University of FloridaSolutions for Your Life

Download PDF
Publication #FPS178

Dietes bicolor Evergreen Iris1

Edward F. Gilman2

Introduction

This clumping, robust perennial has floppy leaves radiating up and out in a weeping pattern (Fig. 1). The flower spikes are topped with 3-inch 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.

General Information

Figure 1. 

Evergreen Iris.


[Click thumbnail to enlarge.]
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 (Fig. 2)
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
Uses: border; mass planting; container or above-ground planter; edging; naturalizing; water garden; accent
Figure 2. 

Shaded area represents potential planting range.


[Click thumbnail to enlarge.]
Availability: generally available in many areas within its hardiness range

Description

Height: 2 to 4 feet
Spread: 2 to 3 feet
Plant habit: upright
Plant density: moderate
Growth rate: slow
Texture: fine

Foliage

f 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

Flower color: yellow
Flower characteristic: flowers periodically throughout the year

Fruit

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

Culture

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

Other

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
Invasive potential: not known to be invasive
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-degrees 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.

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

Pests and Diseases

No diseases are of major concern.

Footnotes

1.

This document is FPS178, one of a series of the Environmental Horticulture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date October 1999. Revised June 2007. Reviewed June 2011. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Edward F. Gilman, professor, Environmental Horticulture Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.