Plant iris as soon as you receive your i order. Early planting helps plants get established before winter. A sunny, well drained location with at least a half day of sun is recommended for iris. Plant the rhizome with the top just below the surface of the soil (about a half inch) and make sure to pack the soil lightly so there aren't any air pockets around the roots. Irises grow in any good garden soil. When planning out your iris garden make sure to keep the distance of 18" to 24" between each iris variety. As the plants grow and increase each year.
Newly set plants need to be kept moist to get their root systems established. Do not keep them really wet as this will promote rot. Established plants can go extended periods without water in the summer months. Let the soil dry out to a depth of 1" to 2" before watering. Do not use high nitrogen fertilizer. A good fertilizer for iris is 10-10-10. Do not over fertilize. High nitrogen fertilizer or over fertilizing increases the chance of rot. Irises should be fertilized a month after bloom and in early spring (about 6 weeks before bloom.) Bone meal, potash and super phosphate are all good things to add to the iris garden.
Divide iris clumps in July or August every 2 to 4 years depending on size of clump and how crowded the clump is to other iris clumps. Dig the entire clump out of the ground. Get as much of the soil off the roots as possible either by washing or shaking off the dirt. Cut off the outer healthy rhizomes with leaves and discard all of the bigger rhizomes without leaves. The newly planted rhizomes should be kept damp (not wet) until they are established and the plant is sending up new green leaves.
Reblooming Iris are planted and cared for the same as once blooming iris. Extra fertilizer and watering frequently will heighten the chance of rebloom.
Irises should not be cut back since their plant food is stored in the leaves. The only time it is recommended to cut the leaves is either when transplanting or if the leaves are old or diseased. Old flower stalks should be cut off next to the rhizome after bloom. Keep your iris free of weeds by hoeing which helps to keep the soil loose and aerated.