How to Plant Bearded Iris
The late-May garden wouldn’t be complete without a stand of bearded irises dancing in the breeze. Their rich, velvety petals, intoxicating fragrance, and cascading beards make my gardener heart swoon. But it’s not only the appearance or fragrance of these flowers that makes me love them. Rather, it’s knowing the “who” behind each bloom that keeps me coming back for more.
It seems that every gardener has an origin story to accompany their bearded irises. Perhaps they inherited a box of canary yellow iris from a neighbor, traded rhizomes with a fellow garden enthusiast, or snagged unmarked divisions from a roadside stand. Whatever the case may be, I think gardeners love bearded irises not just for their ruffly blooms, but for the stories the flowers carry, and the memories of loved ones that live on through their petals.
Bearded irises are grown from rhizomes that sit on top of the soil surface. These plants originate from areas with very hot summers and very cold winters which makes them exceptionally hardy garden plants. When planting, it’s important not to bury the entire rhizome. Instead, leave the top of the rhizome exposed so it can become sunbaked. When planted in the proper location and at the correct depth bearded irises can live for generations.
How to Plant Bearded Iris
Bearded irises should be planted in the late summer or early fall, so they have at least six weeks to get established before the first hard frost.
Select a planting site that receives full sun and has well-draining soil. Bearded irises will not thrive in heavy, waterlogged soils and excessive moisture can result in rot and disease. Iris rhizomes should be planted at or just barely below the surface of the soil. After planting, you should still be able to see the very top of the rhizome.
Start by loosening the soil to 12” deep. Next, dig a shallow hole and slightly mound the soil in the center. Position the rhizome on top of the soil mound and spread out the roots on either side. Firm the soil around the roots, remembering to leave the top of the rhizome slightly exposed. Finish by watering in the rhizome and continue to provide a consistent supply of moisture until the roots are well established. However, once the weather turns cold, keep the soil as dry as possible. Unlike other plants, bearded irises should not be mulched, but it’s still important to keep the area free of weeds and debris.
Bearded iris spacing should be based on your desired display, and how often you want to divide the rhizomes. Irises planted 24″ apart will gradually fill the space and not need to be divided for many years. Irises planted 12″ apart will provide an abundant flower show more quickly but will need to be divided sooner.
How to Divide Bearded Iris
Bearded irises should be divided every 3-5 years to maintain good plant health and abundant flowering. The best time to do this is mid-summer, about a month after the flowers have faded.
Start by digging out a bearded iris clump and placing it on a tarp for dividing. Next, gently separate the healthy new rhizomes from the older, less-productive rhizomes located at the center of the clump. Discard any rhizomes with holes or soft spots and throw away the oldest part of the plant which will be less vigorous than fresh, new sections. Then, use scissors to cut the foliage back to one-third of its original height. Replant only the healthiest, most vigorous rhizomes with 3 to 4 leaves, allowing about 12″ of space between the clumps.
How to Harvest Bearded Irises for Cut Flowers
Although bearded irises have a short vase life, there are a few tricks to help extend their beauty inside the home. Like all cut flowers, it’s important to harvest irises in the early morning, or late evening and place the stems immediately into clean water. Since irises are easily bruised, they should be harvested in “pencil stage” when the blooms are still closed but the color is evident. Irises harvested in pencil stage will open 24-48 hours later and will have a vase life of approximately 3 days. Depending on their intended use, you can remove lower flowers as they fade allowing the blooms higher on the stem to open in the vase.
You can also harvest irises fully open. However, this generally results in a vase life of only 1-2 days and the delicate petals can be easily bruised as you are handling them.
How to control common iris pests
In the eastern US, the iris borer attacks all types of irises. Although this pest may not kill the plant, it can cause streaked or spotted leaves and makes the rhizomes mushy. This borer is a pinkish caterpillar that burrows into the leaves and then starts moving down into the root zone. As the caterpillars feed on the rhizomes, the plants are exposed to a host of diseases including bacterial soft rot and leaf spot. To avoid iris borer, trim back all the foliage in the fall after the first heavy frost. Destroying the foliage will eliminate many of next year’s eggs. Additionally, when dividing plants, examine the rhizomes for signs of iris borer damage and remove any affected parts.
Learn more about bearded irises by watching our video on How to Plant and Divide Bearded Iris. You may also want to read our article All About Bearded Iris. Shop our complete selection of bearded irises HERE.