Eupatorium

( yew - pah - TOH - ree - um )

At-A-Glance Information

Known commonly as Bonesets, Thoroughwarts, or Snakeroots, these perennial flowering plants grow best in light shade in hot climates, but can take full sun elsewhere. Their water needs vary depending on the species. Clusters of colorful flowers rich in nectar and pollen will attract butterflies to the garden. Many species are considered wildflowers, and reach between 2 and 10 feet tall when in bloom. They are commonly used at the back of perennial borders, and can also do very well in meadows and other wildland plantings. These flowering beauties will create an impressive backdrop for other summer and fall-blooming perennials and ornamental grasses. Take care when planting Eupatorium in the landscape, as some species are toxic to humans and animals if plant parts are ingested.

Eupatorium Species and Varietals

The genus Eupatorium includes between 36 and 60 species and is a member of the plant family Asteraceae. The genus is named for Mithridates Eupator, King of Pontus. It gets its common name from Joe Pye, a Native American medicine man who, in the 1600's, gained notoriety for using the plant to save an entire settlement of English colonizers from Typhus fever. The best growing zones for Eupatorium vary depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Eupatorium album (Eupatorium petaloideum) (White Thoroughwort, Showy White Thoroughwort, White-Bracted Thoroughwort, Snowy White Eupatorium)
This species is native from eastern Texas through Connecticut, and its native range reaches inland as far as Indiana. Plants reach between 20 and 39 inches tall. This species grows well in USDA hardiness zones 4-9.

Eupatorium altissimum (Tall Thoroughwort, Tall Boneset)
This species is found in open woods, prairies, and fields in eastern and central United States and Canada. They can reach more than 5 feet tall when mature, and foliage is covered with whitish hairs. Flowers are dull white and bloom in springtime. Best in USDA hardiness zones 4-8.

Eupatorium cannabinum (Eupatorium nodiflorum) (Hemp-Agrimony, Holy Rope)
This species is a robust perennial native to Europe, northwestern Africa, Türkiye, Syria, Iran, Iraq, Jordan, the Caucasus, and central Asia. It is cultivated as an ornamental in many areas, and is extremely attractive to butterflies. These plants reach up to 5 feet tall and 4 feet wide, and produce dusty pink to whitish flower heads. Stems are dark red to purple. This species is considered invasive in New Zealand, the United States, and Canada.

Eupatorium capillifolium (Dog Fennel, Dogfennel, Dog Fennel, Yankeeweed, Cypressweed, Horsetail, Sneeze Weed)
These plants are native to the eastern and south-central areas of the United States, and reach up to 6 feet tall. When crushed, foliage smells similar to Dill. Flowers have a slight fragrance. This species thrives on roadsides, in tilled or burned areas, and really anywhere where soil has been disturbed. Dog Fennel is wind-pollinated, and spreads aggressively through seeds and rootstocks. Take care when planting Dogfennel in the landscape, as it can cause liver damage to humans, livestock, and pets if ingested. This species is also considered invasive in the southeastern United States.

Eupatorium dubium (Dwarf Joe Pye Weed, Coastal Plain Joe Pye Weed, Three-Nerved Joe Pye Weed, Joe Pye Thoroughwort)
This species grows best in USDA hardiness zones 3-9 or Sunset growing zones 1-9 and 14-17 and is native to the Eastern United States. It grows to 4 feet tall and just as wide and produces large domes of small lavender flowers in late summer and fall. Cultivars of the species include 'Baby Joe' (to 2.5 feet tall and wide with lavender-rose blooms) and 'Little Joe' (to 3-4 feet tall with mauve-pink flowers). This species requires moderate amounts of water to thrive.

Eupatorium japonicum (Fragrant Eupatorium, Japanese Boneset, Japanese Thoroughwort, Fujibakama, Bai Tou Po)
This native of China, Japan, and Korea forms upright purplish-red stems, and produces white, reddish-purple, or pink flowers. Bloom time is between June and November in the plant's native range. Individual plants reach up to 20-80 inches tall when mature and in bloom.

Eupatorium mohrii (Mohr's Thoroughwort, Mohr's Eupatorium)
This species is native to a range that spans from Virginia through Texas, and reaches up to 40 inches tall when mature and in bloom. Flowers are white. These plants are typically found growing in moist areas such as the edges of ponds and also appreciate more sandy substrate than other species in the genus. They are suited for USDA hardiness zones 6-9.

Eupatorium maculatum (Eupatorium purpureum maculatum) (Spotted Joe Pye Weed, Spotted Trumpetweed, Purple Boneset)
This native of the eastern United States grows to 6 feet tall and 3 feet wide. Stems are spotted purple, and plants in this species need ample amounts of water. Lime should be added at the time of planting if soil is acidic. Variety 'Gateway' is compact, bushy and grows to about 5 feet tall and has dusky-rose colored flowers. Best in USDA hardiness zones 3-9.

Eupatorium novae-angliae (New England Boneset, New England Justiceweed, New England Thoroughwort)
This rare, endangered species is found in a few counties in New England. It is a tall perennial flowering plant, reaching up to 3 feet tall at maturity. Flower heads are flat-topped, and tiny flowers are white.

Eupatorium purpureum (Joe Pye Weed)
This species grows best in USDA hardiness zones 3-9 or Sunset growing zones 1-9 and 14-17 and forms a clump of hollow stems 3-9 feet tall and 1-3 feet wide at maturity when in bloom. Leaves have a vanilla scent when bruised or crushed. Large domes of purple flowers emerge in late summer through fall. This species needs rich, alkaline soil and ample water. Variety 'Album' has creamy white blooms.

Eupatorium rugosum (Ageratina altissima) (White Snakeroot)
This species grows best in USDA hardiness zones 3-8 or Sunset growing zones 1-10 and 14-17. It is native to the eastern United States, reaching 4 feet tall and 2 feet wide, with stems and leaves heavily marked with deep brown-red. Fluffy clusters of white flowers pop in summer and early fall. It needs alkaline, rich soil and ample water. Variety 'Chocolate' has deep maroon foliage color.

Caring for Eupatorium

Take care when planting Eupatorium in the landscape, as some species are toxic to humans and animals. Eupatorium can be grown from seed or root divisions, and can also be purchased in some specialty nurseries as specimens. These flowers prefer a spot in the garden that receives full sun to partial shade. The more sun they get, the more they will flower; if they are grown in too shaded a position, they will become leggy and not produce as many blooms. Ideally, they should be receiving between 6 and 8 hours of sun each day, with some dappled shade during the late afternoon (especially in the warmer summer months or in warm growing zones). They can adapt to many different types of soil, but prefer to have their roots in moderately fertile, well-draining soil with a pH of between 5.5 and 7.0. After planting Eupatorium, mulch around the base of plants with an inch or two of organic mulching material. This will help to suppress weed growth, increase soil moisture retention, and maintain constant soil temperatures. Water new plantings regularly as they establish a strong root system. Mature plants also prefer to have moist soil around their roots; they are commonly planted around ponds and in rain gardens.

Each year in springtime, apply a feeding to the planting area using a two-inch layer of compost after pulling back mulch. Work the compost gently into the soil around plants, and replace mulch afterwards. Pinching tips in early summer will create a bushier looking plant, and deadheading plants regularly will encourage more blooms to emerge as well as discourage re-seeding. If you are looking to collect seeds for propagation, leave the seed heads on plants until they have completely dried out. Joe-Pye Weeds have a wintertime dormancy, and can be cut back to 4-8 inches from the ground in early springtime. Plants that are getting too tall or leggy can be cut back by half in summertime. Eupatorium plants are short-lived perennials, with a typical life span of between 3 and 5 years in the garden. They can naturalize in landscapes, however, providing new plants indefinitely.

Propagation

Eupatorium can be propagated either by division or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Joe-Pye Weed, follow the instructions below:

Propagating Eupatorium by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant, especially if you are propagating a hybrid or cultivar. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
These seeds will need a period of cold-stratification to germinate. To complete this process, fill a plastic bag or sealable container with moistened sand or peat moss, and place the seeds within the substrate. Put the container in the refrigerator (or similarly cool spot) for at least a months' time. After this period has passed, the seeds can be removed and sown.
In either late winter or early springtime, get your container prepared. The best time to sow Eupatorium seeds is eight weeks before the last expected frost of your area. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 1-3 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Eupatorium by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil, compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring (after the plant has entered dormancy, but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance. To propagate by division, follow these steps:

Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section attached.
Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.

Eupatorium seed heads look white and fluffy.

Eupatorium seeds are very small, and range in color from tan to brown to almost black.

Problems and Pests

Certain species are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Eupatorium has no serious insect or disease issues. For information on commonly-encountered landscape pests and diseases, including how to treat and prevent them, consult the following pages:

Pests & Pest Management

Plant issues