Irises are great flowers to add to a home garden because they go well with other plants and can be cut and added to fresh flower bouquets. Irises have an underground root system called rhizomes. Iris rhizomes and other bulb-like structures such as corms and tubers often are classified under the generic term "bulb," which refers to any fleshy underground root structure. No matter what you call them, take proper care of your iris bulbs (rhizomes) for them to grow and thrive year to year.
Plant iris bulbs in late summer or in the fall. Plant them in rich, well-draining soil just below the soil's surface. Add about 1 inch of water.
Store unplanted bulbs in a cool, dark spot. Dust the iris bulbs with a sprinkle of sulfur to help prevent rotting and to discourage insects. Place the iris bulbs in a mesh bag or open container to allow for circulation.
Cut off the foliage only after it dies away after the first frost, not after blooming has finished.
Cover the iris bulbs with 2 to 4 inches of organic mulch to help prevent the soil and bulbs from a freezing-and-thawing cycle during the winter months.
Divide irises when the garden becomes overcrowded, which can cause the irises to produce fewer bloom than previous years. Dig carefully with a garden fork around the plants to lift the bulbs out of the soil. Cut them with a utility knife, leaving a crown (the part where the plant grows) on each division. Replant immediately as described above.