Dietes and Butterfly Iris

How to choose a dietes

The Fairy Iris, Dietes grandiflora, is the largest: a clump of dark green, sword shaped leaves about a metre tall, with big white flowers marked in yellow and mauve. The Butterfly Iris, Dietes iridioides, is similar in flower but smaller in every part, generally under 60 centimetres, which suits path edges and smaller beds. Butterfly Iris Tiny Dancer is a compact selection of the same species, and the Fortnight Lily in this range is White Tiger, grown for its striped, variegated leaves.

The Peacock Flower, Dietes bicolor, looks different again. It has narrower, paler, arching leaves and soft lemon yellow flowers with a dark blotch at the base of three petals. It makes a graceful clump about a metre tall. The range also includes named landscape selections of grandiflora and bicolor bred for mass planting.

Where dietes grows

Almost anywhere in Australia outside the wet tropics and the coldest alpine districts. Dietes take full sun or part shade, coastal exposure, most soils including clay and sand, and moderate frost once established. They flower most freely in sun. In heavy shade they stay green and healthy but bloom less.

They are used along driveways and fences, around pools, under trees and on banks, and they pair well with other strappy plants. See our grasses and strappy leaf plants, lomandra and drought tolerant plants for companions.

Planting and spacing

Plant at the same depth as the pot, water in and mulch. For a continuous border or mass planting, space the taller kinds 60 to 80 centimetres apart and the smaller butterfly iris forms 40 to 50 centimetres apart. Clumps widen slowly by rhizomes and fill the gaps over a couple of seasons. They can be planted at any time of year in mild climates, with autumn and spring the easiest.

Care basics

Water regularly for the first few months. After that dietes need little: a deep soak in long dry spells keeps the flowers coming. Feed in spring with a slow release fertiliser.

Take care when tidying. On the fairy iris and butterfly iris the flower stems are long lived and bloom again in later flushes and following years, so do not cut them to the ground; remove only stems that have browned off. Do snap off the green seed pods as they form. This saves the plant's energy and stops self sown seedlings, which matters near bushland, where dietes should not be allowed to spread. Pull out dead leaves from the base, and lift and divide crowded clumps in autumn. Our fortnight lily care guide has more detail.

Common questions

Is dietes the same as butterfly iris?

Yes. Butterfly iris, fairy iris, wild iris and fortnight lily are common names for dietes, used loosely across the different species. Peacock flower usually means the yellow Dietes bicolor.

How long does each flower last?

Only a day or two, but they open in waves over many months, so a clump is rarely without flowers in the warm season.

How far apart do I plant dietes?

About 60 to 80 centimetres for the taller species and 40 to 50 centimetres for compact forms.

Can I cut dietes back hard?

An old, untidy clump can be cut down to about 15 centimetres in late winter and will regrow, though it may miss a season of flowers. Dividing the clump is often the better fix.