Iris versicolor (blue flag) — Clump forming

Overview

Iris versicolor is a clump forming aquatic in the genus Iris, part of the Iridaceae family, with deciduous foliage. It typically grows around 0.5-1 metres tall and 0.1-0.5 metres wide, reaching full size in around 2-5 years. Iris versicolor grows best in full sun, and tolerates most soils and acid and neutral pH. Its UK hardiness is rated H6. It is low maintenance. Suggested uses include cottage and informal garden, coastal and flower borders and beds. It is native to Labrador, Newfoundland, Manitoba, New Brunswick, Nova Scotia, Nunavut, Ontario and Prince Edward Island.

About

Iris versicolor or Iris versicolour is also commonly known as the blue flag, harlequin blueflag, larger blue flag, northern blue flag, and poison flag, plus other variations of these names, and in Great Britain and Ireland as purple iris. It is a species of Iris native to North America, in Eastern Canada and the Eastern United States. It is common in sedge meadows, marshes, and along streambanks and shores. It is one of the three Iris species in the Iris flower data set outlined by Ronald Fisher in his 1936 paper "The use of multiple measurements in taxonomic problems" as an example of linear discriminant analysis. It grows to around 0.5-1 metres tall and 0.1-0.5 metres wide, carrying deciduous foliage. Grow it in full sun and most soil types. It tolerates acid and neutral soils, poorly-drained conditions and south-facing and west-facing aspects.

Wikipedia contributors, CC BY-SA 4.0 — Iris versicolor

About the genus

Iris takes its name from the Greek goddess of the rainbow, and for once the naming feels entirely earned. I can't think of another genus that covers so much ground — inky purples, burnt apricots, clean whites, blues that seem lit from inside — or so many situations. There are bearded irises that want their rhizomes baked in full sun, Siberian types happy in ordinary border soil, and species that will sit contentedly at the edge of a pond. What they share is the flower: three petals standing up, three falling away, built with a kind of architectural confidence most plants never attempt. Even out of bloom the foliage earns its place — those upright fans of blue-green leaves hold a border together for months. I grow them for the fortnight in May and June when nothing else in the garden can compete, and I've made my peace with that. Some plants are for the long haul. An iris is an event.

Written by Henry

Growing conditions

Best soil and position for Iris

Sunlight: Full sun
Soil type: Clay, Loam, Sand
Soil pH: Acid, Neutral
Soil moisture: Poorly-drained
Aspect: South-facing, West-facing
Exposure: Exposed, Sheltered
UK hardiness: H6

Plant details

Iris versicolor size, habit and characteristics

Plant type: Aquatic, Bogs, Herbaceous Perennial
Habit: Clump forming
Foliage: Deciduous
Height: 0.5-1 metres
Spread: 0.1-0.5 metres
Time to full height: 2-5 years
Suggested uses: Cottage and informal garden, Coastal, Flower borders and beds
Native to: Labrador, Newfoundland, Manitoba, New Brunswick, Nova Scotia, Nunavut, Ontario, Prince Edward Island

Care notes

Pruning and caring for Iris versicolor

Propagation: Division, Seed
Pest resistance: Slugs, Snails, Thrips
Disease resistance: Aphid-borne viruses, Bacterial soft rot, Grey moulds

Frequently asked questions

Where is the best place to plant Iris versicolor?

Iris versicolor prefers full sun. It suits exposed and sheltered positions.

What soil does Iris versicolor need?

Iris versicolor is adaptable and grows happily in most soil types, including clay, loam and sand. It prefers acid and neutral soil. Aim for soil that stays poorly-drained.