Ornamental grasses are a popular choice in the garden, where their textures and colors provide distinct visual interest. And because many ornamental grasses are native species, they're favored among gardeners who are interested in natural and water-efficient landscaping. But once the foliage turns brown at the end of the growing season, gardeners must remove the dead grass. This job can be messy. So this tutorial shares some best practices to make the process fairly quick, easy, and tidy.
Equipment / Tools
- Pruning shears or a power hedge trimmer
- Lawn rake
- Biodegradable tape (or other material to bundle the grasses)
First, Know What Type of Grass You're Growing
Grass is grass, right? Not really! Ornamental grasses are grouped into three categories: warm season, cool season, and evergreen. Most evergreen "grasses" aren't really in the grass family, like sedges and carex--and those don't need pruning. (They can be divided if they get unruly.) But how do you know which type of ornamental grass you have, and when should you prune it?
Cool season grasses grow primarily in spring, before the temperatures exceed 75 degrees Fahrenheit, and in fall when temperatures cool. These grasses keep their color throughout summer without much growth during its heat. Cool season grasses should be cut back in very early spring. As soon as the snow clears, cut the grass back by 2/3, leaving 1/3 in place. Pruning too drastically can harm the plant.
Warm season grasses begin growing in mid to late spring, or even early summer. They thrive when the temperatures rise, with major growth and flowering occurring during summer's heat. Warm season grasses turn brown in winter. If you prefer a tidy garden, or if your ornamental grass is a variety that doesn't look great dormant, cut back the grass in fall. However, many grasses add terrific winter interest in the landscape, adding movement and texture when much of the garden is asleep. The seedheads of many grasses also provide food for wildlife. If you want to keep some interest in your garden throughout the winter, cut back these grasses in mid to late spring. Cut warm season grasses to the ground.
Bundle the Grass
The fuller the ornamental grass is, the messier it can be when cutting it down. To lessen the mess, start by bundling the stalks. Wear gloves--some grass blades can be quite sharp. Any wide tape will do, as long as it's sticky enough to adhere to the grass. Biodegradable paper tape is recommended for an eco-friendly approach. As an alternative, many gardeners like to use bungee cords stretched tightly around the grass.
Depending on the height of the ornamental grass, you might need to wrap each bundle of grass in two or three spots along the length of the stems. And especially wide plants might need to have their stalks divided into two or more sections before bundling.
Cut the Grass
Now that the ornamental grass is neatly bundled, take your pruning shears and cut the grass, either by two-thirds for cool season grass, or to ground level for warm season grass. With the tape or bungee cords holding the grass blades in place, lean the bundle away from its base as you cut.
If your ornamental grass is thick, a power hedge trimmer might be helpful to do the job. Either way, aim to keep the bundle intact as you cut.
Finish the Job
Cutting each grass bundle is the bulk of the job. But there will undoubtedly be a few renegade blades outside of the bundle to clean up with pruning shears. Finish by raking the garden area to catch any loose blades of grass.
Picking up the bundles to take to the lawn waste or compost pile is generally an easy task, but removing the tape can be a hassle. This is why biodegradable tape that you can leave on (or bungees you can easily remove) is helpful. If your only option is vinyl tape, remove it as best as you can. Any small remnants can be sifted out when you use the finished compost.
When to Cut Back Ornamental Grasses
It's a matter of type of grass and personal choice when you cut back your ornamental grasses. You can do the job in the fall after they die or leave them in place through the winter and cut them in the spring.
Many ornamental grasses will remain attractive through the better part of the winter. And at a time when the rest of the landscape is rather dreary, long grasses swaying in the breeze can add some visual interest. Plus, their seed heads can provide food for wildlife.
Tips for Cutting Back Ornamental Grasses
Most ornamental grasses are perennial plants, coming back year after year. But a few are grown as annuals that last for just one growing season, especially in cold northern climates. For these, it is best to dig out the roots of the plants after bundling and cutting off the stems to prepare the planting site for something new.
If you are composting the dead grass stalks, cut them in pieces before you add them to the compost pile to speed decomposition. It's easy to do this if the grass stalks are still tied together in bundles. When composting large volumes of dry, dead grass, balance the mixture by adding wet, green material. Or add a few handfuls of nitrogen fertilizer to help the grass break down.
Maintenance of Ornamental Grasses. University of Illinois Extension