Blue flag (Iris versicolor)

Blue flag

Features and Characteristics

Iris veriscolor, commonly called northern blue flag, is a clump-forming iris that is native to marshes, swamps, wet meadows, ditches and shorelines from Manitoba to Nova Scotia south to Virginia, Ohio, Illinois and Minnesota. It is a marginal aquatic plant that forms a clump of narrow, arching-to-erect, sword-shaped, blue-green leaves (to 24” long and 1” wide). Flowering stalks rise from the clump to 30” tall in late spring, with each stalk producing 3-5 bluish-purple flowers (to 4″ wide) with bold purple veining. Falls (sepals) have a central yellow blotch surrounded by a white zone. Clumps spread slowly by tough, creeping rhizomes. Northern blue flag thrives in wetland habitats frequented by rushes and sedges (the “flag” part of the common name comes from the middle English word flagge meaning rush or reed). Rhizome is poisonous.

Genus named for the Greek goddess of the rainbow.

Specific epithet means having various colors.

Care and Maintenance

Grow in medium to wet soils in full sun to part shade. This iris may be grown in up to 2-4” of shallow standing water (muddy bottom or containers), or in moist shoreline soils or in constantly moist humusy soils of a border. Propagate by division after bloom. Wear gloves when dividing the rhizomes. After fall frost, plant leaves may be trimmed back to about 1” above the crown. Will naturalize to form colonies in the wild.

Blue flag (Iris versicolor) Requirements

Hardiness zone	3 - 9
Sun light	Full sun to part shade
Water	Medium to wet
Maintenance	Low

Common Problems

Susceptible to a number of insect pests including iris borer, iris thrips, and aphids. Potential disease problems include various rots (rhizome rot, crown rot, bacterial soft rot) leaf spot, and leaf/blossom blight. Aphids can spread mosaic virus.

Uses

Best grouped in sunny areas of ponds or water gardens. Also may be grown in moist border areas.

Blue flag (Iris versicolor) Details

Common name	Blue flag
Botanical name	Iris versicolor
Plant type	Herbaceous perennial
Family	Iridaceae
Hardiness zone	3 - 9
Water	Medium to wet
Maintenance	Low
Flower color	Violet blue
Flowering period	May - June
Height	2 - 2.50 feet
Width	2 - 2.50 feet