Giant Ironweed
Vernonia gigantea
- Plant Type
- Wildflower (Deciduous)
- Landscape Layer
- Tall Herbaceous
- Sun
- ☀️ Full Sun, ⛅ Part Sun, ☁️ Shade
- Moisture
- 💧 Regular
- Soil
- Clay, Loam, Sand, Silt, Rocky / Acidic
- Bloom
- August, September, October
- Sociability
- S2 – Small groups
Pollinator Value
- 🐝 Specialist Bee Host
- Melissodes denticulatus, Melissodes dentiventris, Melissodes druriellus, Melissodes boltoniae, Melissodes niveus, Melissodes subillatus, Svastra obliqua, Megachile inimica, Megachile xylocopoides
S17 Asteraceae specialists listing Vernonia as host genus; ranges include NY/PA/ON
Ecology & Conservation
- Proximity Score
- 1
- Native Status
- ❌ Outaouais ❌ Ottawa ❌ QC ✅ ON
- Closest Direction
- S
- CEC Eco-Regions
- 8 – Eastern Temperate Forests, 8.1 – Mixed Wood Plains, 8.1.1 – Eastern Great Lakes and Hudson Lowlands
- Rarity Notes
- Globally secure (G5) but critically imperiled in Ontario (S1), where it is restricted to a few sites in the extreme southwest near Windsor and Lake St. Clair. Canadian national rank is N1. Not listed under SARA or COSEWIC. Ontario herbarium specimens are from Windsor, Walpole Island, Lake St. Clair, Jeanette's Creek, and Bothwell, all in the Carolinian zone.
- Rarity Ranks
- QC SNA – Not Applicable, ON S1 – Critically Imperiled
- Migration
- Stable
- Ecological Context
- Giant ironweed occupies moist to mesic habitats in the Eastern Temperate Forests, favoring open woodlands, woodland borders, thickets, swamps, riverbottom prairies, seeps, and abandoned fields. In Ontario it is critically imperiled (S1), restricted to the extreme southwest near Windsor and Lake St. Clair. It tolerates occasional disturbance and is found in wooded areas more than other ironweed species, though it also colonizes moist open ground.
Permaculture & Companion Planting
- Roles
- Insectary Plant, Pollinator Attractor
S73/S29/S72 Evidence: Insectary Plant: S64 NPPBI 'beneficial insects' flag] | Pollinator Attractor: S73 [HIGH]: S64 Xerces listed (source-classified)]
- Notes
- Giant ironweed pairs well with moisture-loving sedges and grasses in rain gardens and wetland edges. Its tall stature and late-season bloom complement earlier-flowering species. Tolerates juglone, making it suitable near black walnut.
Edibility & Foraging ℹ
Never ingest a plant unless you have 100% certainty of its identity and have consulted multiple reputable sources. The information provided in the Localeaf Plant Database is compiled from secondary sources for educational and historical purposes only.
Click here for more info →
ℹ
Never ingest a plant unless you have 100% certainty of its identity and have consulted multiple reputable sources. The information provided in the Localeaf Plant Database is compiled from secondary sources for educational and historical purposes only.
Click here for more info →❌ Not Edible
Seed Source
- Localeaf
- OWSL