Asclepias incarnata (Swamp Milkweed)

Tried and True Native Plant Selections for the Mid-Atlantic

This stately milkweed is at home in moist habitats across much of the United States.* It has flat terminal clusters of showy pale pink to mauve flowers in summer, succeeded by interesting fruit (follicles) that split to release seeds on silken parachutes.

*Two subspecies are recognized. Together they are widespread across the Mid-Atlantic Region: 1. A. incarnata L. ssp. incarnata is more prevalent in the northern Mid-Atlantic Region and frequent in the VA mountains. 2. A. incarnata L. ssp. pulchra is native only in the southeastern corner of PA. It is native to DC, common throughout DE and frequent in VA’s Piedmont and Coastal Plain. Both subspecies occur in NoVA, but variation incarnata is not native to Arlington and Prince William counties.

When the flowers of summer wane, pollinators move on to late bloomers, such as the mistakenly maligned native thistles. But native milkweed plants–Asclepias incarnata, A. tuberosa, and A. syriaca are still a hub of insect activity in the fall. Bright red bugs congregate on the seed pods and caterpillars hide beneath the leaves. Watch this video–listen carefully for a munching sound–and see what you are missing if you don’t grow milkweed. The monarchs are missing it too.
 – Video © 2018 Mary Free

Print Version (Legal Size): Asclepias incarnata (Swamp Milkweed)Perennial: Height: 4–6 feet; Spread: 2–3 feet; Bloom Color: Pink to mauve and whitish. Characteristics: Loose-clumping, multi-stemmed perennial; Lance-shaped, light green leaves emerge slowly in spring and in full sun may turn purplish by fall; Flat clusters of fragrant pink and whitish flowers; Green tear-shaped follicles turn to brown in fall;Spreads by seed and underground rhizomes. Attributes:Tolerates clay soil, wet soils, temporary flooding, some drought/drier soils (once set); no serious pests or diseases; deer seldom severely damage; Ethnobotanic uses; toxic when ingested without sufficient preparation or in sufficient quantity; may cause contact dermatitis; Attracts numerous beneficial insects as well as hummingbirds; good for attracting native bees; larval host for the Monarch butterfly. Growing and Maintenance Tips Soil Requirements: Rich, evenly moist Light Requirements: Sun, Partial Shade Water Requirements: Moist, Wet To control spread: remove follicles before they split open and unwanted shoots as they appear Dead foliage or flowers may harbor Monarch eggs or larvae so do not remove them until after frost Use in bogs or in butterfly or rain/water gardens Hardiness: USDA Zones 3–6 Excellent Replacement for: Canna cultivars, Cleome hasslerana - Spider Flower (annual); Lythrum salicaria & L. virgatum - Loosestrifes *Two subspecies are recognized. Together they are widespread across the Mid-Atlantic Region: 1. A. incarnata L. ssp. incarnata is more prevalent in the northern Mid-Atlantic Region and frequent in the VA mountains. 2. A. incarnata L. ssp. pulchra is native only in the southeastern corner of PA. It is native to DC, common throughout DE and frequent in VA’s Piedmont and Coastal Plain. Both subspecies occur in NoVA, but variation incarnata is not native to Arlington and Prince William counties.Learn more about other Mid-Atlantic plants: Tried and True Plant Fact Sheets