Star Gardener

By Abby Jane Brody

A clump of white iris in the garden insistently drew my attention during the last half of June. Something about it in my garden in New Jersey prompted me to bring a piece to East Hampton. For the last 10 years I haven't paid it any attention. I thought it was a Siberian iris and let it go at that.

But this year it refused to be ignored and insisted I come by for a look. Its three flat petals are wider than those of a Siberian iris and have an elegance and refinement that told me it is one of the Japanese iris, Iris ensata, that flower from mid-June to mid-July depending on the cultivar. The texture of the petals is thick enough to preserve its integrity even after a heavy rain.

The Japanese iris, while long identified with Japan, also grows in the wild in Manchuria, Northern China, Korea, and Siberia. They have been admired, sometimes passionately so, since at least the early 13th century, when they were described in a Japanese poem. It appears that only great wars and depressions have destroyed the work of breeders going back to the 17th century in Japan.

"The Japanese Iris" by Currier McEwen was sponsored by the Society of Japanese Irises. It traces their history, botany, and culture, as well as diseases, hybridizing, exhibition, and where to see and buy them. Dr. McEwen, who died recently in his 90s, retired as dean of medicine at New York University to South Harpswell, Me., where he bred both Siberian and Japanese irises. He was the first to introduce a tetraploid Japanese iris, a blessing or not depending upon your point of view.

The book is very readable and has color plates showing the most important forms. It is available at the library of the Horticultural Alliance of the Hamptons in Bridgehampton. Do borrow it and perhaps you will want a copy of your own.

Do not, do not confuse the Japanese iris, I. ensata, with Iris japonica, which is lovely, but not hardy in our climate.

Lovers of the Japanese iris agree it was brought to the highest point of its development by Matsudaira, who grew iris for 60 years beginning about 1800. He introduced more than 100 new varieties, some of which are thought to still be grown today. He wrote that both singles and doubles were so taken for granted that it would take something like a peony bloom to capture attention.

Years later he succeeded, writing, "For several decades I had been struggling to produce the flower of my dreams and finally, it seems, man's efforts and the efforts of the maker of the universe coincided, and the rare flower made its appearance."

The first time Japanese iris made a lasting impression on me was on a summer tour of the garden of Emily Cobb and Ann Stanwell in Springs. As I recollect, the iris were growing in the back of the garden in a low, damp spot. I'm sure I am not their only visitor inspired to try growing the iris.

Japanese iris are associated in our minds with water, and have a very strong connection with East Hampton. Mrs. Lorenzo G. Woodhouse created a water garden, the Fens, in 1901 from a marsh behind her house on Huntting Lane. It had masses of Japanese iris in various pastel colors as far as the eye could see.

Childe Hassam, who lived on Egypt Lane across from the garden, captured the iris best in his painting "The Water Garden" from early summer 1909. The iris were also photographed beautifully in a hand-colored glass lantern slide of a photograph taken in 1915. Both were in an exhibit held last summer at Guild Hall, "Hamptons Gardens: A 350-Year Legacy."

Back to today's gardens, a variegated leaf form of I. ensata works well placed next to a small pool. Each blossom of I. ensata lasts only three days and they look lovely reflected in water. The white and green vertically striped leaves make a more lasting contribution to the garden.

When you purchase I. ensata, it is important that the plant have good branching to compensate for the brief blooming period of individual flowers. Some cultivars send up successive bloom stalks for five weeks or more. Other varieties have a second bloom period after a rest period of one to three weeks.

If certain cultural requirements are met, Iris ensata will grow well on the East End. According to Dr. McEwen, I. ensata requires acid soil, which we certainly have. They need abundant water, although they are not water plants. (If they are grown in pots under water, they require special treatment and should not be allowed to stand in water or ice over winter.) Often they are grown along the banks of ponds.

They are heavy feeders and require abundant fertilizer. They grow better in heavy loam soil. Lighter, sandy soil should be amended with compost, well-rotted manure, or other organic matter. In spring when the leaves are about three inches tall, established plants should receive a side dressing of granular fertilizer; a second side dressing should be added following the end of bloom.

Well-rotted manure is a good mulch, suppressing weeds and conserving water. Dr. McEwen recommends adding the manure in autumn and leaving it as a spring mulch. He also suggests removing the seed pods before they mature and cutting back the foliage as close to the ground as possible after it browns. This reduces debris in which pests can live over the winter and avoids having to clean up messy dead leaves in spring.

In our area the iris should be in full sun; they require a minimum of a half-day of sun. The experts say their rhizomes can and ought to be planted deeper than those of other iris, and clumps usually need to be dug, trimmed of old rhizomes and roots, and replanted in rich soil every three or four years.

My clump of single white iris with yellow signals has broken nearly every cultural requirement for I. ensata except for the acid soil and sun. It is covered by a mulch of strawberry plants with cream-colored double flowers. It has received only an occasional topdressing of chopped oak leaves or compost, and the sandy soil is a main thoroughfare for moles and voles.

Those of us who gardened and learned plant names before 1985 first met this plant as Iris kaempferi, the name given it by von Siebold in 1886. It was later found that the same species had been already named Iris ensata in 1794 by Thunberg and with much gnashing of teeth that name was officially adopted.

As soon as I identified the flowers in my own garden, I became aware of them in other places, too. The weather this year has been good to so many flowering plants, including the Japanese iris. As I drove along Cedar Street in East Hampton last week a clump caught my eye and I came to a screeching halt. No one was home, but since they were planted by the street I took a photograph of a highly saturated red wine purple flower with six large overlapping falls, sharp yellow signals, and the appearance of velvet.

The trial beds at the wholesale Garden Treasure Nursery in Sagaponack have large swaths of about a half-dozen different varieties. One grouping is of I. ensata Pink Frost. It is an elegant double with six overlapping falls of light pink and purple veins with a central small yellow signal. Like most I. ensata the foliage is between 24 and 30 inches high.

I. ensata Azuma Kagami is a sort of novelty, but frequently grown plant. It is a double with six white falls with dark purple veins, yellow signals, and three broad purple styles. While many varieties of I. ensata would blend in well in a perennial garden, this showy form would be better as a specimen.

Google "Society for Japanese Irises," which has an excellent Web site, to learn more about these late-flowering elegant irises. There is a national network of display gardens and a listing of specialty nurseries, a number of which are in the Mid-Atlantic States and New England. Pay a visit to local garden centers to get started. I suspect that if you have enough sun and space, one Japanese iris could lead to another and another.