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Iron Butterfly Ironweed

Vernonia lettermannii (ver-NON-ee-uh let-ter-MAH-nee-eye)

Family: Asteraceae Unknown Herbaceous (3-15 ft)

Iron butterfly ironweed is an ironweed cultivar that is grown for its mounding habit and showy long-lasting bright purple-violet flowers. This cultivar was created to accentuate a compact habit, rapid growth rate, and long bloom period. It grows to a height of 24 to 36 inches tall and 18 to 24 inches wide. It is a member of the Asteraceae family. The genus name, Vernonia , honors an English botanist, William Vernon. The epithet, lettermanii, honors, an American botanist, George W. Letterman. The plant is dense and multi-branched, and the foliage is fine and thread-like. Many frilly aster-like or disc flowers appear in summer at a time when other flowers are giving out to provide the bees and butterflies with nectar. They will flock to this plant! The foliage is attractive even when not in bloom, adding a finer texture to the garden. Grow this plant in average well-drained soils in full sun to light shade. It is drought tolerant once established and poor soil tolerant so do not over-fertilize. It is recommended to cut this plant back early in the season to prevent the stems from flopping over. Seedlings of this plant are taller with bigger and bolder leaves. To prevent seedlings from developing, trim the flowers as they go to seed. Leave the stems intact during the winter and cut to the ground in late winter or early spring. Use the iron butterfly ironwood to add texture and color to the late-season garden. Consider using this plant in a rock garden, drought-tolerant garden, or as a border in a pollinator garden. Quick ID Hints: grows 24 to 36 inches tall and 18 to 24 inches wide, dense, and multi-branched foliage fine, thread-like aster-like flowers of bright purple violet in late summer Insects, Diseases, and Other Plant Problems: This cultivar has no serious insect or disease problems. The stems may bend and flop over if planted in soil that is too rich or if the plant obtains too little sun. VIDEO created by Andy Pulte for “Landscape Plant Identification, Taxonomy and Morphology” a plant identification course offered by the Department of Plant Sciences, University of Tennessee. More information on Vernonia lettermannii .

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 48 attributes.

How it fits the guild

Guild layer 4 - Herbaceous (3-15 ft) Optimal soil pH Acid (<6.0); Alkaline (>8.0); Neutral (6.0-8.0)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Fills a similar niche Echinacea purpurea PowWow® Wild Berry 'PAS702917' Lantana camara Bandito™ Group Salvia rosmarinus

Full plant profile

Growing Conditions
Plant type
Herbaceous Perennial; Perennial
Life cycle
Perennial
USDA zones
4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Light
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand; Shallow Rocky
Soil pH
Acid (<6.0); Alkaline (>8.0); Neutral (6.0-8.0)
Soil drainage
Good Drainage | Occasionally Dry
Available space
12 inches-3 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 3 ft. 0 in. | Width: 1 ft. 6 in. - 2 ft. 0 in.
Growth rate
Rapid
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Dense; Mounding; Multi-stemmed
Texture
Fine
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Linear
Leaf margin
Entire
Leaf value
Showy
Leaf size
3-6 inches long, < 1 inch wide
Hairs present
No
Leaf detail
Attractive linear green leaves spiral alternately up the stem and become denser at the tips. Up to 5 inches long and 1/8 inch wide with smooth margins.
Flower color
Purple/Lavender
Flower value
Long Bloom Season; Showy
Flower form
Corymb
Flower size
< 1 inch
Flower detail
Frilly 1-inch purplish-red disc flowers in terminal corymbs in mid to late summer from July to August.
Bloom time
Summer
Stem color
Green
Wildlife & Ecology
Native status
Unknown
Origin
Cultivar of a native plant
Attracts
Bees; Butterflies; Pollinators
Play value
Attractive Flowers; Attracts Pollinators; Colorful
Landscape Use
Landscape location
Pool/Hardscape; Slope/Bank
Landscape theme
Butterfly Garden; Cottage Garden; Drought Tolerant Garden; Pollinator Garden; Rock Garden
Design feature
Border
Garden tags
#long bloom time #fast growing #pollinator plant #showy flowers #rock garden #drought tolerant #fine texture #magenta flowers #butterfly friendly #landscape plant sleuths course #summer flowers #perennial #compact #poor soil tolerant #moth friendly
Problems & Resistance
Resistant to
Drought; Dry Soil; Erosion; Poor Soil

Planted at Hunnicutt

Nobody’s planted this one yet.