Vernonia. Commonly called Ironweed, this genus includes about 1,000 species of perennials, shrubs and trees native to North America. The plant supposedly gets its common name from the fact that it has tough, erect stems and rusty looking seed clusters as flowers age. Most species can tolerate clay soil. In this feature I will zoom in on perennial Ironweed and five outstanding species sold at garden centers and online. All of these superstars are highly attractive to butterflies.
Vernonia lettermannii. Commonly called narrowleaf ironweed. The plants stature and fine-textured, willowy foliage look similar to Amsonia hubrectii (another great native perennial) but Amsonia blooms in the spring and narrowleaf Ironweed blooms late summer and fall. Both are outstanding pollinator plants. Two popular cultivars are ‘Iron Butterfly’ (2’-3’ tall, pictured right, photo compliments of Bluestone Perennials) and ‘Southern Cross’ (3’-4’+ tall). Narrowleaf Ironweed does best in full sun and is hardy in Zones 4 – 9. If you prefer this beauty to remain more compact, simply shear it back by half in the early part of July.
Vernonia fasciculata. Commonly known as Prairie Ironweed, this gem grows between 3’-6’ tall. It enjoys sun to part sun and starts blooming in mid-summer. This species is a host plant for the American Painted Lady butterfly and is listed by the Xerces Society as having special value to native bees. It is hardy to Zone 3.
Vernonia noveboracensis Commonly known as New York Ironweed, this is a giant, growing to 7’ (or more) where happy. It blooms in late summer and fall. It tolerates wet soil as well as clay. To create a shorter, more compact plant, shear back the stems almost to the ground in late spring (not a typo). Hardy to Zone 5.
Vernonia lindheimer v. leucophylla Commmonly known as Silver Ironweed. I have yet to grow this one – probably because is only hardy to Zone 6. It has stunning silvery foliage and grows to 3’-4’. It prefers well drained soil and it is heat tolerant (like many silver-leaved plants). Photo compliments of High Country Gardens