Iris ensata Dinner Plate Blueberry Pie - Japanese Water Iris

Iris ensata 'Dinner Plate Blueberry Pie' is a spectacular Japanese water iris that produces huge flat, more or less double, velvety flowers, of a beautiful bluish-violet colour with purple highlights, animated by small yellow signals in the centre. It is a mid-season variety that usually flowers in July. In contrast to our garden irises, this rhizomatous perennial is comfortable in non-limestone and waterlogged soils in summer. Superb when planted in mass in wet areas and on the banks of water points, Iris ensata were once intensely cultivated in Japan, especially around Edo (the ancestor of Tokyo), for cut flowers. 

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 in the Iridaceae family. The original Iris ensata is a fibrous rhizome plant native to Asia, specifically from the wetlands of Japan, the Himalayas, and Siberia. These irises, known to be difficult to cultivate, like acidic and peaty soils (cannot tolerate excess limestone), are thirsty for water during their growth and flowering period, but appreciate slightly less damp soils in winter : in nature, they are found above the often low winter water level, which rises again in spring with the melting snow. 

The cultivar 'Dinner Plate Blueberry Pie' is a recent horticultural creation from the 'Dinner Plate' series, which brings together varieties with oversized and remarkably coloured flowers. This magnificent 'Blueberry Pie' variety forms an erect, rather upright clump composed of fine leaves. The plant will reach approximately 60cm (24in) in height when in bloom and 50cm (20in) in width. This iris slowly spreads on the ground through its rhizomes, beautifying year after year. The foliage, deciduous in winter, of a medium green colour, is composed of long, slender, sheathing leaves with a prominent central vein. The non-remontant flowering is in summer, more or less early depending on the climate. Flower stems emerge from the clumps of leaves. Each one carries 2 to 3 very large flat flowers with a diameter of 15cm (6in). Each flower is composed of 6 large, flat, horizontal sepals, very undulated, topped with 3 slightly smaller petals and 3 erect styles. The sepals are a dark bluish-violet, more purple towards the edge. In the centre of the flower, bright yellow signals illuminate the whole. 

Often cultivated on the banks of ponds and basins, Iris ensata, like many marsh plants, can live with their "feet" in water during summer, but their rhizomes do not tolerate being submerged during winter, especially if it is freezing. In our gardens, these Japanese irises will thrive in loamy soil, well lightened with compost, but not drying out in summer. For example, plant them in a heavy soil forming a slight depression, at the bottom of a slope, or on a bank that becomes moist through capillarity. Associate Iris ensata 'Dinner Plate Blueberry Pie' with Anemone rivularis, Darmera peltata, Lobelia 'Queen Victoria', Astilbes, Lysimachias and Ligularias for example.