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Dietes bicolor Evergreen Iris

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


This clumping, robust perennial has floppy leaves radiating up and out in a weeping pattern. The flower spikes are topped with 3inch yellow flowers marked with black or orange. Although short-lived (about 2 days), the flowers are produced sporadically throughout the year. Plants grow to 4 or 5 feet tall in standing water, making it ideal for water gardens and wet soil. They reach about 3 feet in soil. Iris is also attractive when used as an accent planted in a shorter groundcover. It has a narrower leaf and a finer texture than Dietes vegeta.

Full Form - Dietes bicolor: Evergreen Iris
Figure 1. Full Form - Dietes bicolor: Evergreen Iris
Credit: Edward F. Gilman, UF/IFAS


Flower - Dietes bicolor: Evergreen Iris
Figure 2. Flower - Dietes bicolor: Evergreen Iris
Credit: Edward F. Gilman, UF/IFAS

General Information

Scientific name: Dietes bicolor

Pronunciation: dye-EE-teez BYE-kull-lur

Common name(s): evergreen iris

Family: Iridaceae

Plant type: herbaceous; ornamental grass

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: not native to North America

Invasive potential: not known to be invasive

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

Availability: generally available in many areas within its hardiness range

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


Height: 2 to 4 feet

Spread: 2 to 3 feet

Plant habit: upright

Plant density: moderate

Growth rate: slow

Texture: fine


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: yellow

Flower characteristic: flowers periodically throughout the year


Fruit shape: elongated

Fruit length: .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: plant has winter interest due to unusual form, nice persistent fruits, showy winter trunk, or winter flowers

Outstanding plant: not particularly outstanding

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

Use and Management

Iris will bloom best on rich, moist soil but will tolerate moderately dry soil conditions, growing in nearly full sun to partial shade. Plants in the full sun appear to do best with frequent irrigation. Cold temperatures (below 25°F) cause leaf browning. These leaves can be removed in the spring to clean up the plant. Otherwise, this iris requires no maintenance except for a light fertilization or two each year. Plants can be easily transplanted to other areas of the landscape.

Propagation is by seed or division of the matted clumps. Whole plants are lifted, and the rhizomes divided every three years or when new plants are needed.

Pests and Diseases

Nematodes are the main pest problem. Scales can cover the foliage and cause a severe problem.

No diseases are of major concern.

Publication #FPS178

Release Date:October 12, 2023

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About this Publication

This document is FPS178, one of a series of the Environmental Horticulture Department, 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