Tall Ironweed
Vernonia gigantea (Walter) Trel.
- light
- Sun–part
- water
- Medium
- tall
- 1.5 m
- wide
- 1.4 m
Asteraceae
Also called Giant Ironweed, Giant ironweed
Formerly Cacalia gigantea, Chrysocoma gigantea, Chrysocoma praealta, Serratula altissima, and 5 more
When it flowers
Not known yet in the tropics: too few flowering observations to read a season from.
Read from iNaturalist photographs of it in flower. A month counts at 50% of the best month's flowering share (smoothed over three months) and 10% of its flowering count, from at least 100 flowering observations in the band.
If a child, a pet or anyone may have eaten a plant, contact a doctor or vet straight away, or call the National Poisons Information Centre (AIIMS, New Delhi) on 1800 116 117, free and open 24 hours.
Something wrong with it?About it
- Grows as
- PerennialKew's checklist, not yet checked
- Climate
- TemperateKew's checklist, not yet checked
- Wild in
- SE. Canada to C. & E. U.S.A.Kew's checklist, not yet checked
- Light
- Full sun to part shade (3 h or more)Read from NC State Extension, one source
- Height
- 91 cm to 2.1 mRead from NC State Extension and Wikipedia, checked by a majority of its sourcesBacked by both sources. Sources differ: NC State Extension 3–12 ft; Wikipedia 0.9–2.1 m
- Spread
- 91 cm to 1.8 mRead from NC State Extension, one source
- Water
- Average: moist, well drainedRead from NC State Extension, one source
- Flowers
- PurpleRead from NC State Extension and Wikipedia, checked by a majority of its sourcesBacked by both sources
- Coldest it survives
- -28.9 °C (USDA zone 5a)Read from NC State Extension, one source
Not known yet: heat, hottest it survives.
In other languages (5)
- French
- vernonie géante
- Russian
- Вернония гигантская
- Chinese (China)
- 巨斑鸠菊
- Chinese
- 巨斑鳩菊
- Slovak
- vernónia najvyššia
Where this comes from
- iNaturalist, read 2026-10-25, CC0-1.0 (observation counts)
- Wikidata, read 2026-10-25, CC0-1.0
- Kew's checklist, read 2026-10-24, CC-BY-4.0
- NC State Extension, read 2026-10-25, fact, cited
- Wikipedia, read 2026-10-25, fact, cited
- Wikimedia Commons, read 2026-10-25, Public domain
- iNaturalist, read 2026-10-25, CC BY
- iNaturalist, read 2026-10-25, CC BY
- iNaturalist, read 2026-10-25, CC BY
- 3D model: Vernonia gigantea (built for Vanagrha) by Vanagrha, own
A fact “checked by a majority of its sources” was settled by a vote of the pages it was read from, not by a person reading it; one marked “one source” rests on that page alone. Anything else not marked checked has not been checked yet. Where nothing is known, the page says so rather than guess.