Swamp Milkweed

Swamp Milkweed (Asclepias incarnata) is a native perennial also known as Rose Milkweed. It grows across most of the central and eastern United States and into Eastern Canada, and it is hardy in USDA zones 3 to 9. In the wild it shows up along streams and ditches and in the moist parts of meadows and prairies.

Plants form upright clumps that reach about 3 to 5 feet tall, topped with clusters of pink to mauve flowers that carry a sweet vanilla scent. Bloom time runs through late summer, often July into August. Unlike Common Milkweed and Showy Milkweed, which spread widely through underground roots, Swamp Milkweed stays in place and grows in neat clumps, so it behaves well in a garden bed. It dies back in fall and returns from the roots each spring.

This is one of the better plants for Monarch butterflies. Adult females lay their eggs on it, and the leaves feed Monarch caterpillars. The flowers are also a heavy nectar source for many other butterflies, honey bees, wild bees, hummingbirds, and a long list of other insects.

Despite the name, Swamp Milkweed does not need a swamp. It does best in medium to wet soil and handles wet clay and poor drainage, which makes it a good fit for rain gardens, bioswales, and pond or stream edges. Once established it also grows fine in average garden soil. It takes full sun or part shade. For hot, dry spots, Butterfly Milkweed is a better milkweed choice.

Caution: the milky sap is poisonous if eaten in large amounts, and skin contact may cause a rash in sensitive people.