There are more than 300 species of irises from all the temperate regions of the world, including North America, and natural hybrids are common. Garden cultivars had appeared in Europe by the 16th century and followed settlers to the New World. A big boom in breeding came after 1830, and by 1939, the American Iris Society (AIS) counted more than 19,000 iris species and hybrids, with more introduced every year.
Most of these are bearded irises, with a complex ancestry that includes an early hybrid, Iris 5 germanica, as well as various European species. What makes them "bearded" is the fuzz (actually a landing pad for pollinating insects) on the falls, the three sepals that drape gracefully down beneath the "standards," the three petals that stand up. Newer cultivars are ever more ornate, with elaborate ruffles and intricate patterns of color all across the rainbow.
But not all gardeners share the taste for elaboration. They feel that the allure of the new has led to too many overwrought irises, often at the expense of fragrance and vigor. They are fascinated by older varieties—with simpler, cleaner lines and fewer frills, but usually more toughness and fragrance—that have fallen out of catalogs, surviving only in old gardens, cemeteries, and other out-of-the-way places.
So just as heirloom tomatoes were rescued by gardeners who love both their flavor and their stories, old irises have found champions. The Historic Iris Preservation Society, which is part of the AIS, is dedicated to preserving iris varieties, including bearded irises, that are more than 30 years old.
Gesine Lohr treasures an iris with blooms the rose-and-orange colors of an autumn sunset. In the 1930s, it grew in her grandmother's garden in New Jersey. Today, 'Indian Chief' lives on in pots in Lohr's garden in Alameda, California, and in the gardens of all those to whom she has passed it on. Lohr and other historic-iris devotees aim to save and identify as many as possible of the thousands of varieties that have come and almost gone since the 19th century.
These gardeners don't spend much time talking about iris care, because bearded irises, especially older varieties, are so easy to grow. They need full sun and well-drained soil that is amply enriched with organic matter such as compost. Mulch in cold winters and watering during dry spells can help, but old irises often thrive untended.
When clumps get large and crowded and flower less, which tends to happen every 3 to 5 years, irises are easy to divide. Just lift the cluster of rhizomes—swollen underground stems—with a garden fork, gently tease it into sections, and replant them. Or give some away. The only serious pest problem is iris borers, insect larvae that tunnel through the rhizomes. If you spot them, eradicate the infested plant, and plant different irises somewhere else in the garden.
Bearded irises are best planted in summer or fall, no later than six weeks before your area's first freeze. Situate the rhizomes just at the soil surface with the roots spread out underneath. "Like a duck," Lohr says. "Their feet are in the water but their back is above."
Irises "don't take much mollycoddling," says Boyce Tankersley, director of living plant documentation at the Chicago Botanic Garden in Glencoe, Illinois, who grows a number of historic varieties at home. "I don't spray them, I don't fertilize them any more than I fertilize anything else, and they keep coming back and giving me a good show."
Gardeners intrigued by the idea of growing sturdy, fragrant irises with interesting stories can start by visiting an iris garden in May, when bearded irises are in full, glorious bloom. One of the most spectacular is the Presby Memorial Iris Garden in Upper Montclair, New Jersey, where plants are arrayed by the decade in which the cultivars were introduced. A local chapter of the American Iris Society or the Historic Iris Preservation Society can point you to the right garden or grower.
Learn more about How to Grow Irises.