Southern blue flag iris is a lovely, delicate iris native to the United States and Canada, from the east coast to the middle states as far west as Texas. The genus name Iris is named after the Greek Goddess of rainbows and the species name refers to the state of Virginia where it is found. The common name, "flag", comes from an old English word (flagge) for reeds and refers to its natural preference to wetlands. Reaching a height of 2 to 2.5 feet clumps of bright green, somewhat droopy, strap shaped leaves are topped with light blue to violet flowers borne on naked stems in late spring. The falls are marked with white and can be crested with yellow frill. It does best grown in moist to very wet, humusy to sandy soil and in boggy acidic areas in full sun. Growing even in 6 inches of fresh standing water, it should not be permitted to dry out during the growing season. These iris may be left in water over winter and can be used in pond borders of up to 6 inches deep. It will tolerate light shade in the warmer regions of its range. Southern flag iris spreads slowly by rhizomes which can be divided for propagation as clumps form. This iris is deer resistant. Mass plant this native along a pond margin, water garden, rain garden, or other low lying damp area of the landscape. Insects, Diseases, and Other Plant Problems: No significant problems. Watch for snails and slugs More information on Iris .
Source: NC State Extension Gardener Plant Toolbox ↗Reconciled to full toolbox: matched by slug to slug 'iris-virginica'. Identity (id/common/scientific name) preserved from the original 87-plant Hunnicutt set; attribute data refreshed from the 54-attribute toolbox scrape.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Height: 1 ft. 0 in. - 2 ft. 6 in. | Width: 1 ft. 0 in. - 3 ft. 0 in.
Growth rate
Medium
Maintenance
Low
Canopy layer
4 - Herbaceous (1-3 ft)
Form & Appearance
Habit / form
Clumping
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Rosulate
Leaf shape
Lanceolate; Linear
Hairs present
No
Leaf detail
Strap-like and have a pronounced midrib in the center are not as upright; they may lay over or fall into the water.
Flower color
Blue; Purple/Lavender
Flower shape
Irregular
Flower size
1-3 inches
Flower detail
1 at the top of a naked stem, 6-parted with 3 outer, spreading or pendent "falls" with white marks and yellow crests, and 3 inner, erect "standards", variously colored light blue to violet. Blooms for 2-3 weeks in late spring.
Bloom time
Spring
Fruit type
Capsule
Fruit detail
Displays from July to September.
Wildlife & Ecology
Native status
Native
Origin
Eastern Canada to Central & Eastern U.S.A
Play value
Attractive Flowers
Food & Medicine
Harvest time
Summer
Fruit type
Capsule
Landscape Use
Landscape location
Pond; Riparian; Small Space
Landscape theme
Native Garden; Rain Garden; Water Garden
Design feature
Mass Planting
Garden tags
#riparian #rain garden #pond margins #bulb #native water plant #blue flowers #spreading #purple flowers #water garden #NC native #strappy leaves #deer resistant #wet soils tolerant #Coastal OBL #Piedmont Mountains OBL #butterfly friendly #Audubon #problem for dogs #problem for horses #problem for cats #full sun tolerant #low lying area #flowers late spring #flood tolerant #standing water tolerant #low maintenance #mass planting #small spaces #boggy sites #NC Native Pollinator Plant #pond #wetland #contact dermatitis
Problems & Resistance
Insect problems
Slugs and Snails Found on Flowers and Foliage
Problems
Problem for Cats; Problem for Dogs; Problem for Horses
Resistant to
Deer; Diseases; Wet Soil
Propagation
Division
Poison severity
Low
Poison parts
Roots; Sap/Juice; Seeds
Poison symptoms
CAUSES ONLY LOW TOXICITY IF EATEN. SKIN IRRITATION MINOR, OR LASTING ONLY FOR A FEW MINUTES. Nausea, vomiting, abdominal pain, diarrhea, elevated temperature following ingestion; skin irritation upon contact with seeds, rootstock, or cell sap.