With over 200 species in this diverse group of plants, there is bound to be the perfect iris among them for your garden. In general, irises are low-maintenance and easy to grow. Their flowers come almost every color and bloom times vary depending on the species; some irises bloom in spring or summer, while others bloom in spring and again in fall.
All species of iris boast flowers that are intricate and detailed. The three lower, drooping petals are commonly referred to as the falls. The three upright petals are called the standards. All parts of an iris blossom are colorful and can have a variety of patterns. Bearded irises are especially noteworthy for being available in a rainbow of colors and forms. The foliage of irises can also be quite striking, with long, lance-shape leaves in an attractive gray-green color. Even when not in bloom, the upright foliage can add interesting texture to a garden.
Iris Care Must-Knows
Bearded and bulb-type irises need well-drained soil to thrive because they will rot easily in soggy conditions. Many of these species are native to rocky mountainsides where there is sharp drainage. If you are looking for a species to grow in moist soil, look for a Louisiana iris, Japanese iris, or a yellow flag iris. Because different irises need such different growing conditions, make sure to do a little research before planting so you can provide your particular iris with what it needs.
When it comes to sunlight, all irises need 6-8 hours of full sun for the best blossoms and foliage growth. In too much shade, growth may be more stretched and prone to flopping over, and the plants will be less likely to bloom.
Related: 4 Rarely Shared Facts About Irises
Bearded irises and other rhizomatous types will eventually need to be divided every 2-5 years. If it has been quite some time since their last division and your irises seem to be flowering less and less, chances are it's time for them to be divided. The best time to divide and replant most irises is late summer to early fall. At this point in their life cycle, irises are somewhat dormant and are resting up for their fall growth cycle to begin.
To divide your irises, carefully lift the plants out of the ground (a pitchfork works great for this), and carefully tease apart the individual rhizomes. Don't worry if you break a few roots or rhizomes, as they are pretty tough plants. If there is some fairly large foliage attached to the rhizome, you can cut it back by half (this helps the plant lose less water while recovering from all the dividing upheaval).
Once they are all separated, you can replant by digging a small trench and setting each rhizome on a small mound of soil, then fanning out the roots around it. Then, backfill with soil around the rhizome, making sure to tamp down any air pockets and bringing the soil level just to the top of the rhizome. Water your plants well. Give them a good drink once or twice a week for the first several weeks after planting until the new roots begin to grow.
Irises are fairly pest-free, but iris borers are their one nemesis. This bug does most of its damage around blossom time, often between mid-April and mid-June. They chew their way into the leaves and then burrow down into the rhizome, leaving behind a trail of frass, a powdery brown residue. Once at their destination, the borers can eat several rhizomes and make their way through an entire bed. Their damage also opens plants up to infection from bacterial rot, too. These insects are tricky to control as they are often hidden within the plant where pesticide sprays can't reach them. If you do find a damaged plant, dig it up and see if you can locate the culprits and dispose of them. The best method of control is often prevention, so make sure to clean up any debris around your irises in fall and early spring, which is where borers overwinter.