Ornamental grasses add movement to gardens

By Ted Schaaf
Gardens on Spring Creek

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We along the Front Range of Colorado should all embrace the use of ornamental grasses in our landscapes. After all, our native environment is a shortgrass prairie. A short trip outside the city limits, where irrigation is lacking, brings home this fact.

Often we overlook these beautiful plants at nurseries because they're not overly attractive in their pots. Since springtime is when most of us buy plants, we lean toward spring blooming plants that are already showing color. Grasses, on the other hand, can give us a full four seasons worth of interest, something that not many perennials can boast about.

Graceful grasses

One of my all time favorites is the Blue Avena grass (Helictotrichon sempervirens). Native to the rocky hillsides of France and Italy, this grass is one of the best for architectural interest. Leaves of Blue Avena are a striking, steel blue color. By early summer, 6-inch silver blue panicles rise above the foliage, dancing with the slightest breeze. Blue Avena can be grown in part shade if not overwatered. Moderate watering will allow this plant to reach its full potential. Come spring, it's best not to prune this plant back as you do with most grasses. Instead, wait until you see new growth, then comb out the dead foliage with a leaf rake. After three years, divide the clumps using a sharp shovel.

A must-have grass is Little Blue Stem (Andropogon scoparius). It's a native pasture grass found in all of the contiguous 48 states. Little Blue Stem is a warm-season grass that is hardy to zone 3. It is very drought tolerant after establishment. Thanks to plant hybrids, the green industry has propagated two cultivars that are true to their names. 'Blaze' is a green variety, turning a beautiful red fall color and holding interest well into the winter. 'The Blues' was selected for its blue-colored foliage. Although not as showy as 'Blaze,' its fall color is a rich orangey wheat color. Both grasses have wonderful fuzzy seed heads that sparkle when backlit by the afternoon sun. Little Blue Stem is a great xeric plant and should be on everyone's plant palette.

Although it's only an annual in Colorado, Purple Fountain grass (Pennesetum setaceum 'Rubrum') is outstanding. I often use it in my annual designs. It's a great accent for garden borders. Native to Africa, its bronze foliage is topped by 14 inches of reddish purple flower plumes. Children love to play with the feather-like plumes. Last year a new cultivar called 'Fireworks' was introduced. Similar in all other respects to its cousin, 'Fireworks' has bright red leaves. It's striking when massed with zinnias, especially the bicolor Starlight Rose. Purple Fountain grasses are at their best when grown in full sun and with moderate moisture. Divisions of this grass, taken in the fall, can be potted and overwintered indoors.

By far, the best grass for its architectural interest is the Northern Pampas grass (Erianthus ravennae). It's a hardy grass that will survive to zone 4. Early in the season this very large, warm-season grass is wider than it is tall. In late summer, incredibly long flower stalks shoot up into the air reaching over 12 feet. Older plants can have as many as forty flower stalks. This grass can be useful as a backdrop or as a privacy screen. Hardy Pampas grass does well when given full sun and moderate moisture. At the Gardens on Spring Creek, we use Hardy Papas grass as a winter specimen. It's an outstanding accent, especially during the holidays when we highlight it with red spotlights.

Companions

Most grasses are at their peak in summer, so perennial flowers that bloom in the late summer or fall will highlight them well. Some of my favorites are Black Eyed Susans, Prairie Coneflowers, Goldenrods, Blanket Flowers, Yarrow, Gay Feather and Coreopsis.

Most of the silver foliage plants that make up the genus Artemisia are especially striking when they are paired with ornamental grasses. And don't rule out roses. One I especially like is the Red Leaf Rose. Its striking foliage remains attractive well after the flowers are gone. Red rose hips are an added bonus to this plant. Give this rose room to grow, as it can reach 6 feet in height with a 6-foot spread. Some pruning, after it flowers, can be used to control its growth.

Happy gardening!

Ted Schaaf is the horticulturist for the city's Gardens on Spring Creek, located off Centre Avenue about one-half mile south of Prospect Road in Fort Collins.