Louisiana Iris

by Paul W. Gossett

If you have lived in Louisiana and any of the Gulf Coast states you might have heard of an iris called the Louisiana Iris. They belong to the subsection Apogon (without beard or beardless), series Hexagonae of the genus iris. They consist of five species: I. hexagona, I. fulva, I. brevicaulis, I. giganticaerulea, and I. nelsonii. Most are native to a limited area of south central Louisiana and the Gulf Coast marsh areas from Texas to Florida. But, now are being grown in almost all parts of the United States, Canada, Australia, New Zealand, as well as other parts of the world.

John James Audubon was the first to use the term Louisiana Iris, when he used it referring to a group of swamp dwellers. He painted an iris as part of the background for the Purula Warbler, and in the text referred to the iris as a Louisiana Iris.

There were many early collectors and growers of Louisiana Irises, particularly in the vicinity of New Orleans. Near New Orleans the irises grew in great numbers in a wide variety of colors in the wild. Today, because of the many hurricanes to hit the region, and rural development of the area the irises have almost disappeared from the wild. There are still a few areas in the swamps on private property where you can see them growing in the wild.

Louisiana Irises come in a wide variety of colors and flower forms and no one form is preferable over the other. They are very easy to grow and grow well in the Tulsa area.

The following are some general culture facts for the Louisiana Iris in the Tulsa area.

  1. Planting Time: September 1 to Mid October. Try to plant early enough before cold weather sets in, to allow the roots to establish themselves.
  2. Location: Need sun to bloom well but, some summer shade is good. Beds should be low to hold water as they like to grow in water and mud. Borders of boards, bricks, rocks helps hold moisture as well as mulch materials, because mulching is an essential part of the culture of Louisiana’s. Plant rhizomes at or slightly below ground level and with a layer of mulch or soil in summer, especially in dry hot climates when planting in full sun. If planting in a pond, plant around the edges and DO NOT submerge the foliage.
  3. Soil: Prepare beds at least a month in advance. Dig in peat moss, compost, straw and/or rotted manure to loosen soil and hold moisture.
  4. Fertilizer: Louisiana’s are heavy feeders. Dig in a general fertilizer like 8-8-8 or 10-20-10 when preparing a bed. Add a side dressing to old clumps after they bloom or early fall. An acid type (Camellia fertilizer), liquid or slow release is good. Superphosphate in late winter or liquid miraacid will promote better bloom and stronger stalks. Lack of fertilizer results in small rhizomes, poor increase and poor stalks with fewer blooms.
  5. Water: Will grow in beds with other flowers and normal watering, but all do better with more than average water. Remember that Louisiana’s came from marshes/swamps of Louisiana and had lots of water in the spring and less water in the summer. Keep moist after digging and transplanting. They need spring rains or watering before they bloom and in early fall when they begin to grow.
  6. Transplanting: Rhizome length and density of increase varies with variety and culture. Most clumps need to be divided about every other year for best results. Leave enough space between plants to allow for long rhizomes that “travel” as much as a foot from the old rhizome. Cut the foliage back to about 9 inches and water to settle the dirt around the roots. If planting along a creek or shallow pond, pin the rhizome to the ground with a brick. Old rhizomes, with some care, will produce increases for additional plants.
  7. Winter Protection: Mulch with pine needles of oak leaves before the snow covers the ground. Late blooming varieties will have less cold damage to stalks and buds.
  8. Problems: Leaf spot looks unsightly but does not harm the plant, can be treated with using a fungicide. Yellowing of the foliage (chlorosis) is corrected by adding iron or sulphur to the soil or use a spray for faster results. Leaf miners that cause white streaks in the foliage can be treated with a Cygon spray. Slugs can be treated with slug bait.
  9. General Care: Cut spent bloom stalks after bloom to prevent seed pods from forming. Remove dead leaves only after they are ready to fall away from the plant. Some varieties stay green all summer and some go completely dormant. Most, if kept well mulched and watered, will remain green all summer. Provide some shade over rhizomes in the hot summer to cut down on sun scald that reduces increase and future bloom. Plant other plants like daisies, coreopsis, four o’clocks, or any others that will produce a little shade.

Now, I guess you are saying where can I get some of these Louisiana Irises. The Tulsa Area Iris Society holds a Fall Rhizome Sale at the Tulsa Garden Center in mid September each year. Contact the Tulsa Garden Center for the telephone number of a person to contact, or visit www.Tulsairis.org for updated information.

In 1941 the Mary Swords DeBallion Iris Society was formed in Lafayette, Louisiana. Today it is known as the Society for Louisiana and based in Lafayette, Louisiana and holds an annual convention each year, go to the SLI Web Page at www.louisianas.org for more information.

A couple of books that I recommend reading would The Louisiana Iris by Marie Caillet and Joseph K. Mertzweiller, The Louisiana Iris Second Edition by Marie Cailet, Kevin Vaughan, and Farron Campbell, and The World of Iris by Bee Warburton and Melba Hamblen. They can be found at the Tulsa Garden Center Library or the Tulsa City-County Library.