Fireworks fountain grass. (Photo by Dan Gill, LSU AgCenter)

Miscanthus. (Photo by Dan Gill, LSU AgCenter)

Pennisetum. (Photo by Dan Gill, LSU AgCenter)

For Release On 07/17/15

By Dan Gill
LSU AgCenter Horticulturist

Ornamental grasses are an often-overlooked group of herbaceous perennials that thrive here and will add beauty to your landscape with minimum effort. This versatile group of plants is becoming increasing popular. Gardeners planting ornamental grasses are discovering that their variety of sizes, shapes and colors can add texture, motion and grace to the landscape.

What they are

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 we think of as grasses are actually sedges and rushes, which belong to different families altogether. Along with the true grasses they comprise the bulk of the plants we call ornamental grasses.

Some gardeners are concerned about planting grasses into ornamental beds. To be honest, some of our worst garden weeds are grasses. Crabgrass, torpedograss, wild bermudagrass and Johnsongrass are persistent, difficult-to-control pests with which most of us are all too familiar.

As a result, gardeners may be reluctant to purposefully plant grasses into flower beds or borders in their landscape. Ornamental grasses, however, are not rampantly aggressive and are truly attractive.

The strong vertical or fountain form of many ornamental grasses combined with their feathery flower heads make a unique contribution to the landscape. Grass foliage moves in the slightest breezes and catches the light like few other plants. It adds 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. Grasses also offer an impressive array of flower plumes and seed heads for interest at various times throughout the year.

Easy care

Like their weedy cousins, ornamental grasses are tough and susceptible to virtually no insect or disease problems. They are an excellent choice for gardeners trying to create a landscape that is more self-reliant, requiring less spraying, fertilization and maintenance. As a group, ornamental grasses are remarkably drought tolerant, and after they get established rarely need supplemental irrigation. They do not, however, mind in the least the frequent rainfall that often occurs in mid-to-late summer.

Most ornamental grasses grow best in full to part sun, but they are tolerant of a wide range of growing conditions. Several, including inland sea oats (Chasmanthium latifolium), Japanese sedge (Carex morrowii) and hair grass (Deschampsia caespitosa), like shade.

If you are planting into an existing bed, little improvement will be needed before planting grasses. In areas previously unplanted, turn the soil and then incorporate a 2-inch layer of organic matter.

Be careful to plant the ornamental grass at the same level it was growing in the container, then water it in well. These tough plants may be successfully planted this time of year despite the heat. Water them thoroughly once or twice a week until they are established, then just sit back and relax.

Some ornamental grasses are evergreen, but most go dormant for the winter. By the end of February, cut the plants back to within a few inches of the ground. Powered hedge trimmers or string trimmers work well for this task.

The timing of when you cut ornamental grasses back during winter depends on whether you like the appearance of the dead foliage or not. You may cut them back as soon as they turn tan. But I like the form and appearance of the dormant grass and leave them as is through the winter. Cutting back must, however, be done before the fresh, new growth comes up in spring. You may fertilize ornamental grasses in April.

The overwhelming majority of ornamental grasses do not “run,” but the clump they form will become larger each year. If you decide a clump is growing too large for the area where it is planted, or if you simply want to propagate a grass you particularly like, you may divide the clump and replant the separate parts.

After you cut the clump back in late winter or early spring, dig it up, getting as much of the root system as possible. Then, use a large sharp knife or a pruning saw to cut the clump into two or more pieces. Plant one division back in the original location, and plant the rest in other areas of the landscape or share them with friends.

You’ll enjoy creating interesting combinations with ornamental grasses and other plants in your landscape. With no trouble, they take their place in beds and borders, enriching neighboring plants with their presence.

Try a few ornamental grasses in your landscape. You will likely want more when you see how well they combine with other plants and how easy they are to take care of.