Asclepias tuberosa, our native Butterfly Weed, has long been a favorite in the borders, beds and meadows here at the farm. In recent years, it’s attracted significant attention as an essential source of food for Monarch butterflies who feed on it during their larval stage. (For more information about its role in sustaining Monarchs, visit the website for the Xerces Society for Invertebrate Conservation.)
This year, it was named the 2017 Perennial of the Year by the Perennial Plant Association.
We have long encouraged plantings of Asclepias tuberosa (pronounced uh-sklee’pee-us) because, in addition to providing food for Monarchs and nectar for a wide variety of pollinators, it’s a boldly colorful bloomer that provides four seasons of interest in the garden. Hardy in zones 4 through 9S and 10W, it grows a modest 1- to 2-feet tall, making it ideal for the edge of the border. The plants produce clusters of brilliantly colored, nectar-rich orange blooms from July through September. (Asclepias tuberosa ‘Hello Yellow,’ an enhanced native variety, grows 2–to 3-feet tall and produces yellow flowers.) These plants shrug off drought, do well even in poor soil, and are deer resistant.
As autumn arrives, Asclepias tuberosa’s seedpods add interest to borders and beds. The slim, decorative pods are filled with papery seeds. As the season progresses, the pods split open, and the seeds, which are attached to silky white parachutes, scatter in the wind. The plant’s pale, empty husks remain, and as winter settles in, the pods look magnificent coated in frost and then in swirling snow. The winter beauty of this plant is not lost on Dutch designer Piet Oudolf who included Asclepias tuberosa in his design for New York City’s High Line.
A 2014 post on the Friends of the High Line blog notes: “The intricate flowers [of Asclepias tuberosa] are stars of the garden in the summer, but the empty husks of the seed pods remain an integral part of the winter garden as well. These oblong golden-gray husks are dry and slightly twisted, warped from the process of drying out. The outsides are rough and gray, with a hint of gold when the light is right. The insides are soft white, reminiscent of the silky hairs that caught the wind and carried the seeds away. These pods crown the remnant skeleton of the stem, providing a subtle, textural beauty during the deep cold of winter. These structures remind us that to High Line planting designer Piet Oudolf, ‘the skeletons of the plants . . . are just as important as the flowers.’ ”
When planting Asclepias tuberosa, be mindful of a few things. It grows best in full sun and well-drained soil (sandy soil is ideal; clay and heavily enriched soils are not). After planting, water the plant deeply then hold off until you see it begin to wilt a bit. If your Asclepias tuberosa develops yellow, chlorotic-looking leaves, it’s an indication that you’re over-watering.
Since some perennial Milkweed varieties are among the last to emerge from dormancy in spring, you might want to mark their location so you don’t plant something on top of them.
Design-wise, as with many additions to the garden, Asclepias tuberosa is most effective planted in clusters of three or more. To create an eye-popping contrast of colors and flower forms, showcase the bold bright orange blossoms alongside the deep purple flower spikes of Salvia ‘May Night’ and Liatris ‘Kobold.’ For a tone-on-tone effect, our head gardener has planted orange-flowering Asclepias tuberosa amid a sea of other orange bloomers such as Zinnia ‘Profusion Orange,’ Echinacea Butterfly™ ‘Julia,’ Butterfly™ ‘Postman,’ or Prairie Pillars™ ‘Flame Thrower,’ and Helenium ‘Short ‘n’ Sassy.’ In meadow gardens, the orange flowers pair beautifully with ornamental grasses including the 18”–30” Pennisetum ‘Hameln’ and the blue spiky foliage of Festuca glauca Beyond Blue™. They’re also a terrific companion for Amsonia hubrechtii, which has green needle-like foliage that turns into a cloud of yellow in fall.
Be aware that Asclepias tuberosa does not appreciate being moved once it’s settled in. The plants produce deep taproots that are better left alone once planted, so site it with care, let it be, and enjoy all of the benefits of this tremendously valuable plant.