Dietes: Butterfly or African Iris

Dr. Douglas F. Welsh, Professor & Extension Horticulturist
Texas AgriLife Extension Service
Dietes bicolor
Dietes bicolor
Morea grandiflora
Morea grandiflora

Butterfly, or African iris are composed of several species of the genus Dietes, and have been used extensively in zones 8b and upwards for landscaping and water garden accents in recent years. Their slowly increasing clumps of narrow, sword-like foliage usually remain green through the winter unless burnt by temperatures below 25°F. Dietes have the ability to grow as tall as 4 feet under optimal conditions in moist soil or in water, and are usually about 3 feet in height in the flower bed.

Confusion over correct naming of these African plants occurred when the large plant group known as Moraea was split and renamed: those with evergreen rhizomes were now Dietes, and those having corms were left in the Mora ea group.

Dietes resemble their iris relatives in having upright, spiky leaves and flower stalks bearing a succession of blooms usually lasting only one day over a long period of time. They will adjust to full sun or part shade and are not fussy as to soil type. African Iris is usually hardy to 15 - 20°F. Each flower lasts about two days. Large seedpods ultimately form that are reminiscent of those of Louisiana iris.

D. vegeta makes large, grassy clumps with many 3 inch pale yellow flowers with colored markings of yellow and violet. They may be considered a little less maintenance-free than bicolor, because when the individual leaves die, they must be clipped off in order to maintain neatness, rather than pulled.

Dietes bicolor has fewer, larger, more tidy leaves and more rounded white flowers with a violet/brown spot. The cultivars known as 'Orange Drops' and 'Lemon Drops' are Dietes hybrids.

Moraea grandiflora is a choice plant for a sheltered spot in the Texas garden. The flowers are even larger than those of the better-known Dietes. There is also a variegated form.

When planted in shadier areas, D. vegeta makes a good substitute for the spiky look of a true grass. The Dietes will not bloom as frequently in shade as it would in full sunshine.

Place newly planted African Iris 2 to 3 feet apart, and fertilize about twice a year after establishment. After this, they will be tolerant of drier conditions. Use them in easy-care plantings with rosemary, False Red Yucca (Hesperaloe), pink Verbena tenuisecta, Hamelia (firebush), autumn sage (Salvia greggii,) or as a tall groundcover. Leave the long bloom spikes alone; they will continue to furnish flowers for a long time.

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