Articles

Rain Garden Plants: Blue Flag Iris

One-page informational sheet with details and pictures of blue flag iris (Iris versicolor).
Updated:
August 18, 2021

Blue flag’s swordlike leaves emerge from thick, horizontal rootstock (corm), which is covered with fibrous roots. Flowering stalks produce three to five showy flowers. Minor skin irritation can occur upon contact with seeds or cell sap. Attracts hummingbirds. Foliage is unpalatable to deer and other herbivores.

Height: 24 to 30 inches
Bloom color: Blue, purple
Bloom time: May to June
Hardiness zones: 4 to 9
Salt tolerance: Moderate
Spreading habit: Spreads by self-seeding and extension of rhizomes

Blue flag iris blossom
Blue flag iris. Photo credit: Jodi Sulpizio, Penn State Extension

Site Conditions

Sun: Sun/partial shade
Soil: Organic, acidic (pH < 6.8)
Hydrologic zones: Wet/moist, 0 to 6 inches, can tolerate complete submergence

Seed pod of blue flag iris
Seed pod. Photo Credit: Sandy Ulrich, York County Master Gardener

Source

Lady Bird Johnson Wildflower Center

Prepared by Jessica Chou, Jodi Sulpizio, and Constance Schmotzer.