Flag Iris

The Iris is one of the most popular perennials and is available in a variety of colors with varying blooming times. The family Iridaceae is a very large one of perennial herbaceous herbs growing from a rhizome, corm, or bulb. There are Iris varieties native throughout the world that offers the possibility of use in a native or woodland garden. 

The native habitats of the Iris range from North America, Europe, Africa, and Asia. They grow in meadows, deserts, mountain ranges, hillsides, and along streams. 

In Greek mythology, Iris is the Goddess of the Rainbow. The genus name, Iris, is from the Greek word for "rainbow' and is aptly named because of the variety of flower colors available. The genus has about 300 species and thousands of cultivars.

Different varieties require light from full sun to full shade. Neutral to alkaline soils are required for some species. They grow in mounds or drifts in rich soils; some prefer wet or marshy areas and even standing water.  Some can be grown as houseplants. They propagate through root division or by seed. Some varieties require rhizomes to be at soil level, while others tolerate planting corms and bulbs deeper in the soil. Most iris require periodic division of the rhizomes.  After blooming is complete, allow the foliage to deteriorate and then remove the spent foliage. 

The leaves tend to be long, strap-like, and sword-shaped, overlapping at the base, and oriented in one plane.  The flowers may be a single to several blooms. They are carried at the top of a naked stem. The stem can be as short as 3 inches in dwarf varieties to as tall as 3 feet. The showy blooms are 6-parted with three often distinctly marked outer, spreading, or pendant "falls" and three inner, erect "standards". The variety of iris colors range from blues to violets to yellows to oranges to white to even black and are prized as cut flowers in the perennial garden. The seeds are carried in a fruit capsule, but the division of rhizome or root is the best propagation method and helps to prevent overcrowding. 

Iris is most effective when planted in small groups or in mass plantings. They may be used as border plantings, foundation plantings, near a patio, and along walkways, woodlands, and meadows. They are perfect for a cutting garden or cottage garden.

Quick ID Hints:

• green sword-like foliage, basal leaves are commonly fan-shaped, leaves are 2-ranked and often flat.
• small to large, showy orchid-like flowers in a variety of colors
• blooms have 3 upright petals known as standards, 3 downward-facing sepals called falls,
• fruit is a brown capsule

Insects, Diseases, and Other Plant Problems:  Potential insect pests include aphids, caterpillars, beetles, snails, slugs, spider mites, thrips, and whiteflies. They are susceptible to diseases such as bacterial soft rot, botrytis blight or gray mold, leaf spots, root and crown rots, rust, and viruses. 

To learn more about individual species, see the boxes below.

VIDEO created by Andy Pulte for “Landscape Plant Identification, Taxonomy, and Morphology” a plant identification course offered by the Department of Plant Sciences, University of Tennessee.