Blue flag
Iris versicolor
Last reviewed: August 2026
Blue flag (Iris versicolor) is a perennial forb native to CT, MA, MD, ME and 11 more states. It blooms in May, June, and July. The flowers draw bumble bees, syrphid flies, and hummingbirds.
Blue flag is toxic to dogs and cats.
Listed as toxic by the ASPCA Animal Poison Control Center (opens in new tab) (last reviewed 2026-08-15). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435and your veterinarian's emergency line.
Pollinator Patch flags toxic plants so you can choose a pet-safe native alternative for your yard.
Light
full sun
Water
high
Size
24"–36" H × 18"–24" W
Bloom
May, Jun, Jul
Native to
CT, MA, MD, ME and 11 more states
Pollinators
bumble bees, syrphid flies, hummingbirds
Before you buy
Your city may pay you to plant this
Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 445 programs across 44 states, each with a link to the provider and the date we last checked it.
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A wetland iris with broad sword-shaped leaves and violet-blue flowers veined in yellow and white. It thrives in saturated soil at pond edges and in rain gardens, forming slow-spreading clumps from thick rhizomes.
Growing Blue flag
Grow Blue flag in full sun and high water. Mature plants reach 24 to 36 inches tall and spread 18 to 24 inches wide.
Wildlife value
A reliable early-summer nectar source for large bees, and the dense foliage clumps shelter amphibians at water margins.
Common questions
- How much sun does Blue flag need?
- Blue flag grows best in full sun conditions.
- When does Blue flag bloom?
- Blue flag blooms in May, June, and July.
- Where is Blue flag native?
- Blue flag (Iris versicolor) is native to CT, MA, MD, ME and 11 more states, per the World Checklist of Vascular Plants (Kew).
- Is Blue flag toxic to dogs?
- Yes. Blue flag is listed as toxic to dogs by the ASPCA Animal Poison Control Center (aspca.org). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
- Is Blue flag toxic to cats?
- Yes. Blue flag is listed as toxic to cats by the ASPCA Animal Poison Control Center (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
- What pollinators does Blue flag attract?
- Blue flag draws bumble bees, syrphid flies, and hummingbirds.
Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
Pollinator Patch flags toxic plants like Blue flag and shows pet-safe natives for your ecoregion instead.
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