpillars and eventually the adult butterflies distasteful and toxic to birds, lizards and anyone else who might bite into one.
The milkweeds were formerly classified in their own family, the Asclepiadaceae, but recent authorities have concluded that they actually belong in the dogbane family.
Milkweed can be toxic to herbivores, like cows and sheep, that ingest large amounts of the latex along with the stems, leaves and mature follicles. Although the milky white latex sap is toxic (and so bitter to the taste that one wouldn’t consume it anyway), the young leaves, shoots, flower buds and immature follicles are edible, even without cooking according to some authorities.