Vernonia lettermannii 'Iron Butterfly'

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.