Blue Flag Iris
Iris versicolor
A native North American wetland iris with striking violet-blue flowers veined in yellow and white. It thrives in marshes, pond margins, and wet meadows.
- Light
- Full sun to partial shade
- Water
- High; wet soil or shallow water
- Difficulty
- Easy
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Overview
Blue flag iris is a robust native perennial of eastern North American wetlands, prized for its showy blue-violet blooms. It grows from a thick rhizome and forms handsome clumps of upright, sword-shaped leaves.
Unlike the invasive yellow flag iris, blue flag is a well-behaved native that supports local pollinators and stabilizes wet soils. Its name "flag" derives from an old word for rush or reed, referring to its waterside habitat.
How to identify it
- Flowers: Violet-blue, 2-4 inches across, with downward-arching falls veined yellow and white and a yellow signal patch
- Leaves: Sword-shaped, gray-green, in a fan, 2-3 feet tall
- Stems: Stout flowering stalks often branched, bearing several blooms
- Rhizome: Thick, creeping underground stem
- Bloom time: Late spring to early summer
Care & growing
Blue flag iris is easy in consistently wet conditions.
- Light: Full sun to partial shade
- Water: Wants wet soil and tolerates standing water up to a few inches deep; ideal for pond edges and rain gardens
- Soil: Rich, moist to wet, slightly acidic soil
- Temperature: Very hardy, USDA zones 3-9
- Feeding: Generally unnecessary in fertile wetland soil
- Propagation: Division of rhizomes after flowering, or by seed
Habitat & origin
Iris versicolor is native to eastern North America, from Canada south through the northeastern and north-central United States.
It grows naturally in marshes, swamps, wet meadows, ditches, and along the shorelines of ponds, lakes, and slow streams. It is a classic component of native wetland and shoreline plant communities.
Frequently asked questions
Can blue flag iris grow in standing water?
Yes, it tolerates shallow standing water of a few inches and thrives at pond and stream margins, making it ideal for water and bog gardens.
Is it the same as yellow flag iris?
No. Yellow flag (Iris pseudacorus) is a non-native, invasive species. Blue flag (Iris versicolor) is a well-behaved North American native with blue-violet flowers.
How do I propagate blue flag iris?
The easiest method is dividing the rhizomes after flowering; it can also be grown from seed that benefits from cold stratification.
Blue Flag Iris guides
In-depth guides for identifying, growing, and caring for Blue Flag Iris.
