Iris ensata Darling - Japanese Water Iris

Iris ensata 'Darling' is an extremely graceful variety of Japanese water iris, which has won numerous awards. In summer, the plant stands at 90cm (35in) tall and produces very large flowers in a delightful soft lilac pink, delicately enhanced by a small bright yellow signal. Its flowers, with their gracefully drooping sepals, are sometimes referred to as double, due to the bunch of particularly developed petaloid styles that adorn the heart of the flower. Unlike our garden irises, this rhizomatous perennial is comfortable in non-calcareous and waterlogged soils in summer. These beautiful plants are superb when planted en masse in wet areas and on the banks of water points. Iris ensata were once intensively cultivated in Japan, especially around Edo (the ancestor of Tokyo), for cut flowers. 

Iris ensata (synonym kaempferi), known as hanashōbu in Japanese,  are more commonly referred to as Japanese water irises, and bear no resemblance to our classic garden irises, except for their belonging to the Iridaceae family. The original Iris ensata is a fibrous rhizome plant native to Asia, specifically to the wetlands of Japan, the Himalayas, and Siberia. These irises, known to be difficult to grow, thrive in acidic and peaty soils (cannot tolerate excessive limestone), and require plenty of water during their growing and flowering period, but appreciate slightly drier 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 'Darling' cultivar forms an upright, rather erect clump, reaching approximately 90cm (35in) in height when in flower (60cm (24in) for the foliage) and spreading 50 to 60cm (20 to 24in) wide. The plant slowly spreads on the ground through its rhizomes, becoming more beautiful year after year. The deciduous foliage is a medium green and consists of long, slender, sheathing leaves with a prominent central vein. The flowering takes place between May and August, depending on the climate, lasting for 3 good weeks. Flower stems emerge from the tufts of leaves, each carrying 2 to 3 large flowers measuring 15cm (6in) in diameter. They are composed of 3 large, pendulous sepals finely veined in dark pink on a lilac pink background, adorned with a bright yellow signal at the base, topped with 3 petaloid styles and 3 much smaller, erect petals. 

Often cultivated 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 our gardens, these Iris ensata will thrive in well-drained loamy soil enriched 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 where the soil becomes moist through capillarity. Combine Iris ensata 'Darling' with Anemone rivularis, daylilies, Darmera peltata, Lobelia 'Queen Victoria', Astilbes, Physostegia virginiana, loosestrifes, and Ligularias.