Going native with Louisiana iris

Louisiana irises are lagniappe - a Creole term for a little something extra - for your spring garden. In the perennial quest for succession of color, Louisianas offer a regal seasonal transition, blooming in tandem with, or just after, bearded irises and fading as daylilies begin their reign.

Elegant, beardless Louisiana irises bring height, color, and contrast to perennial beds and borders, water gardens, and containers. Despite their name, they thrive in settings beyond the Bayou State's borders - in fact, Louisiana irises are at home in most of the US, even into Canada, as long as their roots are well mulched and they have sufficient water, sunshine, and acidic soil.

Uniquely American, they're native to Louisiana and the southeastern United States, and occur naturally as far west as east Texas, and as far north as Arkansas and Missouri.

There are five species: Iris fulva, I. giganticaerulea, I. hexagona, and I. nelsonii. Flower forms vary from pendant to flat to flaring, and may be single or semidouble, and from 1 to 7 inches across. Edges may be smooth, lacy, or ruffled, with stalks 1 to 5 feet tall.

A life of irises

In Little Elm, Texas, the delicate-looking flowers appear in late April, at times resembling swarms of butterflies over the backyard pond and dry-land beds at Marie Caillet's lakeside cottage. Among her perennial favorites are Cajun Sunrise, Little Caillet, Aunt Shirley, Just Helene, and Delta Star. Newer types and experimental hybrids are in special beds so they can be monitored for their potential as garden plants.

Ms. Caillet and fellow iris experts rank them for sturdiness, type of bloom and color, number of blooms per stalk, and overall appearance.

An octogenarian, Caillet remains more active and influential in the iris world than many people half her age. She tirelessly hosts spring tours of her garden, presents lectures, writes articles, corresponds with horticulturists, and wades into her pond each September to divide iris clumps and discard ones that didn't make the final cut.

As the nation's longest-tenured promoter of these irises, she has been a leader in the Society for Louisiana Irises, which she helped found in 1941 while teaching at what is now Louisiana State University in Lafayette. In her spare time, she experimented with native irises. Researchers began conducting controlled hybridizing in earnest during the early 1940s, and they've since produced a spectacular array.

Not knowing whether the Louisianas would thrive in Texas, Caillet nevertheless brought her beloved plants when she retired to her family's summer property on the shores of Lake Lewisville, about 40 miles north of Dallas. Thrive they did, and her garden has since become a laboratory of sorts for testing hybrids.

Last fall Timber Press published a second edition of "The Louisiana Iris: The Taming of a Native American Wildflower" ($34.95), which she co-edited with J. Farron Campbell, Kevin Vaughn, and Dennis Vercher.

Caillet's awards include the Stella Chapman Memorial Award from the Iris Society of Dallas, the 1983 distinguished service Medal from the American Iris Society; and the 1988 Distinguished Merit Award from the Society for Louisiana Irises.

Versatile plants

Caillet's garden in drought-prone Texas has proved that it's easy to grow these hardy plants in ordinary soil as well as in wetlands. Word is also getting around that Louisianas are not just for Southern gardens. And they're not just for soggy sites, either, although they generally grow taller in a pond or consistently moist site. During hot, dry months, she uses a soaker hose. Those in her pond need only minimal maintenance.

Of the five species of Louisiana iris, Iris brevicalis is the best choice for Northern gardens because it blooms the latest in the season, Caillet says. For that reason, it is not the best choice for Southern gardens. However, she encourages gardeners to experiment and determine the best choices for their landscapes through trial and error.

When 600-plus members of the American Iris Society toured Caillet's garden last spring, many expressed delight at her technique of interplanting irises with other beautiful bloomers.

Among the plants that complement the Louisianas during peak bloom: poppies, penstemon, old-fashioned petunias, larkspur, spider lilies, spiderwort, coreopsis, prairie phlox, daisies, and Swamp Rose shrubs.

Other plants that complement the spring show are native Texas redbud trees, pearl bush, mock orange, and a pink-flowering quince.

"You need to use irises, not just set them out in rows," Caillet says.

Each spring her neighbors on Cedar Pine Lane expect tour groups to arrive by the dozens. Horticulturists and photographers stop by Caillet's place, and she freely shares advice, cuttings, seeds, and plants. In fall, she plants new varieties for further study; those that arrive from Australia, however, must rest in pots for a year to adjust their blooming cycles to the Northern Hemisphere.

Every year for the past four or five years, Caillet has vowed: "I'll probably quit the tour business after this year." But this spring she's hosting nine groups. Friends and family members help out, but it's always Caillet who stays out the longest, talking with visitors and explaining the ruffled types, the recurved types ("they show better in a garden"), and the latest research.

Gardening comes naturally to Caillet. Not surprising, considering she's related to Julian Reverchon, a French botanist who helped found La Reunion Colony on the banks of the Trinity River at what is now downtown Dallas. Reverchon Park in Dallas is named after Julian, who was Caillet's great-uncle.

John James Audubon is credited with giving Louisiana irises their name, but it's Marie Caillet who has given them fame. Over the years, hybridizers have named selections in her honor: Marie Caillet, Charles Marie, Marie's Choice, Professor Marta Marie, and Little Caillet.

If you plant Louisiana irises this fall, your lagniappe is bound to flourish beyond your garden's borders. Rhizomes will divide and multiply, and in a few years, you can count on a Mardi Gras celebration of blooms.

Finding and growing Louisiana irises

Your site should get at least a half day or more of sun; six to eight hours is ideal. Louisiana irises thrive in constantly moist conditions - including water gardens and bogs - but they also perform well in ordinary soil if they get sufficient water all year.

Transplant rhizomes in early fall, planting about 1 inch below the soil's surface. Mulch with pine needles, pine bark mulch, compost, or peanut shells. Louisiana irises prefer acidic soil, but they'll also thrive in a neutral pH.

Clay soil isn't a problem because it holds water. Sandy soils, though, need to be amended with organic material such as rotted compost, mushroom compost, alfalfa pellets, or shredded leaves to aid water retention. Keep the planting damp until the irises are established, then water and mulch as needed to keep the bed moist and roots covered. Unlike bearded irises, Louisianas welcome overhead watering.

If you live in a drought-prone region, use a soaker hose to supplement natural rainfall and to conserve water.

Mulch with pine needles, pine-bark mulch, compost, or peanut shells. Mulch not only conserves moisture and keeps rhizomes cool, it protects the rhizomes from sunscald. Unlike bearded irises, which produce better blooms if their rhizomes are exposed to springtime sunshine, Louisiana irises prefer conditions that replicate their native habitats: swamps and boggy sites with plenty of organic mulch.

For more information

Society for Louisiana Irises 514 Garenne Road Lafayette, LA 70508 (Include a stamped, self-addressed envelope for a reply.) E-mail: AuBoisBourque@aol.com

Mail-order sources

Louisiana irises are not generally offered in local nurseries. Mail-order specialty nurseries are the best sources. They include:

Louisiana Nursery, 5853 Highway 182 Opelousas, LA 70570 (337) 948-3696 Website: www.louisiananursery.org Ask for the iris catalog, which costs $4.

Bay View Gardens 1201 Bay Street Santa Cruz, CA 95060 Catalog is $2.

Redbud Lane Iris Garden 2282 N. 350th Street Kansas, IL 61933 (217) 948-5478 Catalog costs $1.

Iris City Gardens 7675 Younger Creek Road Primm Springs, TN 38476 Phone: 800- 934-4747 E-mail: icity@msn.com Catalog is free.

Bois d'Arc Gardens 1831 Bull Run Road Schriever, LA 70395 (504) 446-2329 Catalog costs $1.

(c) Copyright 2001. The Christian Science Monitor