Swamp Milkweed (Asclepias incarnata)

Swamp Milkweed (Asclepias incarnata)

Swamp milkweed is a native, perennial wildflower in Wisconsin. It typically grows three to five feet tall. The flowers bloom in shades of pink, mauve, or occasionally white. Each individual flower is about 1/4 inch in diameter, but they are arranged in clusters that can be two to three inches in diameter. Lance shaped leaves grow in pairs along the stem. They are three to six inches long and one to two inches wide. This plant prefers moist to wet soils and is often found in wetlands, along streams, and in wet meadows. It thrives in full sun, but it can tolerate partial shade.

Ecologically, it plays a vital role as a host for monarch butterflies, providing both a nursery for caterpillars and a nectar source for adults, while also attracting bees, hummingbirds, and other butterflies. It adapts to garden soils with adequate watering and is hardy across much of the Midwest. In addition to its ornamental use, swamp milkweed resists deer browsing and tolerates heavy clay soil, making it suitable for rain gardens and naturalized borders. It spreads slowly via underground rhizomes and can be propagated by seed—though successful germination typically requires a chilling period to mimic winter dormancy. Historically, its fibers were used for twine and buoyant stuffing, and some Indigenous groups employed it medicinally for respiratory issues. While beautiful and ecologically beneficial, it contains cardiac glycosides that are toxic if ingested in quantity. (July)