When Jennifer Brennan went downstate for a family wedding last summer, her plans included a visit to her grandparents’ old farmstead where she would dig up the tall bearded irises that were hopefully still there.
“I got up early before the wedding and went to the farm to dig up the irises,” she recalls. “It was amazing. The tubers (rhizomes) had been buried under 8 inches of soil, but I was able to dig them all up, divide them among my dad, two cousins and me. They had been planted 75 years ago.”
Brennan, the horticulture information specialist at Chalet in Wilmette, would never tell a customer to plant bearded irises 8 inches deep. The instructions in catalogs and books all say to plant just under the soil surface with some of the rhizome showing. But plants don’t read the books and can live to astonish us. Brennan fully expects the rhizomes she retrieved to bloom this season.
The irises that Brennan brought back from downstate were the tall bearded types that grow 3 feet tall and bloom in late May into June. Iris flowers consist of three vertical petals, called “standards,” and three drooping petals, called “falls.” The bristly hairs on the falls are the so-called beards. There are dozens of iris types, some with beards, some without.
Boyce Tankersley, director of living plant documentation at the Chicago Botanic Garden, grows many kinds of iris at his Grayslake home and also at the Garden in Glencoe. “Everybody should grow irises,” he asserts. “They are one of my favorite plants and easy. They keep coming back.”
He is especially fond of the tiny early spring irises that pop up early with the crocuses. Two regularly available species are Iris reticulata and I. histrioides, which grow from bulbs that you plant in the fall. They look delicate but are “winter-tough and reliable” because they hail from the Republic of Georgia and the Caucasus, he explains. “You start with a couple dozen and they bulk up over time.” The photo (below) of Iris histrioides ‘Harmony’ at the Garden proves the point.
While growing iris is pretty carefree, classifying all the different types can drive one to distraction. Plant size, for example, may be 6 inches or 5 feet. Some demand wet soil, but others are fine with dry. Most prefer full sun, but some tolerate a bit of shade. Iris are among the earliest blooming plants in spring, but the tall Japanese water iris may not bloom until July. A few are American-born natives, but most are imports, with Central and East Asia figuring prominently as their homeland. Hard to get a handle on such a motley crew.
Iris reticulata, I. histrioides and their cultivars bloom very early. The elegant flowers stand about 6 inches above the ground and bloom in shades of purple, yellow and white. Long narrow leaves appear after the flowers but go dormant and wither around the time that hostas emerge, which makes them good for interplanting, says Tankersley. Native to Central Asia.
Another spring bloomer is crested iris (Iris cristata), which is native to woodlands in the eastern half of the United States. It grows from rhizomes and blooms in May with an elegant lavender-blue flower. Also around 8 inches high, it can be used as a perennial groundcover in shade or sun since it will spread. It won’t bloom reliably if it is in too much shade or gets covered with leaves.
The spring-blooming Juno types are perhaps not so familiar to amateur growers, but the group comprises up to 60 species. Boyce Tankersley, who grows several, says the plants resemble young corn and, at 12 inches tall, are good for rock gardens. They also grow from bulbs. One species often seen in the catalogs is Iris bucharica, named for Bukhara, a major ancient city in Central Asia. Another is I. aucherei, also native to the Caucasus.
You may also see Dutch iris listed in the catalogs. These are bulb-growing plants, about 15 inches high that go dormant in summer. They are hardy here but are not likely to return for more than five years.
When most of us hear the word iris, it is the tall bearded types that spring to mind. But they can be subdivided into six different groups, starting with the dwarf standard bearded iris that stand about a foot tall and bloom from April into May. They are often fragrant, especially the older varieties, and hybridizing them is not beyond the skills of amateur growers such as Virginia Winkler, member of the Northshore Iris & Daylily Society. Winkler has hybridized several iris, and one of her dwarf standard beardeds was formally introduced as ‘Golden Beryl’. It usually takes three years from cross pollination to first flower.
Kelly Norris, director of horticulture and education at the Greater Des Moines Botanical Garden, is a professional whose family breeds and sells iris at their rainbowfarms.net where they grow primarily bearded iris, Siberians, and some spurias (which bloom in mid-summer and can soar to 5 feet high.). Norris admits to a “childlike curiosity when it comes to iris. I love the colors, the vastness of the palette, the diversity and depths of the colors. Every plant geek has his home base.”
After the bearded types, it’s probably the sleek Siberian iris (Iris sibirica) that are most frequently grown here. They bloom in June and make excellent companions for peonies and early roses. They are moisture-loving perennials that form ever-expanding clumps as they mature and are readily divided.
Water Garden Iris
Siberians grow in regular garden soil but are particularly happy when planted on the shore of a pond garden. Several other iris species are even more insistent about preferring wet feet: Japanese water iris (I. ensata), Japanese iris (I. laevigata), yellow flag iris (I. pseudoacorus), blue flag iris (I. versicolor), southern blue flag iris (I. virginica), I. virginica var. shrevei and Louisiana iris (a group of five different species from the American South).
The question then becomes whether these water-loving iris can be grown in ordinary garden soil because some of them have extraordinarily beautiful flowers that many of us covet. Dan Kosta, horticulturist at Vern Goers Nursery in Hinsdale, has a Japanese iris that he grows in an 8-inch deep plastic-lined pit filled with acidic soils. He pierced some drainage holes in the plastic, and the plant is happy. He also grows a huge Iris laevigata ‘Colchester’ that lives in his pond. “It has dreams of world domination with the way it grows,” he says. Colchester’s flower is a remarkable mix of purple and white and well worth seeking out.
Boyce Tankersley has found that he can grow Japanese iris in alkaline soil if he keeps it moist, but his Louisiana iris petered out when he moved up here from downstate. Virginia Winkler, on the other hand, says she had “zero success” with Japanese iris, but grows two lovely Louisiana iris, the red ‘Ann Chowning’ and the deep deep purple “Black Gamecock’. She also reports that you can grow the infamously invasive yellow flag iris (I. pseudoacorus) out of water (which probably helps to keep it under control). Kelly Norris has friends who grow Louisiana iris in upstate New York.
So iris can grow where the books say they won’t and even 8 inches underground in downstate Illinois. The moral of the story? Try growing everything you fancy. You never know when you might be successful.
Editor Carolyn Ulrich has written for Chicagoland Gardening since its inception. She is a former weekly garden columnist for the Chicago Sun-Times and has received several awards for magazine writing from the Garden Writers Association. firstname.lastname@example.org