The Louisiana iris is an easy plant to grow and care for when planted properly. That being said, there is a major misconception regarding these beauties. While they do grow well in bog environments and water gardens, they will also thrive in most garden beds when planted properly and regularly watered. I personally grow all of my varieties in beds and containers.
Our iris are all shipped bare-root. They are removed from the beds, trimmed, cleaned of soil, disinfected, labeled, and packaged in a moist wrapping so they don’t dry out completely during shipment. When they arrive at your location, please remove from packaging and either plant immediately and water them well, or place the rhizome in a shallow tub of water for no more than 48 hours prior to planting.
Your Louisiana iris should be planted in a bed with soil that is loose and rich in organic matter. Hard clay soils can dry out and become like concrete, preventing water from reaching the roots and leading to the eventual death of the plant. The area should receive at least 6 hours of full sun for proper blooming. Louisiana iris prefer an acidic soil, but can tolerate slightly alkaline soils to a degree. The average garden bed typically suffices. Water regularly during dry spells and they should perform well for you. While many people think of the Louisiana swamps when the Louisiana iris is mentioned, the fact is that these plants are native to a large portion of the United States. Louisiana just happens to be the area where all 5 of the species occur together.
Louisiana iris need to be planted with the top of their rhizome (large root structure) just below the surface of the soil. The feeder roots should be spread out into the soil below. Allow a couple of feet between varieties for the plants to spread as they will reproduce and spread. A couple of inches of mulch should then be placed atop the soil to help reduce weeds and maintain moisture. Your Louisianas will appreciate being thinned out every few years. Overcrowding can reduce flowering in my experience.
Fertilize your iris in Fall as they will begin putting in new growth and again prior to flowering in early Spring. A general purpose fertilizer such as 8-8-8 or 10-10-10 at a rate of 2-4 pounds per 100 square feet works well. Slow release granules are also beneficial and often include micronutrients which help.
Bloom stalks should be trimmed down to a few inches above the soil line after the bloom season unless you plan on collecting the seeds that are often produced. Leaving these stalks will only rob the plant of energy that it could use to produce offsets and multiply. Please be aware that any seeds produced will create plants that will vary from the parent plant and allowing them to go to seed could result in random seedlings popping up in your beds.
I don’t personally utilize Louisianas in aquatic culture, but they will work well in that manner. They are typically planted in pots of heavy soil, and placed in ponds with the container edge just below the surface of the water. fertilizer pellets can be inserted into the soil of the pot to help your iris acquire needed nutrients.