Iris ensata Geisha-Hiskiki - Japanese Water Iris

Iris ensata 'Geisha-Hiskiki' displays in summer large, very round and open flowers, with a deep purple-blue colour, animated by a superb yellow signal extended by a long white splash at the base of each sepal. This is a rhizomatous plant that thrives in moist to wet non-limestone soil and works wonders on the banks of water points, but also in lands that remain fresh in summer. Excellent cut flowers, especially used in ikebana, Iris ensata were once intensely cultivated in Japan for this purpose, especially around Edo (the ancestor of Tokyo).

Iris ensata (synonym kaempferi), known as hanashōbu in Japanese, better known as Japanese water iris, have nothing in common with our classic garden irises, except for their belonging to the iris family. The original Iris ensata is a fibrous rhizome plant native to Asia, specifically the wetlands of Japan, the Himalayas, and Siberia. These irises, known to be difficult to cultivate, love acidic and peaty soils (they do not tolerate excessive limestone), are water-hungry during their growing and flowering period, but appreciate slightly less moist soils in winter: they can be found in nature growing above the water level, which often drops in winter and rises again in spring with the melting snow.

The 'Geisha-Hiskiki' cultivar forms an erect, rather compact clump, reaching a height of 80cm (32in) in flower with a spread of 50 to 60cm (20 to 24in). The plant slowly spreads on the ground through its rhizomes, becoming more beautiful year after year. The deciduous foliage, of medium green colour, consists of long and slender ribbon-like leaves, sheathing at the base, marked by a prominent central vein. The flowering takes place between May and August depending on the climate, for a good 3 weeks. Flower stems emerge from the leaf clumps. Each stem bears 2 to 3 very large flowers, 12-15cm (5-6in) in diameter. They are composed of 3 large rounded, undulate and flat sepals, topped with 3 smaller, also flat petals. The centre of the flower is occupied by 3 small erect petaloid styles, of lighter colour.

Often cultivated on the banks of ponds and basins, Iris ensata, like many marsh plants, can live with their "feet" in the water during summer, but their rhizomes do not tolerate being submerged during winter, especially if it is freezing. In our gardens, these Iris ensata will thrive in a well-drained loamy soil, but not drying out in summer. Plant them, for example, in a heavy soil forming a slight depression, at the bottom of a slope or on a bank where the soil becomes moist through capillarity. Combine Iris ensata 'Geisha-Hiskiki' with Anemone rivularis, Daylilies, Darmera peltata, Lobelia 'Queen Victoria', Astilbes, Physostegia virginiana, loosestrifes, and Ligularias.