Iris Culture and Planting
Iris thrives in a well-drained neutral to slightly alkaline soil, but is generally tolerant of most garden soils. At least six hours of sun are needed for vigorous growth and flowering. The preferred time for planting is in the fall to give the roots time to develop over the winter and store up nourishment to support spring blooming. Feeding in early spring with a balanced garden fertilizer like 10-10-10 or 12-12-12 is recommended. The stiff spear-shaped leaves grow in fans from individual rhizomes. They develop into semicircular clumps as they age. Iris are hardy perennials and need little more than a light mulch for winter protection. Some growers prefer to trim the leaves before winter. The rhizomes from which the iris grow, are elongated underground systems thickened by food deposits. They produce flowering plants above and roots beneath to anchor and nourish them. It is important when planting the rhizomes to cover them with no more than one inch or less of soil. However, the rhizome should rest upon well-cultivated soil deep enough to allow the roots room to develop and spread. Water the new plants thoroughly, but wait until early spring to add fertilizer.