Simcoe County Master Gardeners
Grow Natives!
PLANT PROFILE
COMMON NAME: Tall Ironweed, aka Giant Ironweed
BINOMIAL: Vernonia gigantea
| Family | Asteraceae (Aster Family) |
| Cdn Native Range | Ontario |
| Natural habitat | damp areas in fields or along forest edges and streams |
| Type | herbaceous perennial |
| Features | showy bright magenta flowers that bloom late summer to early fall. nectar-rich flowers attract a variety of native bees and butterflies |
| Growth habit | tall, upright, strong stems which branch out at the top |
| Mature height | 90 – 210 cm (3 – 7 feet) |
| Mature spread | 90 – 150 cm (3 – 5 feet) |
| Life span | perennial |
| Cdn Hardiness Zone | 5 – 8 |
| Growing conditions | full sun to part shade |
| Soil conditions | soil containing loam, clay loam, silt loam or sandy loam |
| Watering needs | moist to medium |
| Fertilizer needs | n/a |
| Tolerance | tolerance for periodic flooding, but performs quite well in average garden soils; the bitter foliage it is seldom eaten by deer or other herbivores |
| Maintenance rank | low |
| Maintenance needs | plant height may be reduced by cutting back stems in late spring. remove flower heads to avoid unwanted self-seeding |
| Bloom | clusters of vivid purple flowers on top of strong stems in late summer to early fall; rust-coloured seed heads persist throughout the winter months |
| Fruit | n/a |
| Pollinator support | a variety of native bees and butterflies; some bees collect pollen for their larvae |
| Environmental support | butterfly larva host plant for crossline skipper, painted lady, American lady. moth larva host plant for eupatorium borer moth, parthenice tiger moth, ironweed borer moth, red groundling, ruby tiger moth, ironweed root moth, ironweed moth |
| Garden Use | back of the border; accent; fence line; winter interest; pollinator gardens; cut flower |
| Risks & Cautions | none |
References: Rick Gray and Shaun Booth. The Gardener’s Guide to Native Plants of the Southern Great Lakes Region. Firefly Books, 2024; Missouri Botanical Garden Plant Finder, www.missouribotanicalgarden.org/plantfinder/plantfindersearch.aspx
Photo Credits:
Giant Ironweed – whole plant and flowers (credit: Nennieinszweidrei by Pixabay)
Giant Ironweed – seed heads (credit: Nennieinszweidrei by Pixabay)
