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Fothergilla gardenii Witch Alder
Fothergilla gardenii (Witch Alder). Photo © Mary Free
You are here: Home / Plants / Tried and True Native Plant Selections for the Mid-Atlantic / Perennials / Asclepias incarnata (Swamp Milkweed)

Asclepias incarnata (Swamp Milkweed)

Asclepias incarnata (swamp milkweed) leaves
Asclepias incarnata (swamp milkweed) flower
Ascending pedicels (.4–1" long) subtended by bracts held in umbels of native Asclepias incarnata
A monarch visiting Asclepias incarnata
Asclepias incarnata (swamp milkweed) en masse at Simpson Park Demonstration Garden
Monarch caterpillar eating the leaves of host plant Asclepias incarnata
Follicles of Asclepias incarnata with oleander aphids and milkweed bugs
Dehisced follicle of Asclepias incarnata showing seeds and silky parachutes

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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. Tried and True Native Plant Selections for the Mid-Atlantic Perennial En Masse, with Pollinator,** Fruit,*** Seeds 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 Excellent Replacement for Soil Requirements: Rich, evenly moist Canna cultivars Light Requirements: Sun, Partial Shade Cleome hasslerana - Spider Flower (annual) Water Requirements: Moist, Wet Lythrum salicaria & L. virgatum - Loosestrifes To control spread: remove follicles before they split open and unwanted shoots as they appear *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. **A brown-belted bumble bee sips nectar from the flowers. ***The pictured milkweed bug nymphs pierce the follicles to feed on the seeds, helping to regulate milkweed populations. 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 developed by Master Gardeners of Northern Virginia, serving Arlington and Alexandria Images by Mary Free, Central Library Garden and private garden, Arlington

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Tried and True Native Plant Selections
 for the Mid-Atlantic

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Asclepias incarnata (Swamp Milkweed)

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.

Video © Mary Free
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 follicles (referred to as seed pods in the video) 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. Learn more about Pollinators.