Bearded iris, also called German irises, have two sets of petals, one that grows tall and upright, and a second that hangs down from the base of the flower. The "beard" is a fuzzy yellow or white growth on the lower petals. German irises are big, showy flowers that bloom in the late spring or very early summer.
Planting Bearded Irises
Plant your bearded iris bulbs in late summer or early fall, as soon after getting them as you possibly can. If you can't plant them immediately, Dutch Gardens, a vendor of flower bulbs, advises that you take the packaging holding the bulbs into a cool place and open it up. Mist the bulbs with water, and repeat the process every day till you plant them.
Choose a place for your iris bed where they'll get at least 6 hours of direct sunlight every day.
Make sure the spot you choose gives your irises room to grow. Don't plant them close to other plants.
Spade up the dirt in your chosen spot well, digging at least 12 inches deep and 12 inches wide.
Spread enough compost over the soil to increase the overall depth by 4 inches.
Mix in some slow-release fertilizer---follow the package directions to determine the right amount for the square footage you're preparing.
Stir the mixture of soil, compost, and fertilizer up so it's well combined. Smooth out the soil so that it's level.
Dig one hole for each bearded iris rhizome, 2 inches deep and 10 inches wide. Separate the holes by a foot. Scrape up a ridge of soil in the bottom of each hole.
Put one rhizome into each hole, with the roots straddling the ridge of soil. Make sure the foliage at the top of the rhizomes points in the same direction.
Cover up each rhizome with just enough soil to reach the top of the fleshy part of the bulb.
Water the irises until the soil is wet but not soaking.
Caring for Bearded Irises
As they are establishing themselves, water the irises twice a week, but be careful not to leave them standing in water, which will rot their roots.
Once the irises are established, water them only during exceptionally dry periods.
Every four or five years, in August, divide the rhizomes. Dig each rhizome up and use a sharp, clean knife to cut it into several pieces, making sure each piece has some roots and some foliage.
Throw away the old rhizome at the very center of the cluster. Cut the foliage back to three to four inches high above the top of the rhizome.
Replant the rhizomes in the same way you planted the original bulbs and water them twice a week until they've re-established themselves.