Swamp Milkweed (Asclepias incarnata)

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Botanical name: Asclepias incarnata • Bloom season: Summer‍ ‍• Bloom color: Mauve-pink‍ ‍• Host plant (Great Basin): monarch, queen

Upright stems topped with domed clusters of mauve-pink, and a light vanilla scent on a warm evening. It is the milkweed for the wet spot: the one place in a Northern Nevada garden where the soil stays damp and most of this catalog would rot. Monarch and queen caterpillars both feed on it, and the flowers pull in swallowtails and bumblebees at the height of summer.

Botanical name: Asclepias incarnata • Bloom season: Summer‍ ‍• Bloom color: Mauve-pink‍ ‍• Host plant (Great Basin): monarch, queen

Upright stems topped with domed clusters of mauve-pink, and a light vanilla scent on a warm evening. It is the milkweed for the wet spot: the one place in a Northern Nevada garden where the soil stays damp and most of this catalog would rot. Monarch and queen caterpillars both feed on it, and the flowers pull in swallowtails and bumblebees at the height of summer.

Size:

Plant Characteristics

Botanical Name: Asclepias incarnata

Common Name: Swamp Milkweed

Native: Native

Sun: Full Sun

Water: Moderate

Bloom Time: Summer

Bloom Color: Mauve-pink

Pollinators: Bees; Butterflies; Moths

Deer Resistant: Yes

Mature Size: W 2'-3' x H 3'-4'

Soil: Moist to average

Plant Type: Herbaceous perennial

USDA Zones: 3 to 9

Spread Habit: Clumping

Available As: Live plant

Native Region: Eastern & Central N.A. (outside western regions)

Host Plant (Great Basin): monarch, queen

Host Plant (Elsewhere in North America): delicate cycnia

Growing Notes

Full sun and consistent moisture. This is the exception to the low-water rule that governs most of the shop, so put it where a downspout drains, at a pond edge, or in an irrigated bed. Space about 2 feet apart. Unlike showy milkweed it clumps rather than runs, so it behaves in a border.

  • Water: Moderate

  • Sun: Full Sun

  • Soil: Moist to average; the one milkweed here that wants regular water

  • Mature size: W 2'-3' x H 3'-4'

Maintenance

Leave stems standing through winter and cut back in late spring, keeping about a third for overwintering insects. Do not spray aphids; systemic insecticides move through the plant and kill monarch larvae. It emerges slowly in spring, often not showing until well into May, so mark its position to avoid digging into the crown. Divide only if you must, since the roots resent disturbance.