White Swamp Milkweed 'Asclepias perennis'

White Milkweed | Asclepias perennis | Aquatic Milkweed | White Swamp Milkweed

White Swamp Milkweed, often called Aquatic Milkweed, is a stunning, native herbaceous perennial prized for its spectacular, continuous profusion of delicate, pure white or slightly pink-tinged flower clusters that bloom prolifically from early to late summer. This exceptionally tough selection is known for its remarkable ecological value—serving as an essential host plant for Monarch butterfly caterpillars and a rich nectar source for mature pollinators. Unlike many other milkweed varieties, it thrives in moist, poorly drained environments, making it a spectacular, low-maintenance thriller for damp landscape borders, rain gardens, and along the edges of ponds or water features. With its graceful, willow-like green foliage and reliable performance through challenging, wet conditions, White Milkweed offers an extraordinary display of elegant summer blooms and critical ecosystem support with exceptionally straightforward care.

Growing White Milkweed

Light: Full sun to partial shade; thrives in bright, direct sunlight (at least 4 to 6 hours per day) to produce the most abundant blooms, the strongest stems, and maintain a tight, sturdy upright form. It is highly tolerant of dappled shade, especially in hotter climates.

Soil: Rich, moisture-retentive, loamy or clay soils; highly adaptable to wet conditions and boggy areas where other plants struggle. While it prefers consistently moist environments, it will successfully adapt to average garden soils provided they do not completely dry out.

Water: Moderate to high; water regularly to keep the soil consistently moist to wet. It thrives in boggy conditions and is perfect for areas with poor drainage, but strongly dislikes prolonged drought.

Maintenance: Exceptionally low maintenance. Deadhead spent flower clusters to encourage a continuous, prolific second flush of blooms, or leave the unique, smooth seed pods for late-season interest (unlike most milkweeds, its seeds lack fluff and are designed to float and disperse by water). In the fall, cut the plant back to the base to tidy the garden and encourage healthy new spring growth. Use caution when pruning, as broken stems release a milky sap that can irritate the skin and eyes.

Wildlife: Highly attractive to butterflies, bees, and hummingbirds; serves as a vital egg-laying host and food source for Monarch butterfly caterpillars. Naturally deer- and rabbit-resistant.

Hardiness: Perennial in USDA zones 6–9; exceptionally cold-hardy and reliable across a wide range of climates provided it has adequate moisture.

Shipping Info

White Milkweed plants are shipped as healthy young starts in 4" nursery pots. Allow 1–2 weeks after arrival for plants to recover from shipping and resume active growth before repotting or planting outdoors.