Joe Pye weed, related to asters, has large, hairy leaves and clusters of purple or white flowers. (The flowers resemble giant ageratum, or floss flower, heads.) Most Joe Pye weeds bloom in late summer and early autumn and attract a number of butterflies.
- Common name: Joe Pye weed, boneset, snakeroot
- Botanical name: Eupatorium spp.
- Zones: 3 to 10, depending on species
- Size: To 10 feet tall, depending on species
- From: Areas of Europe, Asia, and North and South America
- Family: Compositae (daisy family)
- Sun: Full sun or partial shade.
- Soil: Moist, but well-drained slightly acidic soil rich in organic matter. Some species, such as E. purpureum, tolerate wet soil conditions.
- Moisture: Water during times of drought.
- Mulch: Lay a 2- to 3-inch-deep layer of mulch over the soil around the plants to help conserve moisture and deter weed growth. Use winter mulch only after the soil has frozen.
- Pruning: Cut plants back in autumn after freezing temperatures completely kill the foliage or in spring before the plants begin to grow.
- Fertilizer: Fertilizer is generally not necessary in soils that are rich in organic matter. If desired, use a balanced fertilizer in spring.
- Seed: Sow seeds indoors or in the garden in spring.
- Division: Divide anytime the soil isn't frozen. Spring and autumn are best.
- Aphids: These small insects often appear in large numbers on new growth. Spray them off daily with a stream of water; they will not attack a plant after being knocked off. Use an insecticidal soap or neem-oil-based spray if infestations are severe.
- Leaf spot: In summer or autumn, the leaves develop yellow or brown spots, often with concentric rings forming something of a bull's-eye pattern. To deter leaf spot, prune plants to keep good airflow, and avoid wetting the foliage in afternoons and evenings.
- Powdery mildew: This disease tends to appear in mid- to late summer. The mildew, which looks like a gray powder, covers affected leaves and causes many to drop off. To deter the disease, prune the plant to keep good air flow and avoid wetting the foliage in afternoons and evenings.
- Rust: At first, it usually looks like leaf spotting, and it's followed by small masses of rusty-colored powder on the leaves. Infected leaves die by the end of the season. To deter it, avoid wetting the foliage; make sure there is good air circulation around plants.
- Slugs/Snails: Slugs and snails tend to eat at night, chewing up leaves. They leave slick, slimy trails behind the next morning. To deter them, try surrounding plants with a ring of horticultural grade diatomaceous earth or laying down a slug bait. Some people have found success with laying copper strips around plants, but this does not seem to work for everyone. If slugs are not particularly numerous, set out shallow containers of stale beer at ground level. Slugs, attracted to the beer, crawl into it and drown.
- The plants usually attract a large number of butterflies. Various species act as host plants for some butterflies.
- Eupatorium fistulosum: Grows to 5 feet tall and bears dark-green leaves. The plants have attractive purplish stems. The dusty-pink flowers appear in summer and autumn. Zones 3 to 8. Native to areas of North America.
- Eupatorium fistulosum ‘Gateway': Grows to about 5 feet tall and bears lavender-purple flowers appear in summer and autumn. Zones 3 to 7.
- Eupatorium maculatum: Grows to about 7 feet tall. The foliage sometimes bears purplish tones. Purple flowers appear in summer and autumn. Zones 3 to 7. Native to areas of North America.
- Eupatorium maculatum ‘Atropurpureum': This selection resembles the species, except it is a bit more compact and has darker-colored flowers. Zones 3 to 7.
- Eupatorium perfoliatum: Grows to 5 feet tall and bears white flowers in late summer. Zones 4 to 8. Native to areas of North America.
- Eupatorium purpureum: Grows to about 7 feet tall. Green leaves often carry purple tones. The pinkish-colored flowers appear in summer and autumn. Zones 3 to 7. Native to areas of North America.
- Eupatorium rugosum: Grows to 6 feet tall and bears gray-green and white flowers. Blooms in summer and autumn. Zones 4 to 9. Native to areas of North America.
- Eupatorium rugosum ‘Chocolate': Grows to about 6 feet tall. The stems are deep purple and the leaves are chocolate-brown in color. White flowers in autumn. Zones 4 to 9.