Late Boneset – A Complete Guide To Eupatorium serotinum


Late Boneset is a herbaceous perennial wildflower native to Eastern North America. Scientifically known as Eupatorium serotinum, it grows 3-6′ tall in full sun and well-draining soil. Blooming white flowers for one month in late Summer, it attracts a staggering amount of pollinators with over 100 species documented.

In this article:

What is Late Boneset

An often overlooked flower, Late Boneset blooms white flowers in late summer, usually the same time as many of the Goldenrod species, but never receiving the same level of attention. The flowers are attractive when examined, but since they are numerous and small it makes for more of a background flower rather than a focal point. [1][2]

Typically found along roadsides, abandoned fields, powerline cuts and similar areas, Late Boneset can be a weedy aggressive plant that will outcompete many other species in disturbed areas. One of the more common places I see big colonies is along roads that were recently built. As once this plant finds it’s way there it can send rhizomes out, further occupying any bare spot in the soil.[3]

Late Boneset is one of those flowers that may find you, rather than you seeking it out! The seeds travel really well on the wind. Similar to Fleabane Daisies or Frost Aster, this plant has a habit of just ‘showing up’ in your garden.

That is what happened to me. I never planted it, but had some volunteers show up in my backyard micro-prairie. This was back in 2019 and had never seen it before. But I was quite impressed with how busy this plant was with pollinators. It is quite and amazing species in it’s ability to attract a huge variety of insects.

Native Range of Late Boneset

The native range of Late Boneset is the Eastern United States, from Texas to Florida and North to parts of Nebraska to Delaware. It has already increased it’s range substantially, as it is very well established throughout Southern Pennsylvania in just a few years. This is most likely facilized by seeds following roadways when being dispersed from wind.

Click for full size. Source [1]

It has expanded beyond it’s native range though, colonizing areas of Minnesota, Ontario, Pennsylvania, and areas of New England. This probably isn’t due to being cultivated by gardeners though, more likely a consequence of the Interstate Highway System making it easier for seeds to ‘hitch a ride’ on vehicles.

Although it is quite aggressive in North America, it has not been noted as being invasive in other parts of the world outside of Australia.[2]

Late Boneset Reference Table

Scientific NameEupatorium serotinum
Common Name(s)Late Boneset, Late-Flowering Thoroughwort, Late Thoroughwort
Native Range, USDA ZoneSoutheastern United States, USDA zones 4-8
Bloom TimeLate Summer
Bloom Duration, ColorFour weeks, White
Height3-6′
Spacing / Spread3-4′
Light RequirementsFull sun to partial shade
Soil TypesSandy loam to clay loam
MoistureMoist to medium-moist
Fauna Associations / Larval HostsNumerous pollinators visit / Hosts several moth species
Sources [1][2][3][4][5]

What are the Pros and Cons of Late Boneset

Pros

Pollinators

A true pollinator powerhouse! Late Boneset attracts well over one hundred species of pollinator late in Summer when it begins blooming. If you see a patch blooming, go examine it. You are sure to find species you didn’t even know existed!

Skipper and wasp on Late Boneset in my backyard.

Adaptable

Late Boneset can tolerate a wide variety of growing conditions. Although it prefers full sun beyond all else, it can often thrive in tough areas such as roadsides or dividers on interstates.

Beauty

When planted en masse, Late Boneset adds a nice shade of white coloring that looks nice compared to most of the other plants that have gone dormant. It also contrasts nicely with Goldenrod, which generally dominates roadsides/powerline cuts/pastures.

Cons

Aggressive

Although Late Boneset has some outstanding benefits, unfortunately it can be a very aggressive spreader, similar to Canadian Goldenrod or White Snakeroot. And this aggressiveness makes it difficult to grow in smaller suburban gardens.

Identification and Characteristics of Late Boneset

Stalk

Stalks are round, green to reddish brown and covered with short white hairs.

Leaf

The leaves of Late Boneset are typically 2-7″ tall, lanceolate in shape, and smooth with serrated margins. They are generally opposite in arrangement in the lower portion, but can be alternate in the upper half of the plant. And this can make identification a bit difficult.

Leaves and stalk of Late Boneset in late Spring
Leaves in late Summer / early Fall

Flower

The inforescense of Late Boneset is of numerous compound corymbs of white disc florets. Each flowerhead has around 12 florets that are roughly 1/4″ tall by 1/8″ diameter. Each floret is tubular with 5 lobes and a long style that protrudes out giving a somewhat hairy/fuzzy appearance. Flowers do give off a nice scent. Blooming begins in late Summer and lasts for approximately four weeks.

Close up of flowers

How to save seed from Late Boneset

About 6 weeks after blooming, seed heads will have formed where the flowers once were. Small achenes (seeds) will be attached with a small tuft of hair and are carried by the wind.

Seed heads of Late Boneset

To save seed of Late Boneset, clip off the seed heads once they appear dry but before they blow away. Place the flowerhead (and seed) in a paper bag and allow it to dry for a week in a cool dry place such as a garage.

Individual seeds of late Boneset

Shake the bag to release the seed. Remove the flower stalks, and dump the seed/chaff onto a plate. Put the dry seed into a ziplock bag or envelope and label/date it. Fully dried Late Boneset seed can be stored in a dark, dry place for a couple years without losing much viability.

Root system

The root system of Late Boneset is that of a fibrous crown and rhizomes.[3] Rhizomes are underground spreading roots that sprout new plants. This characteristic obviously makes Late Boneset aggressive.

Is Late Boneset aggressive?

Late Boneset spreads aggressively in disturbed areas from self-seeding and rhizomes, similar to other ‘weedy’ late bloomers such as Canadian Goldenrod or White Snakeroot.

Controlling Late Boneset

Mechanical control

Late Boneset is an aggressive spreading wildflower that can easily get out of hand in formal flower beds or manicured gardens. Control can be achieved by several mowings throughout the year, one in mid-Spring, and then a second when blooming but before seed heads form.

Chemical control

One can control Late Boneset via application of chemical herbicides such as 2-4-D and other broad-leaf herbicides. This has been done to eradicate Late Boneset outside of it’s native range in various locations such as Australia. [2]

Grow and Care for Late Boneset

Sunlight Requirements

Late Boneset prefers and grows best in full sun, which is at least six hours of direct sunlight. It can grow in partial shade, but will not be as large, vigorous, or showy.[2][3]

Soil Requirements

For soil texture, Late Boneset officially prefers loamy soil with lots of organic matter (like almost any plant). But I have seen this plant takeover and dominate new construction areas with poor compacted soil. It had no problem colonizing my wildflower area (I didn’t plant it, it just showed up) that has over-compacted sandy-loam.

Moisture Requirements

For moisture, Late Boneset will grow best in moist to medium-moist soil that drains well. If you are unsure of your how your soil drains, see our guide how to test it.

Maintenance

If planted in a wild area or border garden, Late Boneset will not need any special care. But unwanted seedlings can be mowed or manually removed.

If grown in the open, Late Boneset may lean or flop over, and require staking to keep it upright.

Fertilizer

Late Boneset will not require any supplemental or special fertilizer.

How to Grow Late Boneset from Seed

Late Boneset is fairly easy to grow from seed. The seed has a dormancy of 60 days cold moist stratification (minimum 21 days [6]), which can be achieved from using the refrigerator (in a process described here), or by Winter Sowing the seed by late January. My personal preference is to Winter Sow, as it is easy with no risk of mold. Also, the seed should not be buried, but surface sown as exposure to sunlight will aid in germination.

Process to germinate Late Boneset seeds in containers

The following steps assume you have either cold-stratified your seed in the fridge for sixty days, or are Winter Sowing the seed.[6]

  • Fill a suitable container with moist potting soil
  • Sprinkle Late Boneset seed on top of the soil
  • Press the seed in with your thumb
  • Place the container in a location that receives morning sun and afternoon shade
  • Germination will occur once temperatures warm up in Spring.

Seed sown on or near the surface has a tendency to dry out, which can prevent germination. To overcome this, I strongly recommend that you keep containers with sown seed in locations that receive morning sun and afternoon shade.

Late Boneset seedlings that I Wintersowed.

Also, only water in the morning by misting so not to wash away or bury seed. Watering in the morning also prevents damp off disease, as sunlight will remove excess water at the soil/stem interface via evaporation.

Direct sowing Late Boneset seed

Seed of Late Boneset can be directly sown in disturbed areas in Fall or Winter. Simply scatter the seed on a calm day, then walk or drive over it to ensure good contact with the soil. Germination should occur once temperatures warm up in Spring.

Wildlife, Pests, and Diseases associated with Late Boneset

Pollinators

Late Boneset is incredibly popular with a wide variety pollinators late in the season. Charles Robertson in his extensive survey counted no less than 132 different species of pollinator visiting Late Boneset.[4] These included long-tongued bees, short-tongued bees, wasps, flies, beetles, butterflies, moths, and skippers.

In addition to pollen and nectar, several species of moth are hosted by Late Boneset including the Clymene Moth, Ruby Tiger Moth, Eupatorium Borer, and several other beetles. [5]

Pests

Deer and Rabbits

In general mammals (including deer and rabbits) avoid eating Late Boneset as the foliage is bitter. It is known as an ‘increaser’ in pastures, as livestock avoid grazing on it, but eat everything else, which reduces competition.

Disease

Once blooming starts you will notice various foliar diseases effecting Late Boneset. These are cosmetic and not fatal to the plant. Also, Late Boneset is noted for being very resistant to powdery mildew. [3]

Where you can buy Late Boneset

Late Boneset is not typically sold in nurseries, as it isn’t a typical ‘garden friendly’ plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map.

Where to buy seeds

There are various specialty seed companies that sell Late Boneset seed. However, if you live within it’s native range it isn’t to hard to locate and forage some seed….or just wait for Late Boneset to find you! (as it did to me)

Uses of Late Boneset

Garden Uses

In the garden Late Boneset is best used as a border flower or a component of a micro-prairie or wildflower meadow. It is not suitable for smaller mulched flowerbeds, as the thousands of seeds it will produce will make it a nuisance, as well as it spreading vegetatively via rhizomes. Also, it has a tendency to flop or lean when not surrounded by competition, which is another factor that must be considered when planting.

Late Boneset, leaning over next to Aromatic Aster.

This can be overcome though, as planting it inside a large pot with the bottom cut out, or a large pot lined with landscape fabric can help limit the rhizomes ability to spread. (See examples of this method here) But it won’t stop it completely (based on my experience with other species).

Erosion control and mine reclamation

The high germination rates of Late Boneset seed combined with it’s adaptability for various growing conditions make it an excellent choice for a pollinator friendly form of erosion control. In addition to quickly colonizing disturbed areas, it also has successfully been used for mine reclamation. [7]

Companion Plants

Other species that grow well with Late Boneset include anything that likes full sun, and moist to medium moist soil. Some great companion plants include the following:

Medicinal Uses

Flowers of Late Boneset were used by the Houma Tribe to treat typhoid fever. The flowers were boiled to extract medicine, and this was then (presumably) the liquid would be drunk. [8]

Final Thoughts

Late Boneset is an incredibly important flower for pollinators and wildlife. It can add some beauty to the landscape, but more as a ‘background’ plant rather than a focal point. These benefits need to be balanced against it’s aggressive nature though, as it probably shouldn’t be planted in a formal flower bed unless you take steps to limit it’s spread by deadheading or containing the rhizomes.

Find more native plants here

References:

[1] – Eupatorium serotinum, USDA NRCS. Accessed 07AUG2023.

[2] – Tomley, A. J., and F. D. Panetta. “Eradication of the exotic weeds Helenium amarum (Rafin) HL and Eupatorium serotinum Michx. from south-eastern Queensland.” Proceedings of the 13th Australian Weeds Conference. Perth, Australia: Plant Protection Society of Western Australia, 2002. Accessed 07AUG2023

[3] – Hawke, Richard. A Comparative Study of Joe-Pye Weeds (Eutrochium spp.) and Their Relatives, Chicago Botanic Garden, Plant Evaluation Notes, Issue 37, 2014. Accessed 08AUG2023. Accessed 07AUG2023

[4] – Robertson, Charles. “Flowers and insects; lists of visitors of four hundred and fifty-three flowers.” (1928).

[5] – Ford, Everett J., and J. A. Jackman. “New larval host plant associations of tumbling flower beetles (Coleoptera: Mordellidae) in North America.” The Coleopterists’ Bulletin (1996): 361-368.

[6] – Vandevender, John. “Propagation protocol for production of container Eupatorium serotinum Michx. plants (1+ 0 container plug); USDA NRCS-Appalachian Plant Materials Center, Alderson, West Virginia.” https://www.nrcs.usda.gov/plantmaterials/wvpmcot11379.pdf Accessed 08AUG2023. Archived version-08AUG2023

[7] – Brown, James E., Joe B. Maddox, and Walter E. Splittstoesser. Performance of trees, shrubs, and forbs seeded directly in the fall on minespoil and silt loam soil. Vol. 12. No. 4. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, 1983. Accessed 08AUG2023.

[8] – Eupatorium serotinum Michx., North American Ethnobotany Database. Accessed 08AUG2023.

Joe Foster

Hi - I grew up outdoors in nature - hiking, fishing, hunting. In high school I got my first job at a garden center where I learned to garden and landscape. I've been growing plants from seed and designing native plant gardens for over 10 years. I hope to share some of my knowledge with you! You may have seen some of my videos I create on our YouTube channel, GrowitBuildit (more than 10 million views!). You can find my channel here: https://youtube.com/@growitbuildit Additionally I am a wood worker / DIY enthusiast. I enjoy designing/building projects (with hand tools when I can!). I hope to give you some tips and useful information!

Recent Posts