Mention the word “grass” and most people still imagine expanses of shorn Kentucky bluegrass, the staple of iconic American lawns.
Ornamental grasses, however, boast a lot more pizzazz than typical turf, and their appeal lasts long after retiring the lawn mower for the season.
And on the high plains, grasses make sense in Front Range gardens. Except, perhaps, to some wary senior citizens who grew up on the prairie.
“I get some old-timers who look at me like I’m crazy, trying to get people interested in grasses when they’ve spent a good share of their lives trying to eradicate them,” said Kelly Grummons, co-owner of and chief horticulturist at Timberline Gardens in Arvada. “For them, it’s a tough sell, but the younger generations are more interested.”
Ornamental grasses run long on interest. Both annual and perennial, cool- and warm-season, they come in a wide range of heights, textures and colors ranging from blue to blond, silver to purple, red to variegated greens. Some are upright; others flop into fountain shapes or form tufts. Most of these grasses need to be cut only once a year – in spring – to encourage new growth. Every few years, perennial ornamental grasses benefit from division. When the center appears less than lush, dig up the clump, cut it into sections and replant as you would any other perennial.
Randy Randolph, the founder of Lifescape Associates Inc., a Denver landscaping firm, uses a variety of ornamental grasses. A landscape architect, he gravitates to grasses for their shape, texture and ability to hold light and add movement to gardens or containers.
“And just when the whole garden is tired, grasses are in their prime,” Randolph said.
At their peak, many ornamental grasses sport showy flowers. Set on long stems or pendants, the flowers resemble fox tails, feathery plumes or wheat. They shimmer and sway gracefully in the slightest breeze, animating the landscape and providing fetching foils for surrounding plants. Many grasses change color dramatically in autumn; and if left alone, they lend interest to an otherwise barren winter landscape. Catch sight of a grass’ delicate flowers encrusted in frost, and you’ll be a fan forever.
The spring edition of the catalog from High Country Gardens, a Sante Fe-based company specializing in plants for the American West, announced Silver Spike Grass (Achnatherum calamagrostis) as its 2006 Plant of the Year. The summer bloomer relishes our high altitude, low humidity and cool nights. A European native, the grass seeds made their way to High Country Gardens via Colorado’s own Lauren Springer Ogden, who has cultivated Silver Spike for more than eight years and pioneered it as the new gold standard for grass.
As Mile High gardeners face low-water realities, Grummons moves away from more common, more thirsty miscanthus and toward more drought-tolerant varieties. Last year, Timberline introduced Sporbolus Wrightii. He also likes Los Lunas, an exotic grass selected by the Department of Agriculture as a large, showy windbreak in areas where other plant material refused to grow.
“It’s lovely in the garden and quite drought-tolerant,” said Grummons. A number of ornamental grasses become more drought-tolerant as they mature and send their roots deeper into the earth.
For a bit of bronze, Grummons turns to Carex Buchananii. A vertical sedge with distinctly peachy tones, this plant requires substantial moisture and will tolerate part shade or sun. Grummons particularly likes mixing this russet sedge with apricot-colored verbena.
Another option is Nesella tenuissima. Also known as ponytail grass or Mexican feather grass, Grummons has spotted this survivor thriving even when neglected in scorching parking lots.
“It’s a wonderful tall grass and when established after several years becomes quite drought tolerant, but it’s definitely too coarse and tall for containers,” he said. Colorado PlantTalk endorses several grasses, including northern sea oats – a short, showy, shade grass with bamboo-like foliage and grain-like flowers. Also touted is ravenna grass or plume grass, a good substitute for the behemoth pampas grass; and giant Chinese silver grass, which can lend a tropical touch to sizable plots that call for plants with a grand scale.
Randolph warns against ribbon grass. Grummons waves a red flag when Blue Lyme grass comes up. Both are extremely aggressive. The plants send out underground runners known as stolons.
“Blue Lyme grass is beautiful, but it spreads out several feet at a leap. It’s fine to use in a little planting bed, but if you mix it with other plants, it will penetrate and make a mess,” says Grummons.
He noted that a number of the grasses native to Colorado are stoloniferous, so the prairie denizens must be planted with care lest they usurp the landscape: “That’s how the prairie turf was formed,” Grummons says.
He offers the following tips for cultivating ornamental grasses:
Don’t plant grasses in fall. Get them in the ground by midsummer. If you can’t resist a grass on a nursery’s autumn clearance sale, mulch it and water through the fall and winter.
Deep soil preparation helps roots get established and allows grasses to grow more drought tolerant as they mature.
Feed grasses in the fall. Grummons advises using a high-nitrogen fertilizer, manure or his preferred product: Alpha One, an alfalfa-based plant food.
For optimum performance, he also urges the use of myccorhizae – a beneficial fungi that when applied to roots, protects plants from pathogens and allows them to better assimilate water and nutrients.
Grummons advocates clump-forming grasses, but warns against invasive stoloniferous species unless used in a contained area without other plants that will get strangled by the sort of grassroots effort that gives the phrase its well-deserved reputation.
High Country Gardens’ catalog offers this ornamental-grass design advice: For drama, plant grasses in groups of three or five. “Avoid the lonely species.” Mix grasses, contrasting size, shape and color. “Be brave and experiment.”
Given their ease of cultivation, their durability and their many admirable traits, there seems just one more piece of advice: Don’t stay off the grass – at least not the ornamental kind. Who knows? Maybe a blade of fescue or pennisetum inspired Walt Whitman to write, “I believe a leaf of grass is no less than the journey-work of the stars.”
