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Easy Irises — an introduction

: Iris is an easily propagated perennial that comes in a rainbow of colours.

: Iris is an easily propagated perennial that comes in a rainbow of colours.

Irises are among the easiest of perennials to grow, and they give an abundance of beauty with minimum care. From the stately bearded iris down to tiny plants that grow from bulbs, the iris provides a delicate beauty throughout the year.

Irises are ancient garden plants, which were cultivated in parts of Asia long before the Christian Era. There are more than 200 species, all indigenous to the northern hemisphere. Irises come in a rainbow of colors – which is why they were named Iris, for the Greek goddess of rainbows. There are bearded iris, beardless iris, wild iris and hybrid iris. Over 200 species grow wild. There are thousands of hybrid varieties.

Almost all iris have at least 2 things in common – sword shaped leaves and a distinctive flower structure consisting of 3 upright petals called “standards” and 3 outer petals called “falls” which hang down from the base of the blossom.

There are two types of iris — those that grow from rhizomes (thick, spreading underground stems) and those that grow from bulbs.

The most popular of the rhizomatous types are the bearded irises, which have fleshy hairs like a small beard on the outer petals. They are also known as flag irises or German irises, and are classified by height ‑ tall (70 cm and over), intermediate (40 ‑ 70 cm), semi­-dwarf, and dwarf (under 25 cm). All have broad leaves, and flower colours include white, pink, blue, gold, red, and many combinations of these.

Tall bearded irises flower in early summer, intermediates flower in late spring, and the dwarf varieties flower in spring.

Apart from the bearded types, there are other equally beautiful irises. They are divided into a number of groups, containing both species and hybrids. Many of the hybrids make better garden plants than the species.

Iris kaempferi (Japanese water iris) is the most popular of the Laevigata (Water iris) group. It produces flat-topped flowers in shades of white, pink, blue and purple, during early and mid‑ summer.

Water irises need plenty of moisture, particularly in summer, and you can even plant them in 5 ‑ 10cm of water, either in pots or directly into the bed of the pond. In very hot, dry areas the plants need a slightly shaded position. In milder climates they will thrive in full sun.

Irises of the Louisiana group, such as Iris fulva and its many hybrids, are suitable for most areas of the country, provided they receive plenty of moisture during the summer. Their flowers are borne on 1m high stems in early summer, and are similar to those of the Dutch iris, but the falls (petals) are much wider. The main colours are lavender, pink, and purple.

Pacific Coast irises belong to the Californicae group and there are a number of species, such as Iris douglasiana and Iris innominata, as well as many hybrids. These irises do not grow well in very cold areas, but thrive in the milder regions, particularly in the Western Cape. Pacific Coast irises are small plants with slim, evergreen leaves. The flowers appear from spring to summer and are produced in shades of yellow, orange, and blue, as well as white. They are borne on wiry stems that range in height from 20 ‑ 45cm. These irises flourish in full sun or semi-shade in lime‑free soil.

The Spuria irises are particularly easy to grow. There are a number of species, the most common of which are Iris ochroleuca, with white and yellow flowers, Iris monnieri, with fragrant yellow flowers, and Iris aurea, with golden yellow flowers. There are also many colour variations of these. Spuria irises are tall plants, growing up to 1m high. They need plenty of water during the growing period and die down in frost‑affected areas.

The Siberica group of irises (Siberian irises) are also tall, growing up to 1,25 m high. Their leaves are narrow and grass‑like, and the flowers appear in late spring on tall, slender stems, which are ideal for cutting. The usual shades are purple and blue. Siberian irises prefer a position that gets full sun, and they need plenty of moisture — in very hot, dry areas, they should receive semi‑shade during the summer.

The crested irises, which include Iris japonica, Iris wattii, and Iris tectorum, have orchid‑like flowers with attractive crests instead of beards on the falls looking rather like cockscombs. They love shade and moisture, and flower in the spring.

Bulbous irises are cultivated in the same way as daffodils and freesias. The most important of these are members of the Xiphium group, and the hybrid Dutch irises (developed from a number of different species) are the most commonly grown type. These hybrids have large flowers, up to 10 cm across, and the usual shades are blue, purple, yellow, and white.

Dutch irises are planted in autumn and flower in the spring, blending well with all the other spring‑flowering bulbs. In areas where the weather may be hot and dry during spring, such as the Northwest / Gauteng / Mpumalanga highveld, they should be planted in semi‑shade, although they can be grown in full sun. The bulbs should be lifted and stored in the same way as daffodils.

English irises (Iris xiphoides) are similar to Dutch irises but flower later. However, they are not easy to grow and are not readily available.

Bulbous irises in the Reticulata group are quite distinctive. They grow to a height of 10 ‑ 20cm, and have square-section foliage. They flower in late winter and early spring (some of the blooms are pleasantly scented).


The sword-like leaves and upright growth of irises makes a nice contrast to other plants in the garden all season long. Together with roses and peonies, bearded irises are the stars of the early summer flower garden.

Other excellent perennial companions include Rudbeckia ‘Goldsturm’, purple coneflowers (Echinacea), Sedum ‘Autumn Joy’, lilies, Russian sage, and ornamental grasses such as blue oat grass (Helictotrichon sempervirens) and feather reed grass (Calmagrostis x acutiflora ‘Karl Foerster’).

Dwarf bearded irises make ideal rockery plants, teaming nicely with thyme, hen-and-chicken (Sempervivum) and pinks (Dianthus).

This introduction is the first in a series of feature posts on Irises. Future features will deal with ‘Growing and caring for Irises’ and ‘Propagating Irises’. Visit soon for new posts.