Gardens & Conservatory

Plants & Collections

Japanese water iris adds ‘wow factor’ to water gardens

By Tom Brinda and Lynn Kirk, Lewis Ginter Botanical Garden
Published May 2008 in the Richmond Times-Dispatch

Want to make your water garden more striking? Need to dress it up with summer color? If so, the Japanese water iris may be your answer. Peggy Singlemann, director of horticulture at Maymont, has a passion for this moisture-loving plant, though its cultivars may not be readily recognized by local gardeners.

“When Virginians hear the word ‘iris,’ most immediately think of the tall bearded iris,” Singlemann said. “The bearded iris is a lovely, old-fashioned plant with upright, oval blooms, but the Japanese iris is unique. Its flat [horizontal] blooms can be as broad as a [dinner] plate,” measuring as much as 8 to 12 inches in diameter.

The Japanese water iris’s exotic beauty stems from its blooms’ breathtaking size, as well as their array of colors: plums and blues ranging to pale pinks and soft whites. The blossoms’ surfaces also present artistically beautiful texturing that resembles marbled velvets, speckled mattes and quilt-like satins.

“When massed together, these irises are stunning! They make quite a statement and give a whole different look to the garden – a real ‘pow’ factor,” Singlemann said.

“Japanese water irises bloom in June and July, after the bearded irises are done, so they also add a whole other blooming season to the summer garden.”

Historical roots
The origin and significance of the word “iris” vary among different cultures. In Greek mythology Iris was the goddess of the rainbow, so when used as a plant name, iris referenced the flower’s palette of colors. Ancient Egyptians used representations of the iris to symbolize immortality.

The Japanese and eastern Asian cultures, however, are most often associated with the water iris. There its beauty and mystery have been ceremoniously revered for more than 500 years. Growing naturally along waterways and salt marshes, the irises also served a useful purpose for farmers. Their annual blooming marked the beginning of the rainy season and the proper time for transplanting of rice crops.

Through the centuries, the Japanese cultivated and hybridized the iris with passion and pride. In 1869, the first Japanese water iris was transported to America, where it became a short-lived gardening sensation. Unfortunately, lack of understanding about the water iris’ specific needs hindered its overall growing success along the east coast. Interest waned until recent years, when homeowners installed backyard ponds, container water gardens, bogs and water features – all potentially ideal habitats for this plant.

Five basics
“Under the right conditions, Japanese irises are not fussy,” Singlemann said. “They’re basically happy if their needs are met,” including:
• Acidic soil, around pH 6.0
• Abundant water during spring and summer
• Rich mix of heavy loam to retain nutrition and moisture
• Heavy fertilizer, preferably manure
• Full sun or at least half-day sun

“In the past, it’s been a challenge to grow Japanese water irises here in Richmond because of the moisture factor” and tendency for drought-like conditions, Singlemann said. “But the addition of garden ponds and pools has made it easier. Japanese water irises are beautiful plants that everyone should be able to enjoy.”

Tips for planting & care
The Japanese water iris’s horizontal blooms are quite interesting when viewed from above, so consider locating your bog or water garden below a balcony or upstairs sitting area.

Plant your garden with early-blooming tall bearded iris and late-blooming Japanese water iris to extend your summer garden’s flowering season.

Avoid areas with newly poured concrete and crushed limestone, as they release lime that can prove fatal to the acid-loving iris.

If you wish to divide iris, do so every three to four years after the blooming season.