Iris setosa

Iris setosa is a small wild iris that is found in very cold regions of the world. Braving the salty and icy winds of the Arctic, this small rhizomatous plant grows in dunes and anchors itself in rocks along watercourses, adapting to many wet or even drier habitats. In late spring, it blooms along the coasts of Alaska, northeastern Asia, Newfoundland, and Siberia, producing a multitude of small lavender-blue flowers streaked with white-silver in the throat. Bright and fresh, they perfectly match the clear skies of these regions. This charming perennial deserves to be discovered and planted in our sunny rockeries and borders. It is very robust, and only fears overly chalky and/or heavy and dry soils in summer. The Royal Horticultural Society has awarded it for its ornamental qualities and performance in the garden.

Iris setosa belongs to the Iridaceae family that is sometimes included in the group of Siberian Irises, sibiricae in Latin. It is a species closely related to I. ensata (from Japan), I. sanguinea (from Siberia), and I. versicolor, for example. Its distribution range includes the Aleutian Islands (Alaska), the state of Maine in the USA, Canada, Russia, and northern Asia, from China to Japan. It can be found in bogs and marshes, meadows, along rivers and streams, on rocky lake shores, on beaches, and dunes. This species tolerates sea spray as well as sandy and gravelly soils. It needs cold winters to flower well.

It is a perennial herbaceous plant with a long creeping rhizome that does not root much, and its above-ground vegetation dies in winter. Over time, depending on growing conditions, it forms clumps 15 to 30cm (6 to 12in) tall (for the foliage), spreading indefinitely through its rhizomes. The foliage consists of fine linear sword-shaped leaves, measuring between 30 to 60cm (12 to 24in) long and 1 to 2.5cm (1in) wide. The leaves are green with a violet base. Flowering takes place in June-July, depending on the climate. Flower stems of varying heights, between 10 to 80cm (4 to 32in), emerge from the foliage. Each stem, bearing one to three branches, carries 3 to 4 flowers (each plant bearing 6 to 13 flowers). Each flower, 5 to 7cm (2 to 3in) in diameter, consists of 3 beautiful narrow sepals that widen at the edges, 3 tiny upright petals reduced to bristles (hence the species name setosa, which means 'hairy' in Latin), and 3 pistils resembling small fringed petals. The dominant colour is a very bright blue-mauve, streaked with white and violet-blue in the throat. After pollination by insects, the flowers give way to fruits that are capsules containing seeds.

Siberian iris are wonderful plants for landscaping water features. However, this one is much more adaptable and will also thrive in a not too arid rockery, or in sunny borders. It always needs light soil. For example, combine it with small spring bulbs (botanical daffodils, tulips, Iris reticulata, grape hyacinths, Siberian squills), purple ornamental garlics, and poppies with bright colours, especially Iceland poppies.