During late summer the buds for next year's bloom are formed. It is important to plant the iris early enough to avoid cold damage to these buds. Before planting, work the area where the iris are to be planted to a depth of at least 10 inches. Prepare the soil two to three weeks before planting to allow some settling. A well prepared soil bed will result in better iris growth and more blooms.
Plant iris rhizomes just below the soil surface in a good soil.
In heavier soil, plant with the rhizomes exposed slightly to prevent rotting. Roots should be buried to provide good anchorage. When preparing to plant iris, dig a shallow hole large enough to accommodate the rhizome or rhizomes that are available. Leave a cone or ridge of soil in the center of the hole. Don't allow the roots to clump together.