How To Grow Dietes Evergreen Iris Plants

Image by SharonWills

By Darcy Larum, Landscape Designer

Sometimes called butterfly flag, peacock flower, African iris or fortnight lily because it seems to send out new blooms every two weeks, Dietes bicolor is most frequently known as evergreen iris. Native to South Africa, Dietes iris is hardy in zones 8-11 and has naturalized in Florida, Texas, Louisiana, Arizona, New Mexico and California. Continue reading to learn more about evergreen iris plants.

Evergreen Iris Plants

Dietes evergreen iris looks like a clump forming, flowering ornamental grass and is frequently used in the landscape as one. However, it is actually a member of the iris family. Its blooms, which appear sporadically from May through September and sometimes throughout winter in the hottest zones, look similar to bearded iris flowers in shape and size. Evergreen iris blooms, though, are generally yellow, cream or white in color and variegated with black, brown or orange.

These blooms attract many pollinators to the garden and are an excellent addition to butterfly gardens. They make excellent, dramatic accents for container gardens too.

The sword-like foliage grows from rhizomes and can reach up to 4 feet high and are about an inch thick. As the plant matures, this foliage begins to arch and weep, giving it the appearance of an ornamental grass. The foliage is truly evergreen, though it may brown in temperatures that are too cold.

How to Grow Dietes Evergreen Iris Plants

Evergreen iris plants grow well in a wide variety of soils – slightly acidic to slightly alkaline, clay, loam or sandy – but they cannot tolerate dry, chalky soil. They prefer rich, moist soil and can tolerate growing in shallow standing water. This makes them excellent plants for use around water features.

They are labeled as a full sun plant but prefer bright morning sun with some filtered afternoon sun.

Growing an evergreen iris requires very little work or maintenance, as they only need to be lightly fertilized with a general purpose fertilizer once or twice a year.

In consistent, ideal temperatures, evergreen iris can self-sow and may become a nuisance if not kept in check. Every 3-4 years it is a good idea to divide Dietes evergreen iris.

Deadhead spent flowers as needed to control seed formation and keep the plant re-blooming. Flower stalks should be cut back to the ground after its short-lived blooms have faded.

In northern, cooler climates, Dietes evergreen iris can be grown as an annual bulb like cannaor dahlia.

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