Iris ensata Dinner Plate Tiramisu - Japanese Water Iris

Iris ensata 'Dinner Plate Tiramisu' is another variety of Japanese water iris from the "Dinner Plate" series that features enormous plate-sized flat flowers. Its flowers are single to double, finely edged, and lightly speckled with purple on a white background, enhanced by small lemon yellow spots. This variety blooms in June-July. Unlike our garden irises, this rhizomatous perennial is comfortable in non-calcareous and waterlogged soils in summer. They look stunning when planted en masse in wet areas and along the edges of water bodies. Iris ensata were once extensively cultivated in Japan, especially around Edo (the ancestor of Tokyo), for cut flowers. 

Iris ensata (synonym kaempferi), known as hanashōbu in Japanese,  are better known as Japanese water irises and are quite different from our classic garden irises, except for their belonging to the iridaceae family. The original Iris ensata is a fibrous rhizomatous plant native to Asia, specifically the wetlands of Japan, the Himalayas, and Siberia. These irises, known for being difficult to grow, prefer acidic and peaty soils (they do not tolerate excess limestone), they crave water during their growing and flowering period, but appreciate slightly drier soils in winter: in nature, they are found above the water level which often drops in winter and rises in spring with the melting of snow. 

The 'Dinner Plate Tiramisu' cultivar is a recent horticultural creation from the 'Dinner Plate' series, which brings together varieties with oversized and remarkably coloured flowers. This 'Tiramisu' variety forms an erect clump of vegetation, composed of slender leaves. The plant will reach approximately 60cm (24in) in height when in bloom, with a spread of 50cm (20in). This iris slowly spreads on the ground through its rhizomes, beautifying 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 non-remontant flowering takes place in summer, more or less early depending on the climate. Flower stalks emerge from the clumps of leaves. Each stalk bears 2 to 3 very large flat flowers, measuring 15cm (6in) in diameter. Each flower is composed of large flat and horizontal sepals, very undulate, topped by slightly smaller petals and 3 upright styles. 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 tolerate having 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 Japanese irises 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 'Tiramisu' with other "Dinner Plate" varieties, Anemone rivularis, Darmera peltata, Lobelia 'Queen Victoria', Astilbes, Lysimachias and Ligularias , for example.