In one of my previous posts I discussed the use of Japanese iris for wet spots in your yard. The 
Japanese iris can be difficult to grow if not watered well. Louisiana irises also enjoy moisture, but are a little more forgiving of lack of moisture than the Japanese iris. These beardless irises are a great choice for bog and water gardens and can be grown in most areas of the country.
For best blooms, plant about an inch deep in half to full day of sun in slightly acidic soil without competition for moisture with trees or plants with large root system. Fertilize with the same fertilizer that you use on azaleas or alfalfa pellets, or three month slow-release pellets or 15-15-15, in the early spring and again after blooming in . Remove the bloom stalks after flowering and cut the foliage down to just a few inches in early winter. Mulch well. This protects the iris from drought as well as freezing temperatures. Addition of pine bark or pine needles will help with acidity.
If you plan to use the iris in a water feature, place the rhizome in an 18″ diameter pot. The depth of the pot in the water should be at least 8″ inches with the rhizome planted about two inches from the surface of the soil.
Rhizomes can be divided, ideally in the fall which is right now. It’s not nice to dig and relocate right after blooming, but if it is necessary, keep the transplants moist. In digging the irises, it is an easy matter to break off the new plants. Since offsets form in the winter or early spring, fall division allows the new plants to grow to sufficient size before being separated from the mother rhizome. The mother rhizome won’t bloom again, so you want to dig or buy one that has offsets or baby plants growing from it. An offset is those little bumps that appear on the side of the rhizome or that long bulb thingy that the leaves grow out from. These new baby plants will bear your new blooms next year.
You can take the old tired mother rhizome and make it form new baby plants by cutting Momma into two or three inch sections. 
Place it in a mixture of sand and vermiculite, or sand and peat, or potting soil. Cover the rhizome section with a quarter inch of the planting mix and keep moist. It is helpful to have treated the rhizome cuttings by immersing them for about ten minutes in water and ten percent bleach to prevent any fungus that might cause the cuttings to rot. The baby offsets will form along the cut edges of the Momma plant. When the baby plants get to be five or six inches long and have good roots, plant Mother and the babies in a sunny moist area.
