There’s an ornamental grass to fit nearly every landscape application, but how do you choose? Here’s a list of hardy selections from our neighbor to the North.
Why are ornamental grasses so special? The reasons are as numerous as the grasses themselves. Once established, many varieties are drought-tolerant and resistant to threats from deer and other pests. Some forms lend architectural interest to the landscape, while others serve to “soften” large-scale projects. Many provide four seasons of interest; some display their best ornamental characteristics in fall, when gardens are fading from glory. Grasses provide sound and movement, offering a sensory treat other plants cannot match.
At Bluestem Nursery in Christina Lake, British Columbia, we specialize in growing grasses and willows. We’re located north of Spokane, just over the Washington border in a Zone 4(5) region that experiences hot and dry summers. It’s good for grasses, but the varieties we produce do well in a broad range of conditions.
This year we produced 122 varieties of ornamental grass, so it’s no easy task to select only a few to recommend. That being said, here are five that are worthy of just about any well-dressed landscape.
Gray’s sedge is a North American native that’s not common in the trade, but it’s well-worth growing because of its unusual flowers. The spiky growths look like the morning star, a forbidding medieval weapon, but this dramatic feature is what makes this selection stand out. The flowers can be dried to add to floral arrangements to make a real statement.
Foliage is light green (deeper green in shade); blades are about 3/8-inch wide and 12 to 40 inches long. The showy flowers bloom from May through June, starting out green and turning a chocolate-brown. Stalks reach 16 to 48 inches in height.
Full sun to light shade is ideal; if planted in full sun, however, this sedge requires moist soil to look healthy and lush. Established plants are drought-tolerant, except during prolonged dry periods.
Carex grayi is a cool-season grass, hardy to Zone 2. It’s one of my favorites; very durable, too.
Deschampsia cespitosa ‘Goldtau’
Deschampsia cespitosa ‘Goldtau’
This cool-season, clump-forming tufted hair grass is a smaller, more compact version of the species, virtually all of which are highly ornamental. With its dark green leaves and golden inflorescence, however, ‘Goldtau’ really stands out. From Europe, it’s used in a lot of high-end landscaping, and it’s becoming more popular in North America. And when used in great numbers, such as massed along a driveway or walkway, ‘Goldtau’ makes a real impact.
Foliage is very narrow, reaching from 12 to 24 inches tall. The flowers, which emerge in June through July, are golden yellow and reach a height of 16 to 24 inches. Ideal conditions for Deschampsia cespitosa ‘Goldtau’ include full sun to light shade and moist, fertile soil (although average soil is sufficient); hot, dry conditions are tolerated if ample water is supplied.
This outstanding tufted hair grass is a cool-season selection, hardy in Zones 3 to 8. Bluestem used to grow several Deschampsia, but we’ve narrowed our selection down to a few favorites. In fact, this selection would be our choice for the Perennial Plant Association’s perennial plant of the year.
One of the best selections for dry shade, greater wood rush will self-sow and eventually form a luxurious, weed-proof groundcover. It’s truly a foliage plant, with bright green leaves whose ½-inch-wide blades reach 12 to 16 inches in height. Some gardeners remove the flowering stems, believing they detract from the clean foliage. (Flowering occurs from May through July.) However, if seed heads are not removed, self-sowing is encouraged and a true groundcover mat can be achieved.
Cool or warm?
Ornamental grasses generally are classified as “cool season” or “warm season” – but what does that really mean? It’s all in when they start to grow.
Cool-season grasses begin their spring growth as soon as the temperature rises above freezing; this is the time when foliage is at its most brilliant. Flowering starts by early summer when overall growth begins to slow. It’s important not to transplant cool-season grasses during the hot summer months when their roots are not growing. They transplant well, however, in spring and fall.
Warm-season grasses begin to grow later in spring; be patient and you’ll be rewarded with mid- to late-summer flowering, which often continues until frost. Be careful not to transplant these selections until signs of growth are evident; warm-season grasses require warm soil temperatures for a couple of weeks before they stretch their leaves, and disturbing their roots when the soil is cold will only lead to disappointment.
Luzula is very much at home in a woodland setting, and it combines well with other shade-loving perennials, such as Epimedium and Bergenia, as well as with ferns.
This hardy, Zone 3 rush can grow under the shade of large trees, preferring part to full shade and moist, fertile, acid soil. The evergreen foliage keeps its rich color through the winter, although leaves can get nipped by extremely cold temperatures.
Panicum virgatum ‘Shenandoah’
Panicum virgatum ‘Shenandoah’
With its dramatic color, Panicum virgatum ‘Shenandoah’ (‘Shenandoah’ switchgrass) often is mistaken for Japan-ese blood grass. The leaf tips emerge green, but turn red soon after the foliage starts to grow in the spring, and in fall the color turns a spectacular, deep burgundy.
A warm-season selection, ‘Shenandoah’ has proved to be a popular switchgrass because the foliage emerges green, then turns red during the growing season, highlighting the plant’s cascading form. Half-inch-wide blades reach 40 to 48 inches, and the flowers, which are tinged with pink, stand above at 50 to 60 inches.
Switchgrass prefers full sun and moist, fertile soil, but it can adapt to a wide range of soil types. It is hardy to Zone 4.
Blue-green moor grass is a tough plant, tolerating some of the most challenging conditions. It’s a clump-forming, cool-season selection with foliage that appears gray-blue on the surface and green underneath; medium-wide blades grow 12 to 16 inches in height. Impressive, jet black blossoms bloom about the same time as daffodils, on stalks that can reach 20 to 24 inches.
Ideal conditions include well-drained soil and full sun to part shade. Although it’s quite tolerant of heat and drought, the plant does best in light shade and with a bit of supplemental watering in very dry climates.
Hardy to Zone 4, Sesleria heufleriana can be considered semi-evergreen; it tries to maintain its unique, bicolored foliage throughout the winter.
Jim Brockmeyer is owner of Bluestem Nursery, a small, specialized operation in Christina Lake, British Columbia, just across the Washington border. Established in 1994, the nursery offers exceptional ornamental grasses and willows to wholesale and retail customers. Brockmeyer can be reached at firstname.lastname@example.org. Sally Benson is the editorial director of American Nurseryman; she can be reached at email@example.com.