Dietes grandiflora

Large wild iris, fairy iris


Dietes grandiflora is a hardy species. It grows up to 1,5 m tall and makes an excellent garden plant for both small and large gardens, including coastal gardens.
Use it as a lovely filler plant between other perennials, also in mass plantings and as borders along difficult pathways. The delicate flowers appear in summer, in groups, with intervals of a few days to about two weeks, usually just before or after rain. Contrary to the short-lived flowers of D. bicolor, each flower lasts three days. The flowers attract plenty of insects, including bees and beetles, which in turn serve as food for insectivorous birds.

The genus Dietes comprises six species, Dietes bicolor, D. butcheriana, D. flavida, D. grandiflora, D. iridioides and D. robinsoniana. The first five are endemic to southern Africa, while D. robinsoniana comes from Lord Howe Island in the Tasman Sea (the sea that separates New Zealand and Australia). The local species grow mainly in the eastern summer rainfall regions of South Africa and Swaziland. Our focus is on D. bicolor (yellow wild iris) and D. grandiflora (large wild iris) because they are so readily available. Dietes are clump-forming plants characterised by evergreen fans of pointed leaves and a series of yellow or white iris-like flowers borne in spring or winter. They are easygoing, long-lived plants that seldom fall victim to serious pests or diseases.
When do they bloom?
The pretty flowers appear from October to January.
Most suitable climate
Although they are quite tough, extreme frost will damage the plants. They flourish in moderate climates with either winter or summer rain.
What they need
Location: full sun or light shade. In fact, they really don’t mind growing in shade in the morning and sun in the afternoon, or vice versa. They are at their best when planted en masse in the shade of deciduous or evergreen trees. You can also plant them along the narrow pathways between buildings, with varying light conditions during the course of the day.
Soil: they will grow in any soil type, from sandy to heavy clay to swampy spots near ponds or streams. Slightly acidic, well composted soil is ideal.
Water: the natural habitat of these plants is near water and they thrive with wet feet. However, they can also spend long periods of time without water – this is especially so for D. grandiflora. All dietes look their best if they are watered regularly during summer.
Get more value
Dietes species are easily divided; this should be done in early spring before the plants become too active. Once dug up, the individual fans of leaves provide a good indicator as to where to split each plant into new sets of leaves and rhizomes. Prolific amounts of seed are produced in oblong capsules, but the outer shell of the capsule is so hard that it can take years for it to break down and allow the seeds inside to germinate. For the determined gardener who wants to propagate dietes from seed, it is best to sow them in spring.
In a nutshell
* Suitable for mass plantings.
* Suitable for varying shade and sun patterns.
* Suitable for poorly drained soil.
* Easy to cultivate.
The Gardener