Selection, care, maintenance of ornamental grasses

By Sheila Cubick

OSU extension master gardener volunteer

Ornamental grasses are showing their true beauty in the landscape this time of year. These large masses move gently with the breeze and their lovely seed heads add interest to the garden.

They provide height, texture, movement and visual interest, especially during the winter months when many plants have died back. Ornamental grasses are quite forgiving of the extremes in both temperature and precipitation here in the Mahoning Valley. Choosing the correct grass for your site and purpose is important. Grasses that spread by rhizomes in a mat under the soil will work better as ground covers, while those that form clumps and spread outward by adding rings of growth are better as bedding plants or focal points in the landscape. Consider site characteristics such as the amount of light and moisture as well as horizontal and vertical space limits when choosing your grass species.

Once established, however, they do require some maintenance to retain health and beauty. They need to be cut down to about 4–6 inches to remove the dead material to ensure abundant new growth in spring. Leaving the dead material too long into March can delay warming of the crown, thus the beginning of new growth for several weeks. Cutting can be done in either fall or spring. However, leaving the foliage over the winter protects the crown and provides visual interest in the winter landscape. Personally, I like to leave the seed-heads as another food source for wildlife.

Removing the plant material also decreases the amount of nutrients being replaced in the soil around the plant. You will probably have to provide some fertilizer around the grasses in spring. Remember: Soil test first. Be sure what your soil, and therefore your plant, actually needs before wasting time, money and fertilizer.

As your clumping grasses age, they spread outwardly, sometimes leaving a hole in the center of the plant. This is unattractive and can possibly provide a moist environment for disease. Divide grasses by digging the clump and transplanting every two to three years. This should be done in spring or fall, but not in the summer after the plant‘s growth slows and ceases.

To regenerate, some gardeners burn the short grass clump in spring. While this is how grasslands regenerate in nature, it is not recommended for the home gardener. For a chart of grasses and characteristics to choose from for your garden, go to: http://go.osu.edu/fancygrasses.