Eutrochium dubium aka Joe Pye Thoroughwort

Eutrochium dubium is known as coastal plain Joe Pye weed. This herbaceous perennial belongs to the daisy family. It comes from wetlands in eastern North America. Its range reaches from eastern Canada into the eastern United States. It grows in sandy swamps, along rivers, and in damp thickets. The names Eupatorium dubium and Eupatorium verticillatum are synonyms.

In gardens, plants reach 3–5 feet [0.91–1.52 metres] tall. Some reach 6 feet [1.83 metres], according to NC State. They spread 2–4 feet [0.61–1.22 metres] wide. The hollow stems have smooth surfaces marked with purple spots. Green, egg-shaped leaves grow in whorls of three or four. Each leaf has coarse teeth along its edge. Three strong veins start where the leaf meets its stalk. These veins give the leaves a wrinkled look. The leaves can feel rough or prickly.

The small flowers range from pale pink to deep purple. They form broad, domed clusters at the stem tips. Each cluster holds many tubular disk flowers, with no ray flowers. The blooms have a scent and draw bees and butterflies. Visitors include swallowtails, skippers, fritillaries, bumblebees, and carpenter bees. Flowering runs from July through September, sometimes into October. Fruit appears from August through November. Songbirds feed on the seeds.

Give this plant full sun or some shade. Dense shade does not suit it. It grows well in rich soil with plenty of humus. It also accepts damp sand, gravelly ground, and clay. NC State lists acid soil as suitable. Keep the soil moist; do not let it dry out. Dry soil can cause the leaves to scorch. The plant tolerates wet ground and suits USDA zones 3–9. Both main garden sources describe it as needing little upkeep. Cut stems to ground level in winter or late winter. New growth returns in spring.

Use it at the back of a damp border. It also fits meadows, rain gardens, and pond edges. Plant it in groups or larger masses in native gardens. Its flowers support pollinator gardens, while its seeds feed birds. It can spread through self-seeding in the landscape. Deer resistance adds to its value in open sites. Neither main garden source reports serious pest or disease problems. Both note resistance to powdery mildew.