Ornamental grass requires little to no maintenance beyond cutting it back and dividing it when it grows too large and unruly.
Spring is when your ornamental grass needs the most attention, so prepare to cut back foliage and divide overcrowded clumps once the soil thaws and temperatures rise.
In summer, monitor the grass for disease and drought stress (which are, fortunately, uncommon problems with ornamental grass). Once fall and winter come around, simply enjoy the sound, color, and movement ornamental grass brings to the landscape.
You don’t need a very green thumb to take care of ornamental grasses, although if they are part of a large, more complicated garden, you might consider using a professional gardener.
Spring
Cut it back
Spring is the best time to cut back your ornamental grass. Cut back your cool-season and warm-season grasses before new growth begins and the threat of frost has passed.
For cool-season grasses, the cut-back window is late winter to early spring. If you’re growing warm-season grasses, schedule the cut in mid to late spring.
Improper cutting technique can lead to messy spring cleanup, damage to the plant, and loss of habitat.
For more, check out these guides:
How to Cut Back Ornamental Grasses
When to Cut Back Ornamental Grasses
Divide overcrowded clumps
You don’t have to divide ornamental grass annually. They typically need to be divided every two to five years.
Aaron Steil, Consumer Horticulture Extension specialist with Iowa State University Extension and Outreach, recommends dividing ornamental grasses just as new growth emerges in spring.
Here’s why: Ornamental grass develops a dead center as it ages, which is a sign the plant is ready for division. “Waiting until the foliage begins to emerge allows you to see and remove this dead area when splitting the clump into pieces,” Steil says.
He adds, “Many ornamental grasses also do well with late-season division, in late summer or early fall.”
For a step-by-step breakdown of this spring chore, visit our guide on How to Divide Ornamental Grasses.
Water new plantings deeply
New plantings require plenty of water, so whether you’ve planted a new grass from your local nursery or divided an old clump, water the plant deeply and infrequently to promote deep roots.
David Lowenstein, Consumer Horticulture Extension educator with Michigan State University Extension, recommends giving newly planted ornamental grasses 1 inch of water per week in the first month to month and a half.
“In their second and future years, they should not require any supplemental watering. Most grasses and sedges have deep roots and tolerate drought conditions,” he adds.
Apply mulch
As new growth begins in spring, you may notice a surge in weeds. Lowenstein recommends applying 2 to 3 inches of mulch to the garden bed to suppress weeds.
| Pro Tip: Do not smother the plant with mulch. Apply the mulch 2 to 3 inches away from the plant’s base. |
Fertilize (only if necessary)
It’s tempting to provide your plants with a nutritional boost. But fertilizing your ornamental grass, especially with the wrong fertilizer, might do more harm than good.
“Most ornamental grasses need very little fertilizer,” says Barbara Smith, Consumer horticulturist with the Clemson Extension Home and Garden Information Center.
Excess nitrogen in the soil can promote disease, weak stems, and overly vigorous growth, she says. If fertilizer becomes necessary, Smith recommends doing a soil test to determine what the plant needs.
If your soil test calls for fertilizer, visit our guide on understanding fertilizer ratios to ensure a balanced application.
Summer
Monitor for disease
Pests and diseases are rarely an issue with ornamental grasses. Rust and anthracnose are occasionally a problem, however, this is often due to poor maintenance practices or improper growing conditions.
To encourage recovery, dial back on the fertilizer and trim nearby vegetation to allow more air circulation and sunlight.
Ornamental grasses growing in containers often suffer from root rot due to overwatering. If the soil is water logged and your plant is drooping, allow the soil to dry and adjust your watering schedule accordingly.
Don’t trim
Your cool-season grass might be slowing down in summer, but this is not a sign of die back. Growth will pick up again in fall.
Summer is your warm-season grasses active growing season, so there’s no need to trim.
Water (if necessary)
In general, most ornamental grasses don’t require a lot of water, but every garden is different.
“Once established, moisture needs vary by grass species, soil type, temperature, and other factors,” says Smith.
The best way to determine your summer watering schedule is to identify the plant variety, understand the conditions it’s growing in, and monitor for drooping, browning, and other signs of drought stress.
Fall and Winter
Leave foliage intact (with one exception)
As temperatures begin to drop, your grasses will enter dormancy. Warm-season grasses will enter dormancy in fall, while cool-season grasses die back in winter.
Before you grab your pruning shears, allow the foliage to remain intact throughout fall and winter. Delaying the trim until spring protects the base of the plant from winter injury by providing insulation, advises Matthew McKernan, horticulture agent at K-State Research and Extension in Sedgwick County.
Plus, tall grass brings sound, color, and beauty to a winter landscape, and provides shelter for pollinators, birds, and other wildlife.
However, if you live in an area threatened by wildfires, cut your warm-season grass in fall as soon as it dies back.
Reduce watering
Your ornamental grass likely won’t need supplemental watering in the fall as temperatures cool and rainfall increases. Watering during this time can lead to waterlogged soils and rotting roots.
Common maintenance problems
If your grass is flopping, browning, or spreading aggressively, the cause is often too much fertilizer or irrigation. Remember, less is more when it comes to caring for your ornamental grass.
Overgrowth can also occur if the plant itself is invasive. Many grasses, such as pampas grass, are considered invasive in certain regions. To learn more about its invasive qualities, visit our article Why Is Pampas Grass Bad?
Before planting, check that the species is native to your area. Sterile cultivars are also good alternatives to some invasive varieties, such Chinese silver grass and fountain grass. If you already have an invasive grass established, transplanting it into a container can help prevent it from spreading.
FAQ about caring for ornamental grass
Evergreen ornamental grasses, such as sedges or rushes, are vibrant all year round and don’t require a cut back. Instead, selectively prune by gently combing your gloved hand through the foliage to remove any dead material.
To prevent the grass from flying everywhere, bundle the grass with string, rope, or a bungee cord before you cut. Have a wheelbarrow or tarp on standby to help you relocate the grass.
If your grass grows most actively in the summer, then you’re likely growing warm-season grass. Cool-season grass thrives in spring and fall and slows down during summer.
Sedges and rushes remain evergreen all year long and do not enter dormancy.
Whether you grow warm-season, cool-season, or evergreen ornamental grass will determine how you time your maintenance practices, particularly division and trimming.
Hire a lawn care pro
While you’re satisfying your green thumb and giving your garden beds TLC, don’t let your lawn go overlooked. Hire a lawn care pro through Lawn Love to mow, fertilize, and remove weeds so that you can focus on your ornamental grasses.
Main Image: A person is watering a clump of ornamental grass with a watering can. Photo Credit: Adam / Adobe Stock
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