Perennial
Giant Ironweed
Vernonia gigantea
Varieties We Carry
VeronicaVernonia giganteaStandardVernonia gigantea
Sizes & Pricing
1 galFrom$7.95
3 galFrom$19.95
Fresh this week. Last restocked Mar 11.
LightFull Sun, Part Sun
WaterModerate to High
Mature size3-10 feet × 2-4 feet
About Giant Ironweed
Giant Ironweed (Vernonia gigantea) is a Florida-native perennial wildflower reaching 3–10 feet tall, producing vivid purple-magenta flower clusters from July through October. Hardy throughout zone 9b (zones 8b–10b), it is an excellent pollinator plant for naturalistic gardens, meadows, and rain garden settings in NE Florida. Starting at $7.95.
Plant details
- Bloom Season
- Summer, Fall
- Flower Color
- Purple
- Growth Rate
- Fast
- Foliage
- Deciduous
- Soil
- Loam, Clay, Well-drained, Wet
Best planting months
Recommended forZone 9b · St. Augustine, FL
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This monthGood windowOther months
Seasonal care
New foliage emerges. Good planting window.
Bloom season.
Bloom season. Foliage may begin to change or drop. Ideal planting window.
Dormant — drops foliage.
Care essentials
Light
Plant Giant Ironweed in full sun to part sun; it blooms most prolifically in full sun. In NE Florida, it thrives in open meadow settings and naturalistic borders with at least 6 hours of direct light daily.
Water
Prefers moderate to consistently moist soil; tolerates periodic wet conditions and clay. In NE Florida, it grows well in rain garden settings and low areas where summer rains naturally accumulate.
Soil & Fertilizer
Adaptable to a wide range of soils including clay, loam, and moist areas. Little to no fertilizer needed—this native thrives in average to poor soil, and over-fertilizing promotes excessive height and flopping.
Similar needs
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Scarlet Rosemallow
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Hardy Hibiscus
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American Hornbeam
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Common questions
Is Giant Ironweed a good plant for St. Augustine?
Giant Ironweed is a perennial for Zone 9b coastal Florida gardens, reaching 3-10 feet × 2-4 feet.
Care information verified from
Last reviewed February 2026. Our care guidance comes from trusted horticulture sources and decades of helping St. Augustine gardeners. Conditions here can vary dramatically from one area to the next, so come ask us and we'll tailor it to your yard.