Description of Iris versicolor (Blue Flag Iris)

Iris versicolor is a hardy perennial plant native to North America. Many gardeners know it as the Blue Flag Iris or sometimes the Poison Flag. This iris brings a soft blue-purple colour to damp spots in the garden from late spring into early summer.

Appearance and Growth Habit

This iris typically reaches a height of 60 to 90 centimetres. It forms dense clumps of long, narrow leaves. These leaves are a deep green colour and have a sword-like shape. They create a strong upright structure in the garden.

The flowers appear on sturdy stalks. Each bloom has three petals that stand upright and three that curve downwards. The colour is usually a blend of blue, violet, and purple. You often see delicate veining and a splash of yellow or white on the lower petals. This combination attracts bees and butterflies when it flowers between May and June.

Perfect Growing Conditions

Iris versicolor excels in wet conditions. It is the ideal choice for the edges of a pond, a bog garden, or even planted in shallow water. It can handle water depths up to about 30 centimetres. The plant grows best in a sunny spot but will also manage in partial shade.

It is very hardy and copes well with British winters. The plant dies back in autumn and then regrows from its roots each spring. It needs soil that stays moist or even waterlogged to thrive.

Planting and Ongoing Care

You can propagate this iris by dividing its root system. The best time for this is in late summer or early spring. Dividing the clumps every few years keeps the plant vigorous and promotes better flowering.

Once established, it needs very little attention. You may want to remove the old flower stems after blooming. If the clump becomes too large, you can dig it up and split it to create new plants. This also prevents it from spreading too far.

Garden Uses and Benefits

Use Iris versicolor to add colour and vertical interest to water features. It works well planted in groups or as a single specimen. The flowers provide a lovely contrast against the green leaves and water.

This plant also offers ecological value. Its roots help to bind the soil at the water's edge, which reduces erosion. The plant can also help to improve water quality by absorbing excess nutrients. By offering nectar to pollinators, it supports local biodiversity.

A Note on Its Name

While its alternative name, Poison Flag, sounds alarming, the plant poses little risk with normal handling. As with many garden plants, it is wise to prevent pets or small children from chewing on it.

Iris versicolor is a practical and beautiful choice for any damp or watery garden area. Its easy-going nature and beautiful blooms make it a reliable perennial.