Joe Pye Weed

Joe Pye weed (Eutrochium purpureum) is an upright, clump-forming perennial with lance-shaped leaves and large domes of tiny, vanilla-scented, pinkish-purple flowers from summer into early fall. It reaches about 5 to 7 feet (150 to 215 cm) tall and 2 to 4 feet (60 to 120 cm) wide. The flowers attract butterflies and bees, and the seed heads feed birds. It suits borders, meadows, pollinator gardens and the edges of ponds or streams.

Sowing. Sow seed outdoors in the fall, because the seed needs about 3 months of cold, moist conditions before it will sprout, and even then germination is very low. Seed can also be sown in containers in spring or autumn. Fall-sown seed produces young plants the following spring, and the seedbed should be kept moist; seedlings flower in their second season.

Other ways to start. Because seed is unreliable, you can also propagate by dividing an established clump or by stem cuttings taken in late spring. Divide in fall after the plant goes dormant; another guide suggests spring division.

Where to plant. Choose full sun to partial shade and moist, well-drained to occasionally wet soil; dry soil is not tolerated. Keep the soil consistently moist in the first year, ideally with some organic matter mixed in.

Watering. Keep the soil moist; the leaves scorch if it dries out. After the first year, plants can tolerate more drought.

Pruning. Cut the plant back at the end of the season. Cutting back before early July gives a rebloom and stockier, sturdier stems. If a Joe-Pye weed grows too tall, the stems can be cut halfway down by mid-June, and the plant will re-sprout shorter and fuller with more flower heads.

This plant is generally free of insect and disease problems, though powdery mildew and rust can occur. Powdery mildew is more of a problem on the straight species than on improved cultivars. Plants get leggy and fall over in too little light, and the leaves look scorched if the soil gets too dry.

To collect seed, cut a seed head in late September, set it upside down in a large brown paper bag, and hang the bag in a well-ventilated room so the seeds finish maturing and drop into the bag.

Collected seed can be sown outdoors in fall, or kept in a sealed bag or jar in the refrigerator until sowing.