Original article by Sharon Turner from Walter Sisulu National Botanical Garden
Dietes grandifloraDC Family: Iridaceae Common names: large wild iris, fairy iris (Eng.); groot wilde-iris (Afr); isiqungasehlati (Z)
This well-known indigenous iris is commonly grown in gardens and used in large landscapes throughout the country.
Dietes grandiflora is a perennial, evergreen plant which grows up to 1.5 m, forming large clumps. The plant grows from underground rhizomes. The long, rigid, sword-shaped leaves, held in a fan shape, are dark green and may reach up to 1 m long and 15-20 mm wide.
The attractive flowers, held on erect slender stems about 1 m in length, are large (about 100 mm across) and are white with yellow nectar guides on the outer tepals and violet central segments.
The flowers are borne in masses at certain periods - often after rain in summer. The individual flowers do not last more than a couple of days (so are of no use in a vase) however, the plant bears so many flowers during the peak period that the plant looks most striking.
This plant is occasionally called the "Fairy Iris" because the fragile white petals not only look like fairy wings, but also have a tendency to disappear mysteriously overnight!
The large wild iris fruit is a large capsule up to 45 mm which is held erect and splits open to release shiny, dark brown seeds.
Least Concern (LC), Dietes grandiflora is not threatened.
It grows naturally along the southern and eastern coastal areas of the Eastern Cape and southern Kwazulu-Natal where it may be found in full sun or partial shade at forest margins, or in the shelter of taller shrubs on exposed slopes facing the sea.
The name Dietes means 'having two relatives' and refers to the relationship between this genus and Moraea and Iris. Grandiflora means 'large flower'. There are 6species of Dietes - five of which occur in South Africa - and one on an island in the Tasman Sea (between New Zealand and Australia). Dietes were once called Moraea (a closely related group), but were separated because Dietes have a rhizome, whereas Moraea have a true corm.
The flowers attract lots of bees and other pollinators.
It has become a popular landscaping plant due to its reliability and hardiness and is often found in parking areas at shopping centres, schools etc. It can be effectively used in mass plantings but is also effective in mixed plantings or used as an accent plant alongside a pond or some steps.
This is a popular, easy-to-grow garden plant which will grow under most conditions. The plants are both frost and drought hardy and will grow in either sun or shade. However, for best results and most flowers, plant Dietes grandiflora in full sun or light shade in well composted, well-drained soil and water well in summer.
The large wild iris is easy to propagate from seed sown in spring or by dividing large clumps which spread by means of rhizomes. They multiply rapidly and are soon ready to be split again.