When does blue flag iris bloom?

Iris versicolor typically flowers from May through July, with exact timing shifting slightly depending on local spring temperatures and site moisture.

What pollinators visit blue flag iris?

Bumble bees and syrphid flies are the main pollinators working the flowers for nectar and pollen, and hummingbirds will also visit for nectar.

How much water does Iris versicolor need?

This iris grows best in consistently wet to moist soil and tolerates standing water, making it a good fit for pond margins, rain gardens, and low spots that stay damp.

How much sun does blue flag iris need?

It flowers most heavily in full sun but will still grow and bloom, though less vigorously, in part sun with a few hours of shade.

Is Iris versicolor a good choice for a rain garden?

Yes, its tolerance for saturated soil and standing water makes it well suited to rain gardens, pond edges, and other spots that flood periodically.

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.

Blue flag

Name: Pollinator Patch
Author: Pollinator Patch

Iris versicolor

Last reviewed: November 2026

Iris versicolor, or blue flag, is a wetland forb that blooms blue-violet from May through July in marshes, ditches, and pond edges across the northeastern and upper midwestern United States.

Watering reminders and freeze alerts for Blue flag, free in the app.

Blue flag (Iris versicolor) — Photo: (c) Jacek Pietruszewski, some rights reserved (CC BY), uploaded by Jacek Pietruszewski

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) 426-4435 and your veterinarian's emergency line.

The Pollinator Patch App flags toxic plants so you can choose a native alternative that is not on the ASPCA toxic plant list.

Native swaps for a yard with pets

Blue flag is listed as toxic to dogs by the ASPCA Animal Poison Control Center. These natives fill a similar role in a planting and are not on the ASPCA toxic plant list for dogs or cats. Each plant's page carries its dated record.

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

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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

When does blue flag iris bloom?: Iris versicolor typically flowers from May through July, with exact timing shifting slightly depending on local spring temperatures and site moisture.
What pollinators visit blue flag iris?: Bumble bees and syrphid flies are the main pollinators working the flowers for nectar and pollen, and hummingbirds will also visit for nectar.
How much water does Iris versicolor need?: This iris grows best in consistently wet to moist soil and tolerates standing water, making it a good fit for pond margins, rain gardens, and low spots that stay damp.
How much sun does blue flag iris need?: It flowers most heavily in full sun but will still grow and bloom, though less vigorously, in part sun with a few hours of shade.
Is Iris versicolor a good choice for a rain garden?: Yes, its tolerance for saturated soil and standing water makes it well suited to rain gardens, pond edges, and other spots that flood periodically.
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.

These answers were drafted with an AI model from this plant's data. Verify care details with a local expert.

Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

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