Some decorative grasses spell trouble, but attractive alternatives exist

  • Little bluestem is a drought-tolerant grass, with fine foliage. TNS

  • Even the straight species of prairie dropseed can find a place in many gardens, growing only 24 to 36 inches high and wide with a mound of fine-textured foliage that turns golden-orange in fall. Hoffman Nursery—TNS

Chicago Tribune
Thursday, April 20, 2017

In the realm of good-looking grasses, Miscanthus has long held a certain pride of place. In 1893, the cover of Gardening magazine, published in Chicago, featured a border of hardy grasses — variegated Japanese silver grass (Miscanthus sinensis ‘Variegatus’), zebra grass (Miscanthus sinensis ‘Zebrinus’), fountain grass (Pennisetum) and giant reed (Arundo donax).

These plants are still popular because their attractive seed heads are particularly beautiful in the winter. Several grasses can be used as ground covers, in mixed borders, as focal points, in containers and in prairie restorations. They add texture, color and movement to a landscape.

According to a study conducted at the Chicago Botanic Garden — findings were published in 2012 in the Journal of Environmental Horticulture — several types of the popular Miscanthus showed a significant potential to be invasive. As a result, the Botanic Garden is taking steps to remove all of the Miscanthus from its collections by the end of 2017. While the grasses may not pose a big problem in home gardens, the plants have invaded some natural areas in several states where they overrun native wildflowers and disturb habitats.

“We’re removing all of the Miscanthus because we don’t want to send a mixed message to visitors,” says Kayri Havens, the Botanic Garden’s director of plant science and conservation and senior scientist.

Landscape architect Craig Kruckenberg at Cantigny Gardens in Wheaton, Illinois, is also avoiding Miscanthus, which is not native to North America.

“I’ve been staying away from Miscanthus the last few years because people have been talking about how invasive they are,” he said. “We’ve made a conscious decision to get rid of them one at a time because there are better grasses that are native.”

You can prevent Miscanthus (and fountain grass) from seeding around the home garden by removing their seed heads in early fall, but then you’ll miss out on the winter interest they provide. One alternative to Miscanthus is native switchgrass (Panicum virgatum) with its tall stems, bluish leaves and delicate seed heads. Kevin McGowen, of Kaknes Landscape Supply in Naperville, is fond of switchgrass, especially the cultivar ‘Northwind.’ To showcase its upright habit, he planted eight of them in a perennial border and spaced them 6 feet apart.

“It can grow 6 to 7 feet tall and 2 to 3 feet wide, and it doesn’t flop,” McGowen said. He recommends pairing it with ‘Rozanne’ and ‘Jolly Bee’ geraniums and with garden phlox, saying “the bigger flowers look good with the grass foliage. I also like it with coneflowers — Echinacea ‘Magnus’ — the pink against the blue, or ‘White Swan,’ and also with Liatris or ‘Becky’ shasta daisy.”

Seven-foot-tall grasses may not be palatable for some; shorter native grasses may be more suitable in the home garden.

“They’re a lot more landscape-friendly,” said Melisa Bell of Montale Gardens in Wauconda, Illinois. “If the taller grasses aren’t used skillfully, they don’t look good. When it comes to grasses, it’s all about scale and good design principles. I always go back to the purpose — is it to screen or to bring attention? Keep in mind the use.”

Bell favors ‘Carousel’ bluestem (Schizachyrium scoparium ‘Carousel’). “This one has a cool form — it’s a bowl shape. It’s fuller and rounder than other bluestems, and it looks great all season.” She cautioned that bluestem doesn’t tolerate shade, high fertility or a lot of water. “Give it full sun and mediocre soil, and it will do great. And the fall color is amazing, from coppery-pink to mahogany — really cool.” She pairs it with autumn-flowering blue asters, ‘Montrose White’ calamint and ‘Pica Bella’ coneflower.

Richard Hawke, on the other hand, is partial to prairie dropseed (Sporobolus heterolepis). The plant evaluation manager and associate scientist at the Chicago Botanic Garden appreciates the plant’s fine-textured leaves, longevity and drought tolerance.

“I think it’s one of my favorites, whether it’s the straight species or the cultivar, ‘Tara.’ They’re both beautiful plants.” For plant partners, Hawke suggests pairing prairie dropseed with goldenrods, geraniums and asters — such as ‘Snow Flurry’ aster — or simply planting the grass in large swaths. “A big bed of ‘Tara’ is so structural, more so than a lot of grasses.”

And then there’s lovegrass. Heather Prince, nursery manager at Wannemaker’s Home and Garden in Downers Grove, prefers the native purple lovegrass (Eragrostis spectabilis) for the front of a full-sun border.

“It’s short, like a mini-tumbleweed, but when it flowers, it’s a clump,” Prince said. “It has really nice reddish fall color and flowers like baby’s breath.”

At 1 to 2 feet tall and wide, lovegrass grows in average, dry to medium, well-drained soils and tolerates drought once established.

Grasses need not grow alone. There are several sun-loving perennial partners for them. Prince suggested pairing any of the grasses above with purple coneflower, black-eyed Susans, wild bergamot, slender mountain mint, wild quinine, blazing stars and milkweeds.