Iris is an ideal plant for Bay Area gardens. Easy to grow and maintain, irises offer a wide range of colors and forms, are drought tolerant and deer resistant, harmonize well in Mediterranean, Asian and woodland type gardens among others, and produce spectacular cut flowers.
Iris is a large genus, comprising over 250 species of showy flowering plants. Taking its name from the Greek work for rainbow, irises span almost the full range of flower colors, from white to almost black and everything in between.
Irises in nature are widely distributed in temperate zones worldwide, in diverse habitats ranging from cold mountain areas to grassy slopes and meadowlands in Europe, Asia, Africa and North America. They are technically perennial herbs, growing from creeping rhizomes or bulbs.
Iris cultivation has been practiced for millennia. In ancient Greece, purple irises were planted over the graves of women to summon the Goddess to guide the dead in their journey. Ancient Egyptian kings were captivated by the iris’s exotic nature, and drawings have been found of the flower in a number of Egyptian palaces. Joan of Arc carried a white banner that illustrated the flower when she led French troops to victory over the English, and the iris, in the stylized form of the Fleur-de-lis, eventually became the recognized national symbol of France. Nineteenth century Italy named the iris as the symbol for Florence, and began drying the rhizome from which they made perfume. Even today orris root, which is made from the iris, is used as the scent in potpourris.
There are several species of iris native to California and the western United States. In addition, many irises that are not native to our area grow beautifully in Bay Area gardens. Here are a few of my favorites:
Native to California and Oregon, Douglas Iris is lower growing than most irises, reaching only about a foot in height. Flower colors run from purple, blue, chocolate mauve, and lavender to cream, with fine contrasting or yellow tracery. Plants form spreading clumps, with dark green leaves to 1 in. wide and 1 to 9 flowers per branched stem.
Eleven species native to Pacific Coast states constitute a homogeneous group within the genus Iris, from which breeders have developed hybrids in a broad range of colors and patterns; flowers may be white, blue shades, pink, copper, brown, maroon, violet—many with elaborate veining or patterning. Foliage is narrow; clumps are like coarse grass. Slender flower stems reach 8 to 24 in., depending on variety.
Best conditions are sun to light shade, well-drained soil, moderate to scant water in summer. In clay soil, grow in raised beds in organically amended soil. Plant from containers any time, though spring and fall are best, Timing is critical in digging, dividing, and replanting. Best moment is when new roots are starting to form (scrape away soil at plant base to check); this ranges from early fall in colder regions to midwinter in mild-winter areas.
Among the choicest perennials for borders, massing, and cutting. Easy to grow, with mid-spring flowers on branching stems 2 1/2 to 4 ft. high. All colors but pure red and green are available; patterns of two colors or more and blends produce an infinite variety. Countless named selections are available.
Yellow Flag Iris (Iris pseudacorus) bears 3-4 inch bright yellow flowers on branched stems in mid-summer. This evergreen iris likes moisture, and can tolerate standing water; it will naturalize where there is adequate moisture.
Japanese Iris (Iris ensata) is native to Japan, and features broad, flat blossoms that are 4 to 8 inches across in shades of purple, violet, pink, rose, red and white, often veined or edged in contrasting shades. These deciduous plants have graceful, narrow, upright leaves with distinct raised midribs. They like moisture, and tolerate standing water.