Drivers cruising down Interstate 310 can see a bountiful bloom of native Louisiana irises peaking up from the swamp. Gabriel LoCoco, a horticulture extension agent with the LSU AgCenter of St. Charles, said April is the peak month for iris blooms in our part of the state.
“A native Louisiana iris is classified as one of five species – abbeville red, copper, dixie, giant blue, and zigzag,” LoCoco said. “They get the title of ‘Louisiana iris’ because this is the only place where all five species occur together.”
LoCoco explained that on the east bank of St. Charles Parish the swamps are filled with the lightly colored and upright giant blue irises.
“A trip down the bayou to Des Allemands will show off some orange-hued copper Irises, the dainty purple and yellow zigzags, and the bold dixies,” he said. “While August and September are the best times to plant Louisiana irises, the spring gardening season is when you are most likely to find them available in your local nurseries. This is one of the plants that you’ll have to go against the grain to get established in your garden if you want to preview them while shopping. Take note of neighbor’s selections, what performs well in your part of the parish, and what you like.”
LoCoco said while Louisiana irises can be reliably planted in the spring, one caveat of springtime planting is the rise and fall of the foliage.
“As the days get longer and hotter, the plant takes on summer dormancy,” he said. “In June, July, and August, beds planted with irises can become weathered. Remove dead foliage as needed.”
September to May is the active growing season for this plant.
“Though some green foliage remains throughout the year, the active growing season brings the most striking color,” LoCoco said.
To plant Louisiana irises, he added, gardeners should pick a location that gets direct sun for most of the day, as those conditions will trigger heavier bloom in April.
“Pick a place that can stay moist for most of the year, and a spot that will allow the plant to spread,” he said. “Soil high in organic matter and nutrient availability will also encourage heavier flowering. Plant potted irises and rhizomes just below the soil surface in your desired location and keep them watered during their active growing season. Take note that irises will spread in the direction they face.”
LoCoco said planters should apply a two-inch layer of mulch to plants to prevent sun-scalding and help keep moisture in.
“Typically, water is plentiful during this time of the year and that is what makes them such a great candidate for our gardens,” he said. “Fertilize your Louisiana irises with an all-purpose fertilizer between September and February. Follow the label recommendations for application rates.”
The LSU AgCenter Extension Office of St. Charles is offering a Louisiana Master Gardener course to residents of St. Charles, St. James, and St. John the Baptist parishes this fall. The course will run for 12 weeks and cover essential gardening information and provide participants with volunteer opportunities to master their skills.
LoCoco described the class as a college-entry level course in gardening. Following the course, monthly meetings to continue education will be held.
To learn more about this course, call 985-785-4473.