Asclepias verticillata, Whorled Milkweed

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If you want to support Monarch Butterflies without risking the potentially large aggressive (and let’s face it, messy and brown after they die in the fall) stands of Common Milkweed, Asclepias verticillata is worth considering for your sunny garden. With an overall height never more than about 3′ and often shorter, slender upright stems and narrow leaves, it makes a dainty impression on the landscape. Furthermore, it blooms small creamy white flowers from late spring to early fall and perfumes a wide area with its fragrance.

Cultivation

Despite its high C-value (8) which indicates “a high degree of fidelity to high quality natural communities and are  typically intolerant of anthropogenic disturbance,” (Coefficients of Conservatism) many sources agree that Asclepias verticillata is easy to grow in average, dry to medium moisture, well-drained soils in full sun. As a bonus, it is very drought tolerant, and indeed, likes hot dry soils, especially sandy loam. “Plants will spread by rhizomes but are not considered invasive,” (Missouri Botanical Garden) making it a good choice for a rock garden or dry sunny bank.

Like all of the milkweeds, Asclepias verticillata does not get browsed by deer (being very poisonous to most animals) and sends down a deep taproot, making it tough to transplant. Nonetheless, it likes space around it and will not outcompete other vigorous meadow or garden plants.

Human Uses

Although quite poisonous, Whorled Milkweed was used medicinally by First Nations peoples. While something so toxic is not recommended for use, the reference cited in Wikipedia – Uses for this information are interesting. See the source material at the Native American Ethnobotany Database.

Ecology

Asclepias verticillata, like all the milkweeds, is a host plant for the Monarch Butterfly (Danaus plexippus). It is also, according to Wildflower.org, noted of Special Importance to Native Bees in general and Bumblebees in particular according to the Xerces Society. Whorled Milkweed’s primary nectar productions occurs during the early evening, attracting “wasps, honeybees, and lepidopterans such as moths and the cabbage white.” (Wikipedia, 2023)

Supports Insect Predators

Whorled Milkweed also attracts predators which help to control agricultural pest species, and so although it is treated as a noxious weed on rangeland because it is highly toxic to grazing livestock, it can support pest control on agricultural crops. This is known as “Conservation Biological Control.” Read the Xerces Society’s handbook Habitat Planning for Beneficial Insects as well as Heather Holm’s Pollinators of Native Plants: Attract, Observe and Identify Pollinators and Beneficial Insects with Native Plants.

Virginia Heritage Communities

Because it is not aggressive and likes hot dry conditions, it is only associated with Low Elevation Outcrop Barrens among Southwest Virginia’s Heritage Natural Communities.