Dietes iridioides aka Wild Iris

Dietes iridioides belongs to the iris family, Iridaceae. It is an evergreen perennial: it lives for years and stays green. Its common name is African iris. It comes from eastern and southern Africa. Kew gives its native range as Ethiopia to South Africa. It grows in a subtropical climate. It spreads from rhizomes, which are stems that grow underground. Its leaves and blooms look like those of a beardless iris.

Garden plants reach 2–4 feet (0.61–1.22 metres) tall. They can spread to about 3 feet (0.91 metres). Thin, sword-shaped leaves grow from the base in fan-shaped clumps. The leaves stay green where winters allow. Flower stalks branch above the leaves and hold many buds. Each white bloom spans about 3 inches (0.08 metres). Yellow and blue marks add colour to the petals.

Each flower lasts just one day, but new buds soon open. Blooms come in waves, often about two weeks apart. This gives the plant its other name, fortnight lily. Missouri Botanical Garden lists May to September as its bloom season. Where frost stays away, blooms last from spring through autumn. Some flowers may open in winter too. Seed pods form once the flowers fade. Removing young pods can help the plant grow more flowers.

Grow African iris in moist soil that drains well. It suits soil with a fair level of nutrients. Give it sun or part shade. Full sun gives the best bloom. Some light shade after noon may help in warmer sites. Plants cope with some dry soil. Yet they grow best with a steady supply of moisture. They are winter hardy in USDA zones 9–11. In colder places, grow them as annuals or in pots. Bring pots inside before frost. Or lift the rhizomes before the first autumn frost. Store them in peat or vermiculite at about 45°F.

Where hardy, African iris suits mass plantings and gardens needing little care. Its long bloom season adds colour among the upright leaves. In colder places, pots can stay outside during frost-free months. Keep flower stalks once blooms fade; do not cut them off. Remove dead leaves. Grow new plants from seed or by dividing rhizomes. Pests and diseases seldom cause serious harm. Root rot and rust can occur. Scale insects and nematodes may cause trouble too. The supplied sources do not show whether any parts are safe to eat. They give no clear evidence on whether the plant is toxic.