Trimming Ornamental Grasses: A Guide to Proper Timing and Techniques

The ornamental grasses are a group of plants that can be used as landscaping plants in gardens. The majority of these perennials have a grass-like appearance and growth habit, and are grown more for their foliage than for their flowers. Some are grasses of the Poaceae family, but there are other plants, such as sedges and rushes that fall into this category.

They add texture, motion and sound to your garden when they rustle. Many ornamental grasses, which are native species of plants, are popular among gardeners interested in water-efficient and natural landscaping. Once the leaves turn brown, they will need to removed. It can be messy to remove dead ornamental grass, but you can make it easier by following some tips.

When to Cut Back Ornamental Grasses
The type of ornamental grass you have and your own personal preferences will determine when to cut it back. The job can be done in the fall, after the leaves have died. You can also leave the grass in place over the winter to cut back in spring.

Some ornamental grasses can remain attractive throughout the winter.1 At a time when most of the landscape looks rather dull, long grasses waving in the wind can add visual interest. Their seed heads are also a source of food for wildlife.

WARNING
Use ornamental grasses carefully if you live in an area where wildfires occur frequently. It’s better to remove the foliage at the end the growing season than to leave the dead grasses for their decorative appeal. A large clump dried grasses will burn faster than any other plant. Keep ornamental grasses away from structures and your home when you plant them. Authorities in some areas warn against planting any ornamental grasses or plants that can burn easily.

Before You Start
The three types of ornamental grasses include warm-season, cool-season, and evergreen. Seges and carex are two examples of evergreen “grasses” that don’t belong to the grass family and do not require pruning. They can, however, be divided into smaller plants if they become unruly. How do you identify the type of ornamental Grass you have and when you should prune it?

These grasses are primarily found in the spring, before temperatures reach 75 degrees Fahrenheit. They also grow in the fall when temperatures drop. These grasses retain their color without much growth during the summer heat. The cool season grasses need to be trimmed back very early in the spring. Once the snow has melted, trim the grass by two thirds and leave one-third intact. Too much pruning can damage the plant. Cool season grasses can include fescues (Blue Oat Grass (Helictotrichon), Deschampsia (tufted Air Grass), and Autumn Moor Grass (Sesleria).

Learn how to cut back ornamental grasses in spring and fall

The warm-season grasses start growing mid- to late spring or even in early summer. The grasses grow and flower more when temperatures are high. Winter turns warm-season grasses brown. Cut back ornamental grasses that don’t look good dormant in the fall if you like a neat garden or if they are a type of grass that does not look very nice. Many grasses can add great winter interest to the landscape by adding texture and movement when most of the garden has gone to sleep. Cut back the grasses to maintain interest in your garden through winter.

Cut these grasses to the ground when you prune them. Warm-season grasses can include Japanese silver grass, northern sea oats and perennial fountain grass. Hardy pampas (Erianthus), perennial Fountain grass (Pennisetum), Switchgrass (Panicum), or Prairie Cordgrass (Spartina) are all warm-season grasses.

Tip
Some ornamental grasses, particularly in northern climates, are only grown for one season. It is best to remove the roots to make room for new plants.

The Best Ornamental Grasses
Ornamental grass
What you’ll need
Equipment and Tools
Power hedge trimmers or pruning shears
Lawn Rake
Materials
Biodegradable tapes or bungee cords
Instructions
Cutting back ornamental grasses: Materials and tools

Tie Grass Into Bundles
When cutting ornamental grass, the messier the job can be. Bundle the stalks to reduce the mess. Wear gloves, as some grass blades are quite sharp. You can use any wide tape, provided it is sticky enough to stick to the grass. Eco-friendly paper tapes are recommended. Many gardeners prefer to use reusable bungee chords wrapped tightly around the grass as an alternative.

You may need to wrap the bundles of ornamental grass in two or more spots along the stems, depending on their height. The stalks of wide plants may need to be divided into at least two sections before bundling.

Yellow-green ornamental Grasses tied in bundle with green tape
Cut the Grass
Once the ornamental grass has been neatly bundled up, cut it with pruning shears, either to the ground for warm-season or by two thirds for cool season grass. As you cut, use the tape or bungees to hold the blades of grass in place.

A power hedge trimmer can be useful if your ornamental grasses are thick. In either case, try to cut the bundle without damaging it.

Yellow-green ornamental grass trimmed below green tape tie
Finish the Job
The bulk of your work is cutting each bundle. There will be some blades that are not in the bundle. You can remove them with pruning shears. Rake the area around your garden to remove any grass blades that may have escaped.

The grass that has been wrapped with biodegradable string or tape can be thrown whole in a municipal yard waste pile or compost heap. Remove the vinyl tape from the grass bundles if you used it.

Tip
Composting dead grass stalks will speed up decomposition if you cut them into small pieces. This is easy to accomplish if the bundles of grass stalks still have their ties. Add wet green material to the compost when you have a large amount of dead, dry grass. Add a few handfuls nitrogen fertilizer for the grass to break down.

Cut the yellow-green ornamental grasses at the middle of the dead leaves
The FAQ
When should ornamental grasses get cut back?
It’s best to leave an ornamental species of grass in place if it remains attractive throughout the winter. If the foliage on your plant species begins to deteriorate at the end season, it’s best to cut it in the fall.

What happens if ornamental grasses are not cut back?
You should cut back ornamental grasses to prevent them from spreading their seeds. They will look untidy and have depreciated leaves. Fresh foliage that grows in spring may have difficulty growing through depreciated leaves.

How far do you cut back ornamental grasses when cutting them?
The species will determine how much you need to trim your ornamental grasses. Cut back cool-season grasses by two-thirds, while warm-season ones can be trimmed to almost ground level.


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