Iris ensata Dainagon - Japanese Water Iris

The Iris ensata Dainagon concentrates in its large open, flat, undulating flower all the splendour and refinement of Japanese floral art.  This opulent variety of Japanese water iris unfolds in summer large delicate flowers of a fairly deep mauve-violet, randomly splashed and veined with white, discreetly enhanced by a small yellow signal nestled in the corolla's heart. It is a rhizomatous plant that prefers non-limestone damp to moist soil and will work wonders on the banks of water, but also in areas that remain moist in summer. Excellent cut flowers, especially used in ikebana, Iris ensata were once intensively cultivated in Japan for this purpose, especially around Edo (the ancestor of Tokyo).

Iris ensata (synonym kaempferi), hanashōbu in Japanese, better known as Japanese water iris, have nothing in common with our classic garden irises, except for their membership of the iridaceae family. The original Iris ensata is a fibrous rhizome plant native to Asia, more precisely to 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 excess limestone), are water-loving during their growth and flowering period, but appreciate slightly less-moist soil in winter: they are found in nature growing above the water level, which often decreases in winter and then rises in spring with the melting of snow.

The 'Dainagon' cultivar forms an erect, rather upright clump, reaching up to 80cm (32in) in height when in flower, with a span 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 a medium green, consists of long and slender ribbon-like leaves, sheathing at the base, marked by a prominent central vein. Flowering takes place between May and August depending on the climate, lasting for 3 good weeks. Flower stems emerge from the leaf clumps. Each stem bears 2 to 3 very large flowers measuring 12-15cm (5-6in) in diameter. They are composed of 3 large rounded and flattened sepals veined with white on a dark mauve background, topped with 3 smaller and more upright flattened petals, and 3 wide and upright styles.

Often grown on the banks of ponds and basins, Iris ensata, like many marsh plants, can tolerate having their "feet" in water during summer, but their rhizomes do not tolerate being submerged during winter, especially if it is freezing. In gardens, these Iris ensata will thrive in loamy soil enriched with compost, but not drying out in summer. For example, plant them in heavy soil forming a slight depression, at the bottom of a slope, or on a bank where the soil becomes moist through capillary action. Combine Iris ensata Dainagon with Anemone rivularis, Hemerocallis, Darmera peltata, Lobelia Queen Victoria, astilbes, Physostegia virginiana, lysimachias, and ligularias.