Plant an iris by choosing a location with full or partial sun, planting during the summer, using well-drained sandy or loamy soil, and fertilizing it as needed. Make sure that the plant's rhizome is partially exposed during planting.
First, choose a sunny location for the iris, as it requires sunlight for full blooming. The soil needs to be well-draining with a neutral to slightly acidic pH level. Before planting, loosen the top 15 inches of soil, and work in 4 inches of compost to improve drainage and add nutrients. Plant no earlier than midsummer.
Dig 10-inch diameter, 4-inch deep holes that are at least 1 foot apart for each iris plant. Build up a ridge along the center of the hole on which to rest the plant's rhizome so that it has some light exposure. Place the iris in the hole, spread out the roots, and arrange the rhizome on the ridge while tamping soil into the hole.
Water the iris immediately after planting, followed by a low-nitrogen fertilizer. Afterwards, feed it once a year in the early spring. Keep the rhizome partially exposed at all times. Avoid covering it with mulch, as it can lead to root rot. The plant can be mulched in the spring with a very thin layer of organic material that doesn't touch the stalk or rhizome.