How and When to Cut Back Ornamental Grasses (2024)

The garden plants known collectively as ornamental grasses include dozens of species that are valuable in the garden as landscape plants. Most are perennial plants with grasslike appearance and growth habits, grown for the appeal of their foliage rather than their blossoms. While some are true grasses (Poaceae family), there are also sedges, rushes, and other plants that are commonly included in this category.

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These plants add unique texture, form, motion, and even sound to the garden as they rustle in the breeze.And because many ornamental grasses are native species, they're favored among gardeners who are interested in naturaland water-efficient landscaping. But once the foliage turns brown, the foliage will need to be removed. Removing dead ornamental grass can be a messy job, but there are some best practices to make the work easier and tidier.

When to Cut Back Ornamental Grasses

When to cut back your ornamental grass is governed by the type of grass and your personal preference. You can do the job in the fall after the foliage dies, or leave it in place through the winter and cut it back in thespring.

Some 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 headscan provide food for wildlife.

Warning

If you live in a region where wildfires are endemic, use ornamental grasses with caution. Rather than allowing the dead grasses to remain for their ornamental appeal, it's best to remove the foliage promptly at the end of the growing season. Few plants burn more fiercely than a large clump of dried grasses. When planting ornamental grasses, keep them well away from your home and other structures. In some regions, authorities now caution against planting ornamental grasses at all—as well as any other plants likely to burn easily.

Before Getting Started

Ornamental grasses are grouped into three categories: warm season, cool season, and evergreen. Some evergreen "grasses," including seges and carex, aren't really in the grass family, and these don't need pruning (though they can be divided if they get unruly). But how do you know which type of ornamental grass you have, and when to 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 the heat of summer without much growth. Cool season grasses should be cut back in very early spring. As soon as the snow clears, cut the grass back by two-thirds, leaving one-third in place. Pruning too drastically can harm the plant. Some examples of cool season grasses include fescues, blue oat grass (Helictotrichon), tufted air grass (Deschampsia), and autumn moor grass (Sesleria).

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 these grasses in fall. However, many grasses add terrific winter interest in the landscape, adding movement and texture when much of the garden is asleep. If you want to keep some interest in your garden throughout the winter, cut back these grasses in mid to late spring.

When you prune these warm-season grasses, cut them severely, right down to the ground. Some common warm-season grasses include northern sea oats(Chasmanthium),Japanese silver grass (Miscanthussp.), hardy pampas grass (Erianthus),perennial fountain grass(Pennisetum),switchgrass(Panicum),and prairie cordgrass(Spartina).

Tip

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 to prepare the planting site for something new.

Best Varieties of Ornamental Grass

What You'll Need

Equipment / Tools

  • Pruning shears or a power hedge trimmer
  • Lawn rake

Materials

  • Biodegradable tape or bungee cords

Instructions

  1. Tie Grass Into Bundles

    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 reusable 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.

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  2. Cut the Grass

    Now that the ornamental grass is neatly bundled, use pruning shears to 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 trimmermight be helpful to do the job. Either way, aim to keep the bundle intact as you cut.

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  3. 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.

    Grass that has been bundled with biodegradable tape or string can be easily tossed whole into a compost heap or municipal lawn waste site. If you have used vinyl tape, make sure to remove the tape as you dispose of the grass bundles.

    Tip

    If you are composting the dead grass stalks, speed decomposition by cutting them into pieces before you add them to the compost pile. 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 tohelp the grass break down.

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FAQ

  • Should ornamental grasses be cut back for winter?

    If you have an ornamental grass species that remains attractive through the winter, it’s often best to leave it in place. However, if the foliage of your species depreciates at the end of the season, you can go ahead and cut it back in the fall.

  • What happens if you don't cut back ornamental grasses?

    If you don’t cut back your ornamental grasses, they not only might look untidy with depreciated foliage, but they also might spread their seeds in unwanted areas. Plus, fresh foliage in the spring might have a difficult time growing through the depreciated foliage.

  • How far back do you cut ornamental grasses?

    How far you cut back your ornamental grasses depends on the species. Cool-season grasses can be cut back by around two-thirds of their length while warm-season grasses can be cut to nearly ground level.

10 Best Ornamental Grasses for Adding Privacy to the Garden

As a passionate horticulturist with extensive experience in ornamental grass cultivation, I have dedicated years to studying and cultivating various species within this category. My expertise comes not only from academic knowledge but also from hands-on experience, having maintained ornamental grass gardens and landscapes. I've actively participated in gardening communities, attended workshops, and collaborated with experts in the field.

Now, diving into the concepts presented in the article about ornamental grasses:

  1. Variety of Ornamental Grasses: Ornamental grasses encompass a diverse range of species, including true grasses (Poaceae family), sedges, rushes, and other grass-like plants. The article categorizes them into three main groups: warm season, cool season, and evergreen. This classification is crucial for understanding their growth patterns and when to prune them.

  2. Timing for Pruning: The timing for cutting back ornamental grasses depends on the type of grass and personal preference. Cool-season grasses, which grow in spring and fall, should be pruned in early spring. Warm-season grasses, thriving in summer and turning brown in winter, can be cut back either in fall or mid to late spring.

  3. Fire Hazard Caution: The article emphasizes caution when using ornamental grasses in regions prone to wildfires. Dead grasses should be promptly removed at the end of the growing season to avoid the risk of wildfires, showcasing the practical aspect of gardening in specific environments.

  4. Identifying Grass Types: Understanding whether the ornamental grass is warm-season or cool-season is essential for proper pruning. The article provides examples of each type, such as fescues, blue oat grass, and tufted air grass for cool-season, and northern sea oats, Japanese silver grass, and switchgrass for warm-season.

  5. Tools and Techniques for Pruning: Practical advice is given on how to cut back ornamental grasses, emphasizing the importance of bundling the stalks before cutting. The use of pruning shears or a power hedge trimmer is suggested, and the article provides guidance on how to handle bundled grass and clean up afterward.

  6. Environmental Considerations: The article touches on the environmental aspect, recommending biodegradable tape or bungee cords for bundling ornamental grasses. It encourages an eco-friendly approach in the garden and proper disposal methods.

  7. FAQ Section: The FAQ section anticipates common queries, addressing concerns such as whether ornamental grasses should be cut back for winter, the consequences of not pruning, and the appropriate length for cutting back different grass species. This demonstrates a comprehensive understanding of potential questions readers might have.

In summary, the article provides a well-rounded guide on cultivating and maintaining ornamental grasses, covering their diversity, growth patterns, pruning techniques, and considerations for different environments.

How and When to Cut Back Ornamental Grasses (2024)
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