Adding texture, movement, and a unique look to any garden is what ornamental grasses do. Popular types like miscanthus, pennisetum, and schizachyrium have leaves that are a rainbow of colors and look nice all year. When winter comes, the dried leaves and seed heads stay put and sway gracefully in the wind. Even though ornamental grasses don’t need much care, they need to be pruned regularly to keep them looking their best. This article will show you when and how to cut back ornamental grasses so they grow well and look their best.
When to Trim Ornamental Grasses
The timing for cutting back ornamental grasses depends on whether they are cool-season or warm-season varieties.
Cool-Season Grasses
Cut back cool-season grasses in early spring as soon as new growth begins to emerge. Popular cool-season grasses include blue oat grass tufted hair grass, and many types of fescue. Pruning too severely can damage cool-season grasses, so leave about one-third of the foliage in place when trimming in spring.
Warm-Season Grasses
Warm-season grasses can be cut back anytime between late fall and mid-spring. For best results, trim miscanthus, switch grass, and other warm-season varieties to within a few inches of the ground before new growth emerges in spring. Cutting warm-season grasses in fall gives a tidy look but spring pruning allows the foliage to provide winter interest.
How to Cut Back Ornamental Grasses
Follow these simple steps for cutting ornamental grasses cleanly and efficiently:
Gather Supplies
- Pruning shears, loppers, or hedge trimmers
- Raffia, twine, or rubber bands for tying grass bundles
- Rake for clearing clippings
- Wheelbarrow for hauling clippings (optional)
- Work gloves and eye protection
Tie Foliage in Bundles
Before you cut, gather the stems together and use raffia or twine to tie them into bundles. This keeps the foliage neat and upright for easier trimming. For large grasses, divide into smaller bundles.
Cut Back Foliage
Trim the bundles back to the desired height using sharp bypass pruners, loppers, or hedge trimmers. Remove any remaining loose foliage with hand pruners.
Dispose of Clippings
Place tied bundles directly into yard waste bags or a compost pile. Rake up any loose blades.
Extra Tips for Cutting Ornamental Grasses
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Wear protective gloves and eyewear – grass blades can be sharp.
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Use clean, sharpened tools for easiest cutting.
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Recycle grass bundles as mulch or add to the compost pile.
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Remove dead foliage from evergreen grasses like carex by combing it out with your fingers.
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For overgrown grasses, use a string trimmer or small chainsaw to cut back.
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Divide congested clumps every 2-3 years in early spring to promote vigor.
Cutting back ornamental grasses the right way keeps them clean and healthy and brings out their beautiful shapes. Follow these guidelines for the best results. If you take care of ornamental grasses once a year, they will be a beautiful, low-maintenance addition to gardens and landscapes for many years.
Warm vs. Cool Season Grasses
You can cut back warm season grasses that are planted in mild winter areas in the fall if you want them to look better and not have their leaves and big fluffy seed heads blowing around your yard all winter.
For grasses and sedges that stay green all year in warmer places, it’s helpful to gently rake or comb through the grassy leaves and cut off any old, brown leaves. Every few years it may be necessary to trim these plants down removing at least 2/3 of the old tops to give them a fresh start. This too should be done in spring before they start to grow.
Cool Season Grasses should only be pruned in the spring, unless they have a disease or were broken during the summer storm or garden work.
When To Go Ahead & Prune
Most Grasses are cut back to expose the crowns to sunlight and to eliminate a place for unwanted animals and insects to overwinter. Luckily this is rarely the case, and you can give the crowns their annual clean out in the spring. It is best to remove all of the old grass blades and flowering stems down to just a couple of inches each spring so the fresh new foliage can grow without the old dried foliage holding it back.
A good rule of thumb is that if any of your annuals or perennials (including Ornamental Perennial Grasses) have had some diseased foliage this year, then it is recommended to cut and remove all infected debris from the site. Prevent most of your issues by planting your grasses where the soil is well-drained to keep them healthy.
Dispose of them at your local yard waste site to prevent the disease from overwintering on last year’s foliage or spreading potentially to other plants.
Another reason for some Ornamental Grasses to warrant being trimmed in autumn is if they are the type that may self-seed and make themselves a nuisance elsewhere. Nature Hills uses Plant Sentry to ensure you won’t receive a plant that may cause trouble in your area in the first place, but sometimes you buy a home with something prolific already there, so pruning off the seedheads before the seed matures to prevent spreading.
The BEST Way to Prune Ornamental Grasses
FAQ
Should ornamental grasses be cut back?
Yes, ornamental grasses should be cut back, typically in late winter or early spring before new growth emerges. Cutting them back helps remove old, dead foliage, promotes fresh growth, and prevents the build-up of debris.
What is the best tool for cutting ornamental grasses?
A small garden scythe is the best tool for the job, but you can also use a sharp bread knife with serrated edges. The key is in grabbing the grass like a ponytail and then cutting through the bottom of the stems quickly and efficiently. Think Uma Thurman against the Crazy 88 in Kill Bill.
What is the lifespan of an ornamental grass?
Ornamental grasses have a lifespan ranging from 3 to 10 years, influenced by species and growing conditions. Many are perennials, thriving for several years, while some are shorter-lived annuals.
Can I use a hedge trimmer to cut ornamental grass?
Hedge trimmers have taken the work out of cutting back ornamental grasses. Every garden design needs a few ornamental grasses, but cutting them back can be a lot of work without the proper garden tool. Electric, gas or battery operated hedge trimmers are important gardening tools to add to your spring clean-up tool.