The iris derives its name from the Greek word for rainbow and is an apt title for this garden perennial, which comes in a wide variety of colors: red, pink, orange, yellow, blue, purple, white and even brown and black. Found across climate zones and throughout the world, there are more than 200 iris varieties, ranging in size from 8 inches to 4 feet. Generally considered easy to grow, following a few simple steps can ensure an expanding, blooming garden of color and beauty.
Irises need full sun and well-drained, healthy soil. It may be necessary to add sand to heavy soil to ensure proper drainage. In addition, working organic compost, gypsum or a slow-release fertilizer into the soil can greatly improve your blooms and the health of the rhizomes.
Where to Get Irises
Iris rhizomes can be purchased through online websites, from bulb catalog companies such as Brecks or at your local nursery. However, because they are so abundant in so many areas and because they readily multiply, getting them from existing blooms is an easy and cheap way to go. In addition, separating the mass of rhizome roots is beneficial to the parent plant. Just divide the root system by first digging around the whole plant and working it from the soil. Shake the soil from it and rinse with a hose to distinguish and separate individual rhizomes.
Consult a zoning chart for accuracy regarding when to plant. Generally, irises are planted from late summer to early fall, four to six weeks before frost. Loosen the soil beneath where you will plant the rhizomes to a depth of 12 inches, and then build a soil mound. Center the rhizome and spread its roots evenly, covering it with soil so that it is buried, but just beneath the surface. Firm the soil around each rhizome and water thoroughly. Allow 12 to 24 inches between each plant.
Once the plants have yielded flowers, they are established and require little in the way of regular maintenance. Fertilize in the early spring to a soil pH level of 6.8 to 7.0. Bonemeal and superphosphate are good iris fertilizers. Weed appropriately and separate the plants every two to three years to ensure continued blooms and spread.
Pests and Diseases
The pests and diseases that affect irises depend on theiIris species. However, among the more common problems faced by the plant are fungal and viral diseases that cause rhizome rot or infestation of aphids, Iris borers or weevils, verbena bud moth, thripes, and slugs and snails. Also, scale insects feed on irises and can harm the plant if left unattended.