Giant Ironweed



Botanical Name:  Vernonia gigantea

Common Name:  Giant Ironweed

Description:  Looking for a very cool, very tall native perennial wildflower with dark lavender/purple flowers?? Then Giant Ironweed could be for you!

Giant Ironweed is a robust, perennial wildflower found naturally in floodplains, wet to mesic pine flatwoods and ruderal areas, and along forest margins and stream banks in Florida. Flowering occurs in large masses in summer and fall, with peak blooming in July. The flowers bloom at the tops of the plants, which means they can be seen over shorter plants. It attracts many pollinators, particularly butterflies and native bees. The nectar also attracts hummingbirds. Is the larval host plant for Spring Azure Butterfly. It likes to grow in moist to moderately dry, well-drained sandy and loamy soils in sun, part sun, or part shade. Quickly grows up to 10′ tall, so put it in the back of the garden. Can also use on the edges of natural or created wetlands and streams. Not very drought tolerant. Is deer resistant. Livestock doesn’t eat it. This plant can sucker and grow into thickets, but the seedlings are easily removed if needed. It is deciduous and will die back in the winter. Deadheading of the spent blooms will encourage continued flowering.

Unlike most members of the Aster family, the giant ironweed flower lacks ray florets. Its disc florets are tubular and may be lavender, magenta or deep purple. Extending from within each disc floret tube is a bifurcated and curled style. The flowers are about 1 inch in diameter and are born in loose terminal panicles. At the base of each flower are bracts that vary in color from dark green to purplish-green to brown. Basal leaves are coarse, oval-shaped and appear in early spring. Stem leaves are narrowly ovate to elliptic and can grow up to 8 inches long. Both have serrated margins. Stems may be glabrous or finely pubescent. Seeds are tiny achenes with tufts of bristles that catch the wind and aid in dispersal.

Not salt tolerant of inundation by salty or brackish water. Some tolerance to salty wind but not direct salt spray.

This plant in 1-gallon containers is 2-3′ tall.

Plant Lore: The common name, ironweed, may refer to the toughness of the stem of this and other Vernonia species. The species name, gigantea, is Latin and means “of giants.”

Hardiness Zones 5 – 10


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