Smooth Ironweed, Vernonia fasciculata

Smooth Ironweed

Vernonia fasciculata

Sun Shade:
Bloom Time: Summer
Zones: 3, 4, 5
Soil Conditions: Clay, Loam, Sand
Soil Moisture: Moist
Color: Purple, Red
Fragrance: No
Height: 4 - 6 feet
Spacing: 2 feet


Smooth Ironweed (Vernonia fasciculata) typically occurs in low moist prairies and in swampy river bottom meadows . This is an upright perennial that typically grows 2-4 feet tall on stiff, leafy stems which branch at the top. Narrow, linear to lance-shaped leaves have serrated margins. Composite flowers, each with dense, fluffy, purple disks (rays absent), bloom in dense, fastigiately clustered, corymbose cymes from late summer into fall.

The blooming period occurs from late summer to early fall, and lasts about a month. The flowers are replaced by achenes that have a pappus of hair-like scales. These achenes can be blown several feet from the mother plant by gusts of wind. The root system is spreading and fibrous.

Habitats include wet to moist black soil prairies, river bottom prairies, marshes, sloughs along railroads, and edges of fields. Smooth Ironweed is found in wetland habitats to a greater extent than other species of Ironweeds.

Easily grown in average, medium to wet soils in full sun. Although it is mostly seen growing in the wild in moist soils, with tolerance for periodic but brief flooding, it performs quite well in cultivation in average garden soils. Plants generally grow taller in moist soils. Ironweed can be started outdoors with fall planting or after two months of moist-cold stratification. This species of ironweed tends to hybridize with other native ironweeds, which can sometimes complicate plant identification.

Plant Notes and Herbal Uses
  Flowers are very attractive to butterflies.
  Overall plant height may be reduced by cutting back stems in late spring.
  Easily grown from seed.
  Remove flower heads before seed develops to avoid any unwanted self-seeding.
Further Information

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