Iris flowers require well-drained soils, significant moisture and specific fertilizer depending on the soil type. Maintaining Iris beds is also paramount to the health of the flower. Iris flowers must also be divided or thinned every few years to avoid overcrowding.
- Plant and water
Make sure the soil is well-drained and plan the Iris flowers on a slip or raised bed to ensure adequate drainage. Plant Iris flowers in July through August to ensure that the roots are established before the growing season ends. Choose a location that receives at least six hours of sunlight per day. Newly set Iris flowers require substantial moisture. Specific watering amounts depends on the climate and soil type, but deep watering at long intervals is desirable.
- Fertilize the Iris bed
Use bone meal, 6-10-10 or superphosphate fertilizers. A light application in the early spring and a subsequent light application six weeks after bloom ensures healthy growth. Avoid using nitrogen-rich fertilizers.
- Divide and transplant
Iris flowers must be divided or thinned every three to five years. Dig the clumps with a spade or garden fork, and divide the rhizomes by pulling them apart. Wash the soil off the rhizomes an destroy the borers and smelly or soft plants. Trim the leaf blades so that they are 4 to 6 inches long. Replant the divisions, setting the rhizome above the fine roots.