Bearded Iris

Bearded Iris- Bold and Beautiful
by Kim Willis

Bearded Iris, sometimes referred to as German iris, have some of the most colorful flowers, [as well as colorful names], in the garden. Bearded Iris are hardy and easy to grow and good for beginning gardeners. Bearded Iris are also a collectors delight, with hundreds of varieties on the market. For a splash of color in late spring and early summer, plant some Bearded Iris in your garden.

Bearded Iris have thick, “sword- like” leaves. The Bearded Iris flower has six petals. Three petals stand upright and these are called the “standards.” The other three petals droop downward and are called the “falls.” Each “fall” has a group of hair-like growths near its base called the “beard.” Each Bearded Iris can be all one color- beard, falls and standards, or each part can be a different color. The flowers appear at the end of long stalks in clusters. Some varieties are fragrant. Bearded Iris begins blooming in mid spring with the dwarf and intermediate varieties, and continues into early summer with the border and tall varieties. Some new varieties may re-bloom in fall when the season is long and mild.

Growing Bearded Iris

Bearded Iris are hardy from zone 3-9. The best time to plant Bearded Iris is late summer or early fall. Bearded Iris may be sold in pots or more commonly, as bare rhizomes. A rhizome is a long, fleshy looking thing with roots coming out of the bottom. It will generally have a few leaves, called a fan, that have been cut to 3-4 inches. Don’t worry if the fan is dry and yellow, as long as the rhizome is firm and plump. Mushy, soft, or shriveled, dry rhizomes, or those with holes in them should not be bought. Long, branching iris rhizomes with two or more fans will give you bigger plants and are more likely to bloom the first year. About 60-70% of Bearded Iris bloom the first year after they are planted.

Bearded Iris need full sun. They need well drained soil, and do well with little water after they are established. Iris benefits from a small amount of low nitrogen fertilizer in early spring as growth starts. For the best chance of getting re-blooming varieties to actually re-bloom, fertilize them again after the first bloom has finished, and give them a little water if the summer is dry.

To plant Bearded Iris rhizomes dig a trench a few inches deep and make a little mound of soil in it. Place the rhizome on the center of the mound and fan any roots out along the sides of the mound. Then re-fill the trench. The top of the rhizome should be just barely covered in soil. In heavy clay soil the top of the rhizome can even be left exposed. Bearded Iris will not bloom if they are planted too deeply. Plant the rhizomes 18-24” apart. The first year after planting the Bearded Iris rhizomes should be mulched with straw, oak leaves or other material that doesn’t mat down. This is to prevent them from being heaved out of the ground before the roots are established. Remove the mulch as soon as the weather begins to warm. Bearded Iris should be kept weed free and they are one plant that should not be mulched. The tops of the rhizomes need air and sun for the plants to do well.

To keep your Bearded Iris plants looking their best remove each flower as it dies. When all the flowers on a stalk are finished blooming cut the stalk down as close to the base of the plant as possible. Remove any leaves that yellow or have spots and streaks on them, and cut all the leaves off close to the ground after frost in the fall. This helps keep disease and pests from over-wintering.

Bearded Iris needs to be divided every 3-4 years for best bloom. Over time the center of the clump stops blooming and if the plants are too crowded, all may stop blooming. Dig up the clumps after they have bloomed, wash off the rhizomes and cut apart the clumps. Leave a nice section of firm rhizome with a “fan” or two. Cut the leaves on the fan back to a couple of inches. Discard the old, woody and dry looking pieces of rhizomes from the center of the clump and also discard any soft, black mushy pieces or rhizomes with holes bored in them. Then re-plant your divided rhizomes and share the excess with other gardeners.

In some areas Bearded Iris may get Iris Borer. A night feeding moth lays eggs on the plants near the leaf base. These hatch into caterpillars which first feed on the leaves, then move into the rhizomes. They are big, fat pink things that eat the inside of the rhizome. This leaves the rhizomes more susceptible to bacterial rot, which turns the rhizomes black and mushy. To keep Iris plants healthy remove damaged and diseased rhizomes, cut back and remove leaves before winter, and don’t over water.

Choosing Varieties.

The iris family contains many species, the Bearded Iris we grow in our gardens are hybrids of some of those species. There are hundreds of varieties of Bearded Iris with names as colorful as their flowers. In catalogs they are generally grouped by height, flower size and bloom time. There are varieties of Bearded Iris that grow only 6” tall and others that grow 3’ or higher. I am not going to list specific names, as there are so many.


Using Bearded Iris

Bearded Iris are usually grown as part of mixed borders. Small varieties can be grown in rock gardens or even in pots. Pots should be sunk into the ground to over winter in cold areas.
The rhizomes of iris are dried and powdered to form orris root and dried rhizomes are also used to make perfumes.

copyright Kim Willis 2008