Ornamental grasses are essential garden plants for their naturalistic beauty, year-round interest, fine textures, drought tolerance, and resistance to insects and pests. When planted in the right site, they’re also low-care perennials that require little more than an annual haircut. The timing of when to cut back ornamental grasses is important to ensure they’re trimmed before the new growth begins, but not so early that you forfeit winter interest. Keep reading to learn everything you need to know about when to cut back ornamental grasses.
Why you need to know when to cut back ornamental grasses
Cutting back ornamental grasses is an important annual garden task. It keep the plants looking tidy – with no dead leaves and stems – but, depending on the species, also prevents the spread of seeds into other areas of your garden and landscape. Plus, getting rid of dead growth ensures the fresh new blades of grass can grow without obstruction.
As noted above, timing is important when it comes to pruning back ornamental grasses like maiden grass and feather reed grass. If you prune them back too early you’ll miss out on their spectacular winter foliage and inflorescences. They also provide winter protection, and sometimes seeds, for wildlife like birds. However, if you wait too long to cut them back you may accidentally damage the blades of grass by removing the new growth. Instead of having pointed leaf tips they’ll have blunt or flat tips which can impact the appearance of the plant.
Types of ornamental grasses
Ornamental grasses are generally divided into two groups: cool-season grasses and warm-season grasses. Cool season grasses include blue fescue, feather reed grass, and tufted hair grass. Their foliage emerges in early spring, or even mid to late winter if you live in a mild climate. This is followed by summer flowers which add long-lasting beauty to the landscape.
Warm season grasses are slower to start in spring, a trait that often has gardeners worried that they didn’t survive winter. However, once the temperatures warm up, these grasses begin to grow. Growth continues throughout summer and by late summer and into autumn the flowers appear. The showy panicles provide late season interest that persists long into winter. Popular types of warm season grasses include maiden grass, big bluestem, fountain grass, and switchgrass.
There are other types of plants grouped with ornamental grasses because they have similar forms and foliage. Often called ‘evergreen grasses’ these plants include sedges like Pennsylvania sedge and Evergold, which has gorgeous green and cream leaves.
When to cut back ornamental grasses
The timing of when to cut back ornamental grasses is determined by several factors including the type of grass and your climate. For example, mild climate gardeners cut their grasses back earlier than cold climate gardeners. Typically January is the season to prune ornamental grasses in zones 7 and up. This ensures they’re cut back before the new growth begins. As a cold climate gardener who lives in zone 5 I don’t cut back my ornamental grasses until late winter, usually sometime in late February or March when the weather cooperates. I like to wait until the snow melts and I can see what I’m doing.
As for types of grasses, most cool and warm season species benefit from being cut back when dormant. Evergreen grasses, again not true grasses but plants like sedges, don’t recover as well or as quickly when hard pruned. For this reason instead of cutting them back hard, the dead leaves and stems are often removed by selective pruning. Or you can run a gloved hand through the plant to comb out the brown leaves.
The best tools to cut back ornamental grasses
Having the right tool makes cutting back grasses quicker and easier. My go-to tool is a pair of hedge trimmers, but you can also use hand pruners, a sickle, and more. Let’s look closer at these tools to help you pick the best ones for your garden.
- Hand pruners – I use hand pruners to cut back small clumps of grasses. They’re also handy for cutting back larger grasses, but with such a small blade, it takes longer to get through all the stems.
- Hedging shears – Hedge shears, also called hedge trimmers, look like large scissors and are designed to cut through a lot of thin stems at once. They’re great for cutting back most types of grasses (I even use them to cut back hydrangeas, depending on the type). You can also use a power hedge trimmer if you have one.
- Loppers – Loppers are a long-handled pruning tool designed to cut through woody stems, up to 2 inches in diameter. I use them to prune shrubs and trees, but they’re also great for trimming ornamental grasses, particularly giant miscanthus which has very woody stems.
- Sickles or scythes – Sickles and scythes are a cutting tools with curved blades and are traditionally used to harvest cereal crops and hay. I have a hand sickle that I use to cut back grass clumps like those of maiden grass.
- String trimmers – I love the height and form of giant miscanthus, a type of maiden grass that grows 9 to 12 feet tall. However cutting it back with hand pruners or hedge trimmers is a challenge as the mature stems are tough and woody – much like bamboo. Instead I use my string trimmer in early spring to cut back the old growth to about 10 inches.
Getting ready to cut back ornamental grasses
The first step is to gather your tools and put on the right clothes. When I’m working in the garden, especially when cutting back plants, I like to put on a long-sleeved shirt, long pants, eye protection, and of course I always wear gloves. The leaf blades of many ornamental grasses have sharp edges and pointy tips and can prick you or give you a paper cut-like slice if you’re not careful.
Next, you’ll need your cutting tools and some rope, twine, masking tape, or bungee cords. Use these to secure the clump of grass. Securing the foliage keeps the plant upright as you prune, making it easier to cut. It also prevents the lightweight leaves from blowing away in the wind. Securing the grass also makes clean-up a snap. Just carry the bundle to your compost pile, remove the tape or ties, and spread it on top to break down.
How to cut back short ornamental grasses
Shear compact types of grass, like Japanese forest grass, fountain grass, Japanese blood grass, and blue fescue, back before the new growth begins in late winter. I like to use hedging shears, but you can also use hand pruners for this job. However, hedging shears are much faster, especially if you have a lot of plants to cut back. Trim the old growth back to 2 to 3 inches above the ground. Gather or rake up the spent growth and add it to your compost pile. I have a pair of hand rakes that are perfect for scooping up the clipped grasses.
How to cut back tall ornamental grasses
Next up I want to offer some tips on how to cut back tall ornamental grasses like maiden grass, big bluestem, and feather reed grass. This job takes a bit more preparation than clipping short grasses but it isn’t difficult Here is a step by step guide to trimming back tall grasses:
Step 1: Gather your tools
Cut back tall types of ornamental grasses with a heavy duty tool like hedge shears, a sickle, a scythe, a hedge trimmer, or a string trimmer. I also grab a roll of masking tape or twine to bundle up the grass and make cutting it back easier. I have a garden tote I use to keep everything organized and close at hand.
Step 2: Secure the grass
If I’m using a string trimmer I don’t bother with this step. If I’m using a hand tool gathering all the old growth into a bundle using twine, tape, or a bungee cord makes it much easier to slice through the blades of grass. To do, just wrap the tape, twine, rope, or bungee cord around the plant to create a tight upright clump of grass. If they’re very wide grass stands it’s best to divide them into several separate upright bundles.
Step 3: Cutting back
With your tool of choice, cut the grass back to the right height, typically 6 to 10 inches, depending on the plant. Clip feather reed grass and switch grass back to 6 inches and giant miscanthus to 10 inches. It’s best to cut or shear small bundles of stems working your way from one side of the plant to the other. After cutting through the dense plant clean up any stray blades of grass with hand pruners or hedge shears.
Step 4: Collect the debris
Cutting back grasses is messy! The dry old foliage of maiden grass, for example, can blow all around as you cut back the plant. Tying up the stems reduces the mess. Afterwards, clean up any scattered foliage with hand rakes or a garden rake. I carry the bundles of grass to my compost area, adding the stems and stalks to a compost pile or my rolling compost bin. I save very woody stems, like those of giant miscanthus, using them as bamboo stakes in my vegetable garden. They don’t compost well and are perfect for holding up crops like peppers and eggplants.
For more information on growing ornamental grasses, be sure to check out these detailed articles:
- How to grow Pennsylvania sedge
- The best meadow grasses for native planting
- How to plant grass seed
- Invasive garden plants: 10 to avoid
Did I answer your question about when to cut back ornamental grasses?