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Mendocino Coast Botanical Gardens, 47 acres of botanical bliss fronting the Pacific Ocean

Japanese Iris

Botanical Name: Iris ensata Common Name: Japanese iris Family: Iridaceae 

Description: The flowers on the Japanese Iris are large, lovely and in sizes of 4 inches to 12 inches across. The single types consist of 3 wide falls and small standards, and appear triangular in shape. The doubles have a circular shape. The colors are variations of purple, red and white.

Iris ensata is the original parent that was used to develop the large flowered forms. The leaves are long, slender and ribbed. The plant grows to about 42 inches, with flower buds rising above. The color range of the tetraploid cultivars, available since 1979, of white, blue, mauve, purple and pink seem few. The huge variety of patterns make up for the limited color range. They have a yellow signal on the falls and may be veined with fine dark lines, or covered with small darker dots and short broken lines. They might be brushed with minute dots, or edged around the falls and petals. The great range of shades available in each color makes for stunning effects in mass plantings.By choosing a selection of early blooming to late blooming varieties, these irises will be in bloom for about six weeks.

Cultivation: The derivations need much moisture while growing, with rich, well drained soil. This iris cannot take water-logging in winter or dormant phase. Lime, such as found in chicken manure and mushroom compost, is damaging to these plants. Japanese iris performs best when it is lifted, dug out of the soil, every 3 to 4 years and trimmed of dead and unhealthy rhizomes and roots. Then it can be divided and replanted in a bed that has lots of compost added to it. This iris thrives in coastal climates.

Propagation: Rhizomes can be planted in fall or spring, 2 inches deep, or up to 3 in a 12 inch pot, in sun or partial shade depending on locality. If the plant is genetically equipped, it can bloom several times a year.

Submitted by Master Gardener Harriet Gere, 2007.