Virtues:Vernonia ‘Southern Cross’, a hybrid ironweed, provides a dense, textural green backdrop to other garden plants all summer, and then extends the garden’s season when it bursts into bright bloom in late summer and early fall. The flowers are excellent for pollinators.
Common name: ‘Southern Cross’ ironweed
Botanical name:Vernonia ‘Southern Cross’
Exposure: Full sun
Season: Late summer and autumn, for flowers
Flowers: Frizzy, bright purple blossoms open atop the stems from late summer into early fall.
Foliage: Threadlike, medium green leaves line the upright stems, providing fine texture reminiscent of Arkansas bluestar and threadleaf coreopsis.
Habit:Vernonia ‘Southern Cross’ grows to about four feet tall and wide, a mass of upright stems covered with short, slender leaves. It has a dense, upright shape overall.
Origins: ‘Southern Cross’ is a hybrid between Vernonia lettermanii and an unknown species. It was discovered by Brent Horvath of Intrinsic Perennials. Vernonia lettermanii is native to western Arkansas and eastern Oklahoma, where it grows in gritty soil and rock crevices above the Ouachita River.
How to grow Vernonia ‘Southern Cross’: Site this perennial plant in full sun and any type of soil that has good drainage. It requires consistent moisture while it is getting established in the garden, but after its first season it grows best kept on the drier side. Cut the previous year’s growth down to just above the ground in earliest spring. USDA Zones 4–9.
Image credit: Walters Gardens