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Iris virginica Virginia Iris, Blue Flag, Blue Flag Iris

Edward F. Gilman, Ryan W. Klein, and Gail Hansen


Blue flag iris has wonderfully textured, light-green foliage emerging directly from the ground in dense clumps. It grows 12 to 18 inches tall, producing lavender-blue flowers about 4 inches across in the spring. Flowers are displayed in a showy fashion slightly above the foliage. They are native to boggy areas where water stands all year long. They will grow in standing water.

Full Form - Iris virginica: Blue flag, blue flag iris.
Figure 1. Full Form - Iris virginica: Blue flag, blue flag iris.
Credit: Edward F. Gilman, UF/IFAS


Full Form - Iris virginica: Blue flag, blue flag iris.
Figure 2. Flower - Iris virginica: Blue flag, blue flag iris.
Credit: Edward F. Gilman, UF/IFAS

General Information

Scientific name: Iris virginica

Pronunciation: EYE-riss vur-JIN-nick-uh

Common name(s): Virginia iris, blue flag, blue flag iris

Family: Iridaceae

Plant type: herbaceous; ornamental grass; aquatic plant

USDA hardiness zones: 8B through 11 (Figure 3)

Planting month for zone 8: year-round

Planting month for zone 9: year-round

Planting month for zone 10 and 11: year-round

Origin: native to Florida

Invasive potential: aggressive, spreading plant

Uses: border; mass planting; container or above-ground planter; naturalizing; water garden; accent

Availability: somewhat available, may have to go out of the region to find the plant

Shaded area represents potential planting range.
Figure 3. Shaded area represents potential planting range.


Height: 4 to 7 feet

Spread: 1 to 3 feet

Plant habit: upright

Plant density: moderate

Growth rate: moderate

Texture: coarse


Leaf arrangement: most emerge from the soil, usually without a stem

Leaf type: simple

Leaf margin: entire

Leaf shape: linear

Leaf venation: parallel

Leaf type and persistence: evergreen

Leaf blade length: 18 to 36 inches

Leaf color: green

Fall color: no fall color change

Fall characteristic: not showy


Flower color: blue

Flower characteristic: spring flowering


Fruit shape: elongated

Fruit length: 0.5 to 1 inch

Fruit cover: dry or hard

Fruit color: green

Fruit characteristic: persists on the plant

Trunk and Branches

Trunk/bark/branches: typically, multi-trunked or clumping stems

Current year stem/twig color: not applicable

Current year stem/twig thickness: not applicable


Light requirement: plant grows in part shade/part sun

Soil tolerances: extended flooding; slightly alkaline; clay; sand; acidic; loam

Drought tolerance: moderate

Soil salt tolerances: poor

Plant spacing: 24 to 36 inches


Roots: not applicable

Winter interest: no special winter interest

Outstanding plant: not particularly outstanding

Pest resistance: long-term health usually not affected by pests

Use and Management

The plant is grown and used for its foliage effect as well as the flower display. The plant flowers for a short period in the spring but the coarse-textured, upright foliage makes this a year-round favorite for a wet garden spot. It is well suited for planting in mass in front of a shrub border, or as a tall ground cover. On 2-foot centers, a thick ground cover can be formed in about 2 years. The individual plants will be nearly indistinguishable by that time.

Although full sun is tolerated if soils stay moist, a well-drained, partially shaded location provides the best habitat for Iris. Plants can be allowed to dry out slightly in a shaded location with little damage to foliage or flowers. As with other irises, over-fertilization will encourage foliage growth at the expense of flowers. A light application once each year should be enough to maintain good growth and a reliable flower display.

Pests and Diseases

No major pest or diseases problems are usually encountered on this iris.

Publication #FPS-288

Release Date:February 12, 2024

Related Collections

Part of Shrubs Fact Sheets

Related Topics

  • Critical Issue: 1. Agricultural and Horticultural Enterprises
Organism ID

About this Publication

This document is FPS-288, one of a series of the Department of Environmental Horticulture, UF/IFAS Extension. Original publication date October 1999. Revised October 2023. Visit the EDIS website at for the currently supported version of this publication.

About the Authors

Edward F. Gilman, professor emeritus; Ryan W. Klein, assistant professor, arboriculture; and Gail Hansen, professor, sustainable landscape design; Department of Environmental Horticulture, UF/IFAS Extension, Gainesville, FL 32611.


  • Gail Hansen de Chapman
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