Siberian Iris and Other Beardless Irises for the Garden

Text by Caleb Melchior for the March/April 2018 issue of Horticulture.

Beardless iris are diversely colorful flowers, and they’re good garden plants that play well with others. They’re also easier to grow and design with than bearded iris. I talked with several experts to learn about iris from the Siberian, spuria and crested classes. Plan to plant them in spring or late summer into early fall.

Siberian iris
I can hear the smile in Jan Sack’s voice: “We came around the corner of the house; she had half an acre of Siberian iris in full bloom. From that moment, we thought, that’s what we want in our own garden.” She’s describing the 1982 visit to Bee Warburton’s garden that started her and her husband, Marty Schafer, off on their adventure with irises. Today they’re known for their colorful introductions and their mail-order nursery, Joe Pye Weed’s Garden, which focuses on beardless iris.

“At that time, the only colors available were white, blue violet, a yucky wine color and a brand-new pale yellow,” Sacks says of their early days. But they saw the promise in these plants and started hybridizing. Their current listing contains an astonishing array of Siberian iris (Iris siberica), from glowing yellow ‘Kiss the Girl’ to ‘Purring Tiger’, with golden falls netted in purple. “After 25 years, we have some really great new colors,” Sacks says. “Bright yellows, brighter blends and warm browns moving toward orange.”

Color isn’t the only thing that draws them to Siberians. “We come from a gardener’s perspective,” she says. Siberian iris derive from two species: one squat and barrel shape, the other holding flowers aloft. This difference results in pleasing variations within Siberian cultivars. “Some people like a shorter mass of bloom,” Sacks explains. “Others like the flowers sparkling above the foliage.” The diversity extends to flower size. “There’s no classification limit on the size of the flowers,” she says. “They range in size from two inches across to five inches across. Marty and I love them all.”

Once they’re settled in the garden, Siberian iris are easy to take care of—in fact, Sacks says that “the hardest part about growing Siberians is getting them established.” Don’t treat these like bearded iris. You can’t just chuck them in the ground and expect them to root. “You have to keep them moist while they’re settling in, attaching [their roots] and growing,” she explains. Thereafter, sunshine and a bit of attention—that’s all they need. Settle in and enjoy the flower show.

Spuria iris
So you’ve got your dancing butterfly flowers with the Siberians. What else do you need? How about a phenomenal cutting flower with narrow, jewel-tone flowers? Jim Hedgecock of Comanche Acres Iris Farm, just north of Kansas City, Mo., is an Iris spuria evangelist. “They’re a fantastic cut flower,” he says. “You can cut them in tight bud and keep them in cold storage for up to three or four weeks.” What florist—professional or hobbyist—could resist the navy ‘Mythical Nights’ or clear blue ‘Catalina Bay’ (both Hedgecock introductions)?

How to decide which spurias to try? Hedgecock recommends starting with lower-priced varieties. “We [mail-order companies] work by supply and demand. If a variety doesn’t cost much, there’s a reason for that,” he explains. “It’s a good grower and we have a lot of it.”
Having chosen your spuria varieties, it’s essential to think about their place in the garden. They have a strong foliar presence. Their foliage “is like a cattail, with long leaves standing straight up, two-and-a-quarter to four feet high,” Hedgecock says. Unlike many commonly grown iris, spurias senesce in summer. “By August, their foliage will go brown,” he points out. “They put out new foliage in the fall that matures in the spring.” You might be tempted to fill the gap they leave with vigorous summer companions. Don’t. “You don’t want dahlias or something similar crowding out the new growth when it sprouts in the fall.”

If you’ve grown a tall bearded iris, you know how to cultivate spurias: lots of sun, plenty of space and good drainage. Hedgecock recommends keeping a foot of dry soil without mulch or encroaching perennials around the base of each plant. Spurias are sensitive to overwatering when they’re summer dormant, so make sure that they’re in a well-drained location with companion plantings that thrive in similar conditions.

Spurias have two points of difference in care to tall bearded iris. First, their roots can’t dry out in transport, or they’ll die. As with Siberian iris, it’s important to keep the roots moist. Carefully watch over the plants as they’re getting established. Secondly, they resent frequent disturbance. Once established, a clump of spurias can go 10 to 15 years before beginning to decline. Hedgecock recommends spacing them at three feet on center at a minimum. “It’ll look really spare at first,” he says, “but they’ll be healthier in the long term.” You’ll have butterfly blooms for years on end.

Crested iris
“People often say to me, ‘I want to grow iris, but all I have is shade,’” Jan Sacks reports—and she has a solution. Crested iris (I. cristata) happily grows in shade. It’s a diminutive woodland species that occurs throughout the central United States. “Iris cristata is not native to New England, but it behaves like it should be,” says Sacks, who lives in Carlisle, Mass. “It’s very happy here.” I’ve seen it growing joyfully on dry ridges in Arkansas and thriving in shady New York gardens.

Crested iris grows as a mat of upright leaf fans, 6 to 8 inches high by 24 to 30 inches wide. In mid-spring the crowns erupt with blue, lavender and white flowers. Sacks and Schafer curate wild-collected forms from Sam Norris and Darrell Probst and cultivated hybrids from regional experts. Sacks says that the neatest part of the flower is the crest, at the top of the falls, which often has dramatic markings in yellow, blue and white.

These plants are easy to grow. Partial shade and good drainage, with a light layer of leaf mulch, will result in the happiest crested iris. Like other beardless iris, their roots need to be kept hydrated during transplanting. They’re highly drought tolerant once established.
If you don’t have the attention to bestow on a specialist collection of tall bearded iris, open your garden to these phenomenal beardless varieties. Thank the experts devoting their attention to these wonderful Siberians, spurias, and crested varieties. Plant a few of these experts’ favorites and prepare for a kaleidoscope spring.

Image credit: Nadanka/iStock/Getty Images