Tall Thoroughwort
Eupatorium altissimum
Last reviewed: September 2026
Tall thoroughwort is a full sun perennial forb that blooms with small white flower clusters from July through September, growing well in dry to medium prairies, fields, and open woodland edges.
Toxicity unknown
Tall Thoroughwort (Eupatorium altissimum) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.
Light
full sun
Water
medium
Size
36"–72" H × 12"–24" W
Bloom
Jul, Aug, Sep
Native to
AL, AR, CT, FL and 26 more states
Pollinators
bees, butterflies, wasps, beetles
Before you buy
Your city may pay you to plant this
Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.
Find rebates in your areaBrowse plants for this ecoregion
Tall thoroughwort is a native perennial that forms upright clumps with clusters of small white flowers from summer through early fall. This sturdy plant grows 3-6 feet tall with a narrow spread, making it useful as a vertical accent in gardens.
Growing Tall Thoroughwort
Grow Tall Thoroughwort in full sun and medium water. Mature plants reach 36 to 72 inches tall and spread 12 to 24 inches wide. Expect low maintenance to keep it looking intentional in a front yard.
In an HOA neighborhood
Tall Thoroughwort takes more care to keep looking intentional in a front yard. Maintenance level: low. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Height can appear overgrown in formal settings
- May look weedy when not in bloom
- Common name includes 'wort' which sounds undesirable
Wildlife value
The late-season blooms provide important nectar for bees, butterflies, and other pollinators when many other flowers have finished. Seeds also feed birds in fall and winter.
Common questions
- When does Tall Thoroughwort bloom?
- Tall Thoroughwort typically flowers from July through September, producing small clusters of white blooms.
- What pollinators visit Tall Thoroughwort?
- Bees, butterflies, wasps, and beetles are commonly seen visiting the flower clusters for nectar and pollen.
- How much sun does Tall Thoroughwort need?
- It grows best in full sun but can tolerate part sun and part shade, especially at woodland edges.
- How much water does Tall Thoroughwort need?
- It prefers medium soil moisture but adapts to drier conditions, which suits its typical prairie and open field settings.
- Is Tall Thoroughwort HOA-friendly?
- Tall Thoroughwort takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.
These answers were drafted with an AI model from this plant's data. Verify care details with a local expert.
Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
If something looks wrong
Common plant problems, and what to check first
These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.
- It is dying right after planting
- Leaves turning yellow
- Wilting even though I watered it
- Brown crispy leaf tips
- Bugs on the plant
Ready to grow Tall Thoroughwort? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.
Planning a bed around it? Start a free plan with this plant
Not sure where to start? Take the 2-minute yard quiz