 | In Greek mythology, Iris is the name for the Goddess of the Rainbow. In various myths she is said to use wings of gold to relay messages between Heaven, Earth, and the Underworld. One myth states that every time she places one of her feet on the Earth, iris flowers pop up in a rainbow of colors – this is how the iris got its name.
Irises are colorful and hardy perennials that can thrive in every type of environment. Because they have such a wide variety of colors and possess such ornamental flowers, they make a great addition to anyone’s garden. Below is a guide to planting and maintaining bearded irises.
First, we need some basic information. There are two main groups of irises: those grown from bulbs, and those grown from rhizomes. The rhizome group then has two further classifications: bearded, and beardless varieties. This article will deal with the bearded iris since it is the most common.
Three of an iris’s six petals point upward (called standard petals), and the other three point downward (called falls). The bearded iris received its name because of the small hairs or fuzzy lines that run down the center of the falls.
Throughout North America, bearded irises are usually easy to grow. The only regions that are difficult are the humid ones, such as Houston, Miami, or New Orleans. The best way to find irises with growing conditions in agreement with your area is to visit a nursery or gardening center and ask someone about them; then simply pick the iris that is most appealing to you. And remember to always wear some form of hand protection when handling irises because the sap is known to irritate the skin.
Irises grow from a fleshy, horizontal plant stem called a rhizome. It’s usually around a half inch thick and about three inches long with short roots on the sides. The rhizome stores the food made by the iris leaves; and each year buds develop from it with additional flower stalks and leaves. Keep in mind that the health and beauty of your irises is fully dependent on the state of health of the rhizome. When you receive your rhizomes make sure they have plenty of ventilation until you can plant them, never allowing them to get too hot. It’s best to plant them as soon as possible, but rhizomes can survive out of the ground for about two weeks.
Make sure the area you select for planting your irises will get plenty of direct sunlight; about six hours of light is recommended for proper blooming. The soil should be well-draining and have a pH measurement close to neutral; and avoid having too much clay in your soil, which will allow the rhizome to rot. Add a healthy amount of peat moss or compost for best results and use a 5-10-10 fertilizer. If you need to get your soil near the neutral level, just add limestone. Remember that even though potash, phosphorus, and nitrogen are important for healthy irises, too much nitrogen in the soil will make them rot in wet seasons. Rototilling your iris bed to ensure the fertilizer and compost is well mixed is a good idea before planting.
You can plant bearded irises anytime from midsummer to about a month before the first frost strikes. Usually this will be between July and October. Make sure any other plants in the area won’t be shading the rhizome since it needs plenty of direct sunlight. Dig a shallow hole big enough for the rhizome. Take some of the soil you removed and make a mound in the center of the hole. Put the rhizome on the mound and let the roots drape down over the sides. Push the rhizome down a little bit to make sure it’s set, but don’t go too deep. Fill the rest of the hole, being careful not to allow air pockets, which will promote rotting. It is better to place the rhizome a little higher up than have it too deep. Next, water to get the soil moist, but don’t waterlog it; never let rhizomes stand in wet soil. If you’re planting a lot of the same type of irises, you can lay them out in a circle (8 to 11 inches apart) with the leaved rhizome end pointing out.
If your plants have a lot of foliage, they won’t require much fertilizer. But if they do need some, never place the fertilizer directly on the plants because it will burn them.
About every three years your rhizomes will need to be dug up and divided to avoid overcrowding. The quality of your blooms will deteriorate if you don’t. Simply pry up the rhizomes with a shovel, cut the clumps apart, keeping the ones that are thick and firm while discarding the leafless ones. (Even if your old rhizomes feel healthy and firm, they most likely will have lost a lot of their flowering capacity and should be thrown away.) Next, cut the leaves to a length of six inches, then put them somewhere to air-dry over night. Add more compost to the soil before replanting the next day.
In late autumn, cut the leaves back to two-thirds their original length. Remove any dead foliage, which will help eliminate snails that enjoy chewing holes in the flowers. Be sure to mulch before it snows if you’re living in a colder area.
If your irises are not blooming as they should, it could be due to several things, or even a combination of them: they may be getting too much shade; they could be overcrowded; there may be too much nitrogen in the fertilizer; the rhizomes may be planted too deep; or the soil doesn’t have enough nutrients. Overcrowding is generally the most common cause of plants not blooming.
The most destructive and most common pest to bearded irises are borers. In the fall, moths lay eggs in dead flower stocks of plants. These eggs hatch and the tiny caterpillars bore down through the leaves and eat their way into the rhizome. This allows bacteria to invade and cause “soft rot.” To get rid of borers, dig up the rhizome and cut out any infected parts and discard. An insecticide can be used to kill them in the spring. And each year after the first frost, be sure to clean up any dead leaves or plant debris, which will do away with any moth eggs. Also, inspect your leaves occasionally for any “tunnels” or notches on the leaves. If you find any, kill the larvae inside by pinching the leaves together. Be sure to disinfect your tools with denatured alcohol after dealing with soft rot because it can easily spread.
If the leaves and flowers of your irises look discolored or are irregularly shaped, they may have a viral disease called “mosaic” which is caused by aphids. The solution is to destroy all infected plants and use an insecticide for the aphids.
Two other general tips: Always keep your iris beds free of weeds and old leaves to allow plenty of circulation. Every fall treat them to a teaspoon of bone meal.
The above rules are really just tips on how to get your irises looking especially fantastic, since irises are extremely hardy (they are almost entirely drought resistant, for example). Some people have planted irises, breaking all the rules in the process, then provided very little care for them and yet they have still thrived!
The most popular irises are usually the darker varieties -- blacks, purples and blues; in addition to being aesthetically pleasing, they are also more hardy and disease-resistant. Pink, yellow, and orange irises are more fragile. Some newer types of bearded iris bloom two to three times a year, but most only bloom once.
Here are a few of the more popular ‘tall’ varieties (around 36 inches and up):
- "Before the Storm" - a fragrant black iris
- "Dusky Challenger" - a late blooming purple iris (some say weather affects the color of this one)
- "Champagne Elegance" - a pink iris
- "Edith Wolford" - a purple and yellow iris
- "Honky Tonk Blues" - a blue and white variety
Here are a few of the more popular dwarf varieties (around 10 inches):
- “Carrot Curls” - an orange iris
- “Baby Blessed” - a lime-yellow iris
- “Cherry Garden” - a reddish-purple variety
- “Banbury Ruffles” - a purple iris
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