Master Gardener: Ornamental grasses for low-maintenance gardens
As summer flowers fade and the leaves turn fall colors in Minnesota, many varieties of ornamental grasses are at their majestic peak and in full flower. They stand from 3 feet to as much as 12 feet in height (although some are shorter), as vibrant kings of the perennial garden with their jaunty, yet graceful looks. Ornamental grasses have not only become key components in the driving trend toward sustainable and low-maintenance landscapes, but their strong vertical lines offer living sculpture in today’s native gardening mix.
“Today there’s a real interest in native grasses and using native cultivars in the garden,” said Mary Meyer, the University of Minnesota Extension professor and educator who maintains the only collection of ornamental grasses accredited by the American Public Garden Association in the U.S. “We went from having exotics from the non-natives and huge numbers of Miscanthus [in the collection] to more and more North American native species. And really the grasses that are native in the prairie.”
Meyer’s ornamental grass collection of around 175 varieties at the Minnesota Landscape Arboretum in Chaska, Minnesota marked its 30th anniversary last fall. “There has been a big change in people’s acceptance of grasses,” Meyer said. The woman who is now known as the “grass lady,” was a graduate student in 1987 when she proposed planting as many varieties as she could get her hands on for scientific observation, even though her professors were skeptical.
“When I came to Minnesota, everyone said, ‘we can’t grow any of those — it’s just too cold here,'” Meyer recalled. “But no one had really tried it. Everyone was just assuming it was too cold for any grasses to live.” But Meyer persisted, first winning over Professor Harold Pellett who agreed to provide the funding to help her start a trial collection and then Arboretum Director Peter Olin, who provided “an orphan garden area” for 100 varieties.
However, she says she knew much more work had to be done to win over the public, who couldn’t imagine adding the wild-looking plant they saw growing on the roadside into their gardens. “When my mother-in-law saw the grass collection at the Arboretum, she looked around and said to me, ‘Mary, I can’t understand why you don’t get rid of all these weeds,'” Meyer said. “But she was the public speaking. It wasn’t until we really got the distinct forms, the cultivars or the nativars — the ones that look consistently good — that people could really see that they had potential.”
A couple of very hardy invasive grasses like ribbon grass also gave the plants the reputation “that they were going to take over,” she said. “The concept of a bunch grass — a grass that sits in a bunch like a peony was difficult for people to understand.”
By the early nineties, Meyer was able to give some interested Minnesota growers a list of the ten best hardy grasses, based on her plant trials. Meyer remembers the first example of grasses used in a landscape design she’d ever seen in the State, right on the University’s Minneapolis campus next to Northrup Auditorium. It was created by Oehme van Sweden, a landscape design firm that got a lot of attention in the 1980s by including grasses in their public installations on the east coast. “I could point to that and say, ‘this is a wonderful example of the new American design for landscaping,'” she said. Growers in Minnesota began to sell them for the first time.
Today, ornamental grasses are widely planted in public settings and used as green infrastructure in bioswales and green roofs. Consumers can find many kinds of grasses in garden centers, including an upright selection of native little bluestem patented by the University in 2006 called Blue Heaven™. “In the beginning, everyone thought you had to put them in a grass garden, all by themselves somewhere,” Meyer said. “The idea of just planting them with other perennials, with other shrubs just like you do other plants was kind of a difficult concept.”
Anyone who has ventured to add an ornamental grass to their landscape knows these plants are extremely low-maintenance. Meyer says they only require watering to establish them in the first year after planting. Ornamental grasses don’t need fertilizer, and other than cutting them down to the ground every year in the early spring, the plants thrive on their own.
“People are interested in natives and lower maintenance, conservation of resources,” Meyer said. “Grasses work for all of those.” Researchers at the University of Minnesota are also studying grasses as a source of food for Lepidoptera, particularly the skipper butterfly, in their effort to understand grasses as part of a whole eco-system.
By planting ornamental grasses, Meyer says gardeners can make a big difference to the environment. “We think that there’s a lot of scientific information showing backyard gardens can contribute to the diversity of species, making corridors between parks and preservation areas,” she said.
Today Meyer continues her scientific research, evaluating new varieties. The Arboretum’s grass collection also acts as a display for educational purposes for both gardeners and the industry, as well as a national reference collection.
As she looks back at three decades of research, Meyer says, “it’s been very fulfilling that it’s made a difference to people and growers in Minnesota.”