Tom Fischer shows them being used for mid-summer, late summer, fall and winter combinations in his book Perennial Companions: 100 Dazzling Plant Combinations for Every Season.
After buying Joe Pye Weed plants for several years and seeing them fail, growing them from seed proved to be the most successful approach for my garden. I used seeds from Prairie Moon and the germination rate was terrific.
Seeds can be sown in the fall. They germinate best if they are kept warm (64 to 72 degrees) for a month, then cold (25 to 39 degrees) for at least 6 weeks. A cold frame, a cold greenhouse or winter sowing outside in containers would work. Keep them moist.
Eupatoriums bloom from July to mid-fall with a generous number of nectar flowers for butterflies followed by seeds for songbirds. Most want moist soil, afternoon shade and are easy to grow once established. They can thrive on the minerals in clay soil.
Eupatorium stems should be allowed to stand over the winter to protect the root crown from freezing. Cut them to the ground in late winter before new growth emerges.
The plant family Eupatorium was named for King Mithridates VI Eupator of Pontus (120 to 63 BC). Eupator ate a variety of poisonous leaves with the belief that it would make him immune to their effects.
Joe Pye was a New England Native American healer who used the leaves to cure typhus during the Civil War.
Joe Pye Weed, Eupatorium purpureum is a U.S. native plant that becomes a 2 to 4 feet wide clump with mauve flowers on 5 to 8 foot tall stems.
Eupatorium dubium or Little Joe is a dwarf variety that grows to 3 feet tall and 1 foot wide with reddish-lavender flowers. Baby Joe is even smaller.
E. Bartered Bride has white flowers and E. maculatum Gateway has purple stems with dark mauve flowers.Eupatorium coelestinum, Hardy Ageratum, Thoroughwort or Mist Flower, grows one or two feet tall with lots of blue flowers on red stems for 6 or 8 weeks. It will spread by rhizomes to fill in as a ground cover to accent tall grasses.
White Snakeroot (Eupatorium rugosum Chocolate) is popular with garden magazine editors. Fine Gardening calls its brown leaves and white flowers deliciously colored. White Snakeroot can be bothered by mildew, leaf spot and blight. Common names include Indian Sanicle, Squawweed and Deer-wort-boneset.
Spotted Joe Pye Weed or Smokeweed, Eupatorium maculatum, has light purple flowers.
Hollow Joe Pye Weed, Eupatorium Fistulosum, commonly called Queen of the Meadow, has white to lavender blooms atop 12-foot tall stems.
A new variety, E. fistulosum Atropurpureum, called Glow Queen of the Meadow, with rose wine flowers on red stems, received the Garden of Merit Award from The Royal Horticultural Society.
Tea made from Eupatorium cannabinum or hemp Agrimony leaves was believed to detoxify since it causes vomiting and acts as a laxative.
Boneset tea was used to ease the symptoms of dengue fever, a mosquito born disease known as breakbone fever due to the extreme joint and muscle pain.
The tea appears to have analgesic and fever reducing effects similar to aspirin.
Alternative Nature recommends burning dried leaves to repel flies. Plants for a Future Database says the leaves of Agrimony have been put on bread to prevent mold and the juice of the leaves has been used as an insect repellant for animals.
The Royal Horticultural Society Database lists these common names: Grass Root, Gravel Root, Indian Sage, Kidney Wort, Marsh Milkweed, Quill Wort, Sisters of Healing and others.