Iris ensata Caprician Butterfly - Japanese Water Iris

Iris ensata 'Caprician Butterfly' is a very beautiful variety of Japanese water iris with large bicoloured flowers: its wide white sepals, veined with a deep blue, open widely around a heart with a small golden yellow spot that welcomes smaller, darker petals, almost violet. In stark contrast to our garden irises, this rhizomatous perennial is comfortable in non-calcareous and waterlogged soils in summer. Superb when planted in masses in wet areas and on the banks of water bodies, 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 better known as Japanese water irises and 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 wet areas in Japan, the Himalayas, and Siberia. These irises, known for being difficult to grow, prefer acidic and peaty soils (cannot tolerate excess limestone), are thirsty for water during their growing and flowering period, but appreciate slightly less humid soils in winter: they are found in nature growing above the water level, which often drops in winter and rises again in spring with the melting of snow.

The 'Caprician Butterfly' cultivar forms an erect, rather compact clump, reaching approximately 70cm (28in) in height when in bloom and 40cm (16in) in width. 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, slender, sheathing leaves with a prominent central vein. Flowering takes place between May and August, depending on the climate, lasting for 3 good weeks. Flower stalks emerge from the clumps of leaves. Each stalk bears 2 to 3 large flowers, 12cm (5in) in diameter. They consist of 3 large, flat sepals veined with violet on a white background, topped with 3 smaller, more delicate petals.

Often cultivated on the banks of ponds and basins, Iris ensata, like many marsh plants, can live with their "feet" in water during the 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 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 is moistened by capillarity. Combine Iris ensata 'Caprician Butterfly' with Anemone rivularis, Darmera peltata, Lobelia 'Queen Victoria', Astilbes, Physostegia virginiana, Lysimachias, and Ligularias.