Plan to add bearded irises to your garden
Iris was the Greek goddess of rainbows. It also has been the subject of paintings by Leonardo da Vinci, Vincent van Gogh, Pierre Auguste Renoir and Claude Monet. It is no wonder the iris has remained one of the best known and loved garden flowers.
The bearded iris, also called German iris, is one of the most popular types. They flower in mid-May, are easy to grow and are extremely long-lived. There are varieties available offering blooms in any color of the rainbow - some solid; some bicolored. For gardeners searching for blue flowers, look no further than the iris family. One of my favorites is Devil's Lake. It boasts huge, 7-inch, dark blue flowers on tall stems.
Bearded irises require a location with well-drained soil and lots of sunshine. Their bulky rhizomes grow partly above the soil and will rot if buried too deeply or grown in soggy soil. Amend heavy soils with lots of organic matter before planting.
Irises growing in nursery pots can be planted throughout the growing season, but rhizomes are best planted in late summer to early fall. Be sure they are planted at least six weeks before the first hard frost so they have time for their roots to establish before winter. Plant them at least a foot apart. Position their rhizomes so they show above the soil and their roots spread downward in all directions.
Water them thoroughly after planting to help roots take hold quickly. Once established, they will only need supplemental watering in periods of drought. Two light applications of a low-nitrogen fertilizer or superphosphate are beneficial - one in early spring and another a month after they have bloomed.
The rhizomes of bearded irises grow horizontally, forming new sections until there is a solid mat of rhizomes. These should be divided every three or four years before they become overcrowded and more susceptible to diseases. Divide right after blooming or in late summer to early fall.
To divide, lift the entire clump, cut away and discard older sections, and replant newer pieces. Feed them after transplanting and water in thoroughly.
Bearded irises require very little care during the growing season. Rhizomes prefer to wear their birthday suits to bask in the sun so there is no need to apply mulch. Deadhead spent blooms and prune away dead or diseased foliage. In fall, trim leaves down to 4 to 6 inches. In winter, cover rhizomes with evergreen boughs.
Some bearded irises re-bloom in late summer or fall. Fertilizing encourages re-blooming. Watering during dry spells in the summer also encourages them to bloom again.
Immortality presents large, pure white flowers with lemon yellow beards in May and again in September. Summer Olympics is another re-bloomer offering lovely yellow blooms.
Iris borers can be frustrating for bearded iris growers. In spring, eggs laid in garden debris hatch. These larvae chew their way into iris leaves and head down toward rhizomes, where they eat the tissue inside. In summer, borers change into pupae that live in the soil until they become moths who lay eggs of the next generation.
The best way to reduce borers in the garden is to watch for signs before they get to rhizomes. Infested leaves should be destroyed. It is also easier to eliminate borers when they are defenseless moths.
• Diana Stoll is a horticulturist and the garden center manager of The Planter's Palette, 28W571 Roosevelt Road, Winfield, IL 60190. Call (630) 293-1040 or visit online at planterspalette.com. She blogs at gardenwithdiana.com.