Rain Garden Plants: Swamp Milkweed
Swamp milkweed is a showy perennial with large, pink to rose-purple flowers clustered at the top of tall stems. The dark-green leaves are narrow and lance-shaped, growing opposite on the branched stem. Leaves may turn purple late in the growing season. The seed pod is long and narrow, making it different than other milkweeds. After opening, small, brown seeds are dispersed via the wind. It prefers wet sites but can adapt to drier conditions and prefers soils with neutral to acidic pH. This is one perennial that can thrive in clay soils. It is a host plant for the monarch butterfly caterpillar and attracts hummingbirds, butterflies, and other pollinators. Resistant to deer browse.
- Height: 36 to 48 inches
- Bloom color: Pink; five petals
- Bloom time: June to August
- Hardiness zone: 3 to 9
- Salt tolerance: Not tolerant
- Spreading habit: Clump-forming, upright; spreads through rhizomes and wind-blown seeds
Site Conditions
- Sun: Sun/partial shade
- Soil: Moisture retentive to damp soils
- Hydrologic zone: Wet/moist; occasional flooding
Sources
- Jull, L.G. "Winter Salt Injury and Salt-Tolerant Landscape Plants. University of Wisconsin-Extension, 2012.
- Lady Bird Johnson Wildflower Center.
- PLANTS Database, US Department of Agriculture.
Prepared by Jessica Chou, Jodi Sulpizio, and Constance Schmotzer. Finalized by Jodi Sulpizio.
For a printable PDF version of this article, contact Jodi Sulpizio at jrb143@psu.edu.
