For Release On Or After 07/23/10
By Dan Gill
LSU AgCenter Horticulturist
We all are familiar with low-growing, running grasses like St. Augustine and centipede used to cover lawn areas, and in most gardeners’ minds, all other grasses are simply weeds. Ornamental grasses, however, are an often-overlooked group of herbaceous perennials that thrive in Louisiana and will grow beautifully with minimal effort.
The term ornamental grass is applied to grasses and grass-like plants that are used chiefly for their beauty. They are a large and complex group of plants with a wide range of growth habits and culture. In a strict sense, true grasses are members of the Poaceae or grass family. Many other plants that we think of as grasses are actually sedges and rushes, which belong to different families altogether. They, along with the true grasses, comprise the bulk of the plants we call ornamental grasses.
Many gardeners consider “ornamental grass” a contradiction in terms. To be honest, some of our worst garden weeds are grasses. Crabgrass, torpedo grass, wild Bermuda grass, nutsedge and Johnson grass are persistent, difficult-to-control pests many of us are all too familiar with. As a result, many gardeners are reluctant to purposefully plant grasses into flower beds or landscape borders.
Ornamental grasses, however, are truly attractive and not rampantly aggressive. But like their weedy cousins, they’re tough, resilient and susceptible to virtually no insect or disease problems. Ornamental grasses are an excellent choice for gardeners trying to create a landscape that is more self-reliant and requires less spraying, fertilization and maintenance.
The strong vertical or fountaining form of many ornamental grasses, combined with their feathery flower heads, makes a unique contribution to the landscape. The leaf blades add fine texture and colors, such as metallic blues, burgundy, white, creamy yellow and every shade of green imaginable. As grasses grow and seasons change, so does their appearance. The foliage may change color from spring to summer to fall. Grass foliage moves in breezes and catches the light like few other plants. Grasses also offer an impressive array of flower plumes and seed heads for interest at various times throughout the year.
Most ornamental grasses grow best in full to part sun, but they are tolerant of a wide range of growing conditions. If you plant them into an existing bed, you’ll need little soil improvement. Turn the soil and incorporate a 2-inch layer of organic matter in the area to be planted. Be careful to plant the ornamental grass at the same level it was growing in the container it came in and water it in well. These tough plants may be successfully planted this time of the year despite the heat. Water them thoroughly once or twice a week until they’re established, then just sit back and relax.
Some ornamental grasses are evergreen, but most go dormant for the winter. At some point before the end of February, cut the plants back to within a few inches of the ground. When you cut them back depends on whether you like the appearance of the dead foliage or not. Cutting back must, however, be done before fresh, new growth comes in spring
You can enjoy creating interesting combinations of ornamental grasses with other plants in your landscape. They’re easy to use in beds and borders, enriching neighboring plants with their presence. Try maiden grass varieties with bold-leafed tropicals like gingers, cannas or crinums. Pink pentas and blue daze make a good combination with purple fountain grass. The genus Muhlenbergia, commonly called muhly grasses, includes many attractive species excellent for landscape planting.
These rugged plants also can function as important structural features of the landscape. Tall grasses, such as pampas grass, vetiver, sugarcane and giant reed, can be used to divide the landscape into distinct spaces and are effective as hedges or screens.
An excellent reference on the subject is “Ornamental Grasses for the Southeast” by Peter Loewer, Cool Springs Press. This book contains an easy-to-use, A-to-Z format featuring most of the annual and perennial ornamental grass species available in the United States, all illustrated with color photographs. The book also contains chapters on bamboos, reeds, sedges and other plants that look like grasses.
Ornamental grasses are becoming increasingly available at local nurseries and garden centers. It’s time to get beyond lawn grasses and take a look at this other category of grassy plants. You’ll really appreciate what they can add to your landscape.
Rick Bogren