1305 Dietes bicolorCommon Names: African iris,yellow wild iris,butterfly flag,bicolor iris Family: Iridaceae (iris Family)
African iris is a clumping perennial that spreads on thickened rhizomes which creep just below or at the surface. The sword shaped leaves are all basal, and carried in two ranks, with the clump appearing fan shaped. Leaves are pale green, leathery, and about two feet (60 cm) long. Flowers are produced at the tops of branched scapes (stalks) 2-3 ft (60-90 cm) tall. They are a pale lemon yellow, and about 2-3 in (5-7 cm) across. The flowers are short lived, but produced in succession throughout the growing season and even intermittently in winter. Six tepals are actually modified petals and sepals. Each of the outer, larger, three tepals has a dark brown splotch near its base. The fruit is a many-seeded capsule that splits open at maturity.
African iris is similar to the closely related fortnight lily (Dietes iridioides, aka D. vegeta) but fortnight lily has wider leaves and white flowers with yellow (rather than brown) blotches on the three larger tepals. Hybrids between the two species include the cultivars ‘Lemon Drops’ which has cream colored flowers with lemon yellow markings, and ‘Orange Drops’ whose flowers have orange markings.
Dietes bicolor hails from South Africa where it grows in moist grasslands, marshes, and along streams.
Light: African iris is grown in full sun to part shade. Nearly full sun gives the best flowering, but a little afternoon shade is important in the hottest climates. Plants in full sun should get more frequent irrigation. Moisture: For best flowering, grow African iris in moist but well drained soil. It can tolerate dry times, but needs regular watering to be at its best. African iris can tolerate periods of flooding. Hardiness: USDA Zones 8 - 11 . Dietes bicolor is the hardiest of the six species in the genus. Where not hardy, the rhizomes can be dug up before the first frost and stored in a dry medium for the winter, or they can planted in containers and allowed to continue growing indoors for the winter. Propagation: Divide the rhizomes in summer. Fresh seed germinates readily in a warm, moist potting medium.
Where hardy, African irises usually are grown in masses. If they are in a good site, they will gradually spread to form large clumps. Use as an accent plant either in the ground or in a container alongside entranceways, stairs or paths. African irises also are useful in borders, where they provide a strong vertical aspect. Use them as edging along paths, and for naturalizing in low maintenance gardens. Plant a patch in front of leggy shrubs to conceal the bare trunks. African iris tolerates poor, dry soils as well as periodic flooding, and is therefore a great plant for rain gardens. (See our Ginnie’s rain garden articles) African iris blossoms last only one or two days, but the plants produce a succession of flowers from spring until fall, often peaking in two week intervals. Remove seed pods to encourage more flowering, and cut the entire flowering stalks to the ground when blooming is completed. (Note that the other species of Dietes have perennial flowering scapes that should NOT be cut back after flowering.)
Where not winter hardy, the rhizomes are lifted and brought inside in winter, or the plants are grown in containers.
There are six species of Dietes, with five of them restricted to South Africa, and one to Lord Howe Island, Australia. The Iridaceae family has some 1700 species in about 82 genera, with more than half occurring in South Africa!
Steve Christman 3/16/18