Ornamental Grasses With a Different Accent

By Adrian Higgins
Thursday, October 25, 2007

Chalk up one good thing to the drought: this year's performance of the flame grass.

This variety of miscanthus (Purpurascens) gets its common name from the fact that in October it undergoes a rapid metamorphosis after the showy seed heads ripen and whiten. The foliage shifts from green to various shades of orange and tan before darkening to a coppery hue. Planted in a mass, flame grass grabs the eye, and not just for its foliage. It is the right height for smaller gardens, growing to about five feet, and it provides a vertical line that is not stiff. I admire it most at dusk, when its burnished foliage glows against a bank of nandinas.

In normal years, its autumn performance is marred by the fact that late-summer rains and storms flatten the stalks. Efforts to prop up the grass (with a circle of string at two feet high) produce something absurdly gathered and unnatural.

Tom Mannion, a landscape designer in Arlington, said he has given up on them, and you can't blame him.

Indeed, 20 years after the ornamental-grass revolution swept through this country, we are learning to discard now-established varieties such as flame grass (and Red Baron Japanese blood grass, never as red as billed in our hot climate and potentially invasive in the wild) and move on to others that are better garden plants.

The continued interest has led to a collection of established and novel varieties that add much to gardens of every size, setting and style. Grasses lend a natural air to the garden, and they are ornamental in summer, fall and winter, which is no mean feat. They are little bothered by disease and pests and require no nasty chemicals. Grasses are resistant to deer feeding. Most of all, they provide both fine textures and strong lines in plant compositions.

Like any plant, they shine most when used with a clear purpose in mind. I like them as an accent in a border of other plants, especially if repeated at the periphery of one's view, to create visual echoes. If you are massing them, do so with gusto. I love to see a strong line of switch grasses forming a horizontal brush stroke in the distance of a framed view. Growing to five or six feet every year and then stopping, the switch grasses are predictable screens that won't outgrow their space, unlike a row of evergreens.

Some of the switch grass varieties are fabulous. Heavy Metal is an old one but still a sterling performer, producing ethereal sprays of seed heads above the upright foliage.

Cloud Nine grows taller, to eight feet, and a similar tall variety named North Wind is perhaps a better bet against storm flopping. Shenandoah, a shorter version, is valued for its small-garden stature and its distinct maroon-red fall coloration. The variety Dallas Blues, which came on the market fairly recently, is one of the prettiest of all ornamental grasses, with large inflorescences that turn an astonishing lavender-violet in late summer. The problem is that it collapses, particularly with any degree of shade or soil richness, and is impossible to right. I have even tried elaborate hooped stakes set early in the season for the foliage to grow through. Still it flops.

The switch grass is native to the American prairie, and it is not the only indigenous grass that works well in the garden, especially when used with abandon on large sites. Little bluestem, which can grow to four feet despite its name, has a blue cast in summer, turning in fall and winter to a ruddy orange. These wisps are especially beautiful in a hilly meadow that catches the sideways sunlight.

I recently saw such a terrain in Pennsylvania, but planted entirely with prairie dropseed grass, forming a mesmerizing series of swirling green clumps.

Mannion, the Arlington landscape designer, said he uses prairie dropseed as a key ingredient for meadows in deer territory. "It's just a great mass ground cover," he said. He interplants it with daffodils, star of Persia ( Allium cristophii) and ornamental poppies, all of which give sequential ornament in the spring, the dead season for grasses. Of course, you don't have to be afflicted with deer to try that combination.

Pink muhly grass is named for its mauve-pink inflorescences, which never look as colorful in the garden as in a photograph but are impressive nevertheless. The grass is hardy here if given a protected site and good winter drainage. Mannion said he has never had the courage to use it in a client's garden because he has seen stands of it look great for the first year but then flag.

I feel the same way about Mexican feather grass, whose short, wispy clumps look fabulous when green, but then the blades turn brown. Just as you are ready to yank it out, it turns green again. I think excellent winter drainage is the key to success with this grass. It was still looking great when I saw it at Brookside Gardens in Wheaton last week.

A feathery perennial called bluestar ( Amsonia hubrectii) makes a great companion planting for grasses because it looks like one, especially in the fall, when it turns from green to golden yellow.

Miscanthus grasses have a way of growing tall and capturing the backlit sun in a magical fashion, but their root clumps are virtually impossible to lift by hand once broad and deep. The daintier variety Adagio grows to about five or six feet and fits more easily in a smaller setting. While some miscanthus varieties have yet to flower, Adagio has been blooming for weeks.

"It has a distinct golden tinge and [is] compact in nature," said Mannion, like me a huge fan of this grass. He uses Adagio and other grasses with landscape roses, and the pairing is foolproof. He likes to use Knock Out and the various Meidiland ever-blooming varieties.

In shade conditions, where the hakone grasses excel, Mannion likes to use the native wild oats. Not a novel grass, it is nevertheless handsome with its flattened seed heads, arching stems and capacity to seed and fill in a space.

The years have not been kind to the fountain grass. I find it dull and wan. A popular variety named Moudry self-seeds in places you don't want it, including the lawn. I much prefer a related species, Pennisetum orientale, whose flower heads are more slender and attractive, appear as early as June and don't self-seed aggressively. I grow the variety Karly Rose, whose inflorescences have a mauve tinge.

The feather reed grass Karl Foerster has been around since the early days, but it remains a tremendous player in the modern garden. Its slender golden plumes stand spearlike on wiry stems that refuse to bend or break.

A related grass, the Korean feather reed grass, is deserving of more use. It forms a broader plant with larger flower heads that arch pleasingly. Rick Darke, an ornamental grass expert and author, refers to it as "attractively lax in growth" and an "excellent container subject."

Ornamental grasses generally are planted in the spring, when they show up with increasing variety and anticipation at the local garden center. Scout your terrain now for suitable sites.

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