Swamp Milkweed

Swamp milkweed

The vibrant pink blooms of swamp milkweed (Asclepias incarnata) will stand out in any rain garden. This great pollinator plant naturally grows in wet meadows and is suited for the low zone of your rain garden.

Swamp milkweed will grow in sand, loam and clay soils and thrives in full sun but can tolerate some shade. Not salt tolerant, swamp milkweed should be planted away from any hard surfaces that are salted in the winter. Its long taproot is delicate, so take care when transplanting.

The height of swamp milkweed is quite variable, growing between 30 and 120 centimetres tall. The central stem has pairs of long, narrow leaves that often turn from a green-burgundy to yellow in fall.

Most plants have some branching, each one showcasing a large cluster of delicate, bright pink, fragrant flowers. In late summer, the flowers form long, narrow seed pods that will dry and split as winter approaches. The seeds spread, carried along on what look like small, white, fluffy umbrellas.

The flowers attract a variety of pollinators including bees, butterflies and hummingbirds. Like other milkweeds, swamp milkweed is a host plant for the monarch butterfly. Watch for adult monarchs who may visit to lay their eggs on the leaves. Once the eggs hatch, the emerging caterpillars will feed on the leaves.

Non-native aphids also enjoy feasting on swamp milkweed. Lady beetles may help control the aphid population, but you can also squish the aphids when you see them or remove them with a strong spray of water.

Swamp milkweed pairs well with other low zone rain garden plants like harlequin blue flag, white meadowsweet and common boneset. Together, they can create a colourful, pollinator-friendly rain garden that improves water quality and brightens our communities.

Photo credit: Jon Clayton

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