Iris ensata Mme Bigot - Japanese Water Iris

Iris ensata 'Mme Bigot' is a very rare variety of Japanese water iris that is highly appreciated for its large round flowers delicately veined with blue on a background of white washed with a soft blue. When fully open, they display a bright yellow signal at the base of each petal. Plant this rhizomatous perennial in moist soil, for example on the edges of a pond or in good loamy soil that never dries out in summer. It can be grown in full sun or light shade, in acidic to neutral soil. Stunning when planted en masse near water features, Iris ensata also provide beautiful flowers for bouquets.  

Iris ensata (synonym kaempferi), known as hanashōbu in Japanese,  are quite different from our classic garden irises, except for belonging to 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 to be difficult to grow, prefer acidic and peaty soils (they cannot tolerate excessive limestone), are thirsty for water during their growing and flowering season, but appreciate slightly less humid soil in winter: they are found in nature growing above the water level that often drops in winter, then rises in spring with the melting of snow. 

The cultivar 'Mme Bigot' forms an erect, bushy clump, reaching 90cm (35in) in height when in flower (60cm (24in) for the foliage) with a spread of 40 to 50cm (16 to 20in). The plant slowly spreads on the ground through its rhizomes, becoming more beautiful year after year. The deciduous foliage, of medium green, consists of long and slender ribbon-like leaves, sheathing at the base, marked by a prominent central vein. The flowering takes place between June and August, depending on the climate, in the middle of the Iris ensata season, lasting for 3 good weeks. Floral stems emerge from the tufts of leaves. Each stem bears 2 to 3 large flowers, 12-15cm (5-6in) in diameter. They are composed of 3 large rounded and flattened sepals, topped with 3 equally wide and flattened petals, in the same white-blue veined with soft blue. The centre of the flower is occupied by 3 small erect petaloid styles, infused with blue and white. 

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 Iris ensata will thrive in a loamy soil enriched with compost, but not drying out in summer. Plant them, for example, 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 'Mme Bigot' with Anemone rivularis, Daylilies, Darmera peltata, Lobelia 'Queen Victoria', Astilbes, Physostegia virginiana, loosestrifes and Ligularias. 

Excellent cut flowers, especially for ikebana arrangements, Iris ensata were once intensively cultivated in Japan for this purpose, particularly around Edo (the ancestor of Tokyo).