How to trim ornamental grasses: when and how to prune the different types (2023)

Finding out how to trim ornamental grasses means first establishing what type yours is. Many varieties only need minimal pruning and cutting back, while other types need a hard chop to tidy them up. Whichever option is right for your ornamental grass the good news is that it's easy to do, which makes them a top choice if you’re after a low-maintenance option.

Evergreen grasses are the easy option as they can be left to get on with it all year-round apart from occasionally removing any dead foliage. Meanwhile, the deciduous varieties of ornamental grass tend to fizzle out at the end of summer when their foliage turns brown and straw-like, so they will need cutting back hard once a year to keep them looking their best. There are also semi-evergreen grasses to add to the mix.

Knowing the optimum pruning time is a key part of learning how to grow ornamental grasses, so make sure you are up to speed with the correct time of year and the right methods for doing it.

How to trim ornamental grasses: when and how to prune the different types (1)

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Expert guide on how to trim ornamental grasses

It might seem that autumn is the natural time to tidy up many different types of ornamental grass as part of your fall gardening checklist, but it's worth pointing out you shouldn't be in too much of a hurry.

(Video) The BEST Way to Prune Ornamental Grasses

'Many ornamental grasses have excellent winter presence, adding beauty and interest, while also providing important cover for wildlife through the cold months,' says Beth Chatto Gardens (opens in new tab) head gardener Åsa Gregers-Warg. 'The perfect time to cut many of them back is when late winter begins to give way to early spring, before new foliage appears.'

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(Image credit: Beth Chatto’s Plants & Gardens)

Expert tips how to trim evergreen ornamental grasses

Evergreen ornamental grasses don't require hard pruning. It's more a case of tidying them up rather than getting stuck in with your best secateurs.'They provide texture, movement, softness, transparency and interest for the winter garden as they look lovely with a hoar frost,' says garden designer Jane Bingham (opens in new tab).It's certainly one of the main reasons why gardener Monty Don's favorite ornamental grasses for fall color look so impressive in his own garden during the cooler months.

'Evergreen grasses such as Deschampsia (Tufted Hair Grass) and Luzula (Snowy Woodrush) keep their foliage in all seasons, so trimming them in the conventional sense is not necessary,' says Morris Hankinson of Hopes Groves Nurseries (opens in new tab). Usually, a comb or pull-through in spring is all that's needed. 'Don’t forget to wear thick protective gardening gloves,' adds Morris. 'Some of these grasses are tough and will give you a sharp cut or two on unprotected skin.'

(Video) When and How to Prune Your Grasses

Other popular evergreen grasses that can be tidied in spring include Festuca glauca, and varieties of Carex. Remember that all evergreen grasses are an excellent choice if you like landscaping with grasses as they offer interest year round.

'To keep evergreen grasses likeStipa giganteaandPoa labillardiereilooking good cut them back to a neat dome-shape,' says Åsa Gregers-Warg. 'Gently groom to remove any old thatch by running a rake or your hands (wear gloves!) through the grass. As the new growth emerges they look not unlike shaving brushes.'

Follow these simple tips to keep them looking their best.

  1. Start by removing any brown tips and cutting back dead foliage that may have built up around the perimeter at the base of the plant.
  2. Spent flowering stalks can be cut off, and any unsightly leaves removed. Comb your fingers through the clump at the same time to sift out any faded foliage.
  3. Water the clump with the spray attachment of the garden hose to freshen it up and water away any loose debris.
  4. Apply a liquid fertilizer to your ornamental grass to give the new growth a head start.

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(Image credit: Beth Chatto’s Plants & Gardens)

How to trim deciduous ornamental grasses in a few simple steps

Popular deciduous ornamental grasses that benefit from hard cutting back as part of your spring garden jobs include Miscanthus, Calamagrostisxacutiflora'Karl Foerster' andDeschampsia cespitosa'Goldtau'. They should be trimmed to ground level before fresh growth starts to emerge in early spring.

(Video) Cutting Back, Replanting & Dividing Ornamental Grasses

Deciduous grasses such as miscanthus, panicum and calamagrostis are cut back to two or three inches from the ground with garden shears or secateurs. 'There are a few exceptions:Pennisetum orientaleandP.villosumare slightly more more tender and will come into growth later, so are usually left until mid spring to protect the crown,' explains Åsa Gregers-Warg. 'Grasses like Molinia and hakonechloa die back in fall and as ours are underplanted with early flowering bulbs, we tend to rake away the collapsed stems before Christmas.'

'Deciduous grasses such as Imperata (Japanese Blood Grass) and Chasmanthium (Sea Oats) die right back every winter,' says Morris Hankinson. 'Simply chop them back close to ground level in spring when the weather warms, but before the plants show new growth.'

These simple steps will ensure your deciduous grass looks its best once it bursts into new growth.

  1. The ideal time to trim deciduous grasses is in spring before the new growth shoots up. Your clump of grass is probably not looking it's best at this time as it will be full of dead leaves that have accumulated since last fall.
  2. Start by combing through the plant with your fingers to remove any dead foliage that sheds easily. It's a good idea to wear gloves.
  3. Next grab loose handfuls of dead stems and begin to cut them back hard with secateurs. This needs to be done carefully so you don't damage any new growth.
  4. Tackle the crown of the plant where it forms a clump at soil level and the stems emerge. Again, be careful you don't accidentally snip any fresh green shoots. Aim to cut the clump back to a few centimetres, making sure you get rid of any dead or tired looking old stems. Pick out any dead leaves that may have accumulated in the crown.
  5. Now is a good opportunity to clear the clump of any weeds that may have popped up either in it or in the surrounding area.
  6. If the clump of grass looks dry given it a quick spray of water to spruce it up and clear away any remaining debris.
  7. Now feed your ornamental grass with a general fertilizer to give it a boost as the new growth will start to emerge more freely now it has been trimmed back.

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(Image credit: Beth Chatto’s Plants & Gardens)

How do you trim semi-evergreen ornamental grasses?

There is another category of ornamental grasses where you need to go with the flow. Semi-evergreen grasses drop their leaves in cold winters but keep them if it is mild, adding interest to your winter landscaping.

(Video) Trimming ornamental grasses

'Semi-evergreen grassessuch as Koeleria (Blue Hair Grass) and Stipa (Golden Oats and Pony Tail Grasses) usually keep their foliage right through winter unless it’s very cold in which case they will likely die back,' explains Morris Hankinson. 'In a normal season treat them like evergreens, combing and pulling at any dead leaves and snipping back the old flower stems.' If they die right back after a cold winter then chop them back in the same way as you would deciduous grasses.

Stipa tenuissimais a popular ornamental grass that is semi-evergreen and can easily look scruffy after the winter. 'I was told when I first started working as a gardener not to cut them back too hard as they might die,' says Åsa Gregers-Warg. 'Perhaps this is because we’re on free draining soil in a mild climate here at Beth Chatto Gardens, so they don’t seem to mind the harsh treatment of thatch being pulled out and being trimmed back to a couple of inches from the ground. It’s all about trial and error when it comes to how to trim ornamental grasses as all keen gardeners know.'

How to trim ornamental grasses: when and how to prune the different types (5)

(Image credit: Beth Chatto’s Plants & Gardens)

'There are several different tools you can use when pruning ornamental grasses, it really depends on the size and age of the plant,' says Paul Hicks, product manager at Stihl (opens in new tab).

'For small or young plants we recommend using a pair of the secateurs and for mid-sized plants it might be better to opt for a battery powered tool, such as the Stihl HSA 26 (opens in new tab), which makes light work of the task while also keeping you in control of what you want to remove.'

(Video) Do you trim your ornamental grasses in the fall or spring?

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(Image credit: Stihl)


Which ornamental grasses should be cut back? ›

Nearly all ornamental grasses can be cut back anytime from early fall to late Spring. Even if a grass becomes too large during the growing season, they can be pruned for shape. Simple shear off a bit of top growth as needed. Ornamental Grass Care Tips -Grasses can be cut back nearly anytime from fall to spring.

How and when do you trim ornamental grasses? ›

Cut back cool-season grasses in very early spring.

Leave their foliage in place until spring and then as soon as the snow is gone cut them back. Leave about 1/3 of the plant in place. Trimming cool-season grasses too harshly can irreparably harm the plant.

How far do I cut back ornamental grasses? ›

Warm-season grasses that are taller than three feet should be cut back to four to six inches from ground level. Shorter mature plants can be cut back to about three inches. Prune cool-season grasses back by two-thirds.

Do all ornamental grasses need to be cut back? ›

Once established, ornamental grasses have few needs. “The big thing with grasses is cutting them back once a year and dividing them once every four or five years,” Dori says. Most gardeners leave their native grasses in place for winter interest and to provide food for birds.

What happens if you dont 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.

What time of year do you cut back grasses? ›

All forms of deciduous grass are best cut back in the spring, about March depending on the weather; ideally just as the new shoots are coming through. Just like lawns cutting new growths along with the old will not harm the plant.

Should decorative grasses be cut back in fall? ›

Some people prefer to cut these grasses back in the fall, as they don't care for the floppy look throughout the winter, but the foliage actually helps to insulate the crown of the plant. Thus, we recommend you wait until late winter or very early spring to cut them down.

Should ornamental grasses be cut down in the fall or spring? ›

These grasses generally need warmth to grow (at least 20° C). So it is best to cut them back in late spring, after any threat of frost has passed, just as the new growth starts to show. Don't wait too long to do this to avoid cutting the tips of the new growth with the old.

How do you keep ornamental grasses looking good? ›

Ornamental grass is drought-resistant, so you don't have to water it much, and most pests don't find it appetizing. You only have to cut them back occasionally to eliminate the brown grass and keep it from dying. Additionally, you will have to divide it every few years.

What do I do if my ornamental grass is too big? ›

The ideal way to deal with grasses is to dig and divide them every few years while they're still in manageable-sized clumps. A good time to do this is early spring - after you've cut down last year's blades and just before new growth begins.

Can I divide ornamental grasses in autumn? ›

When to divide grasses. Cool climate grasses are best divided as they come into growth in late winter to early spring. Warm climate grasses don't come into growth until late spring, so are best not divided until late spring (May).

Do ornamental grasses multiply? ›

Unlike the tidy growth habit of clump-forming grasses, ornamental grasses that increase by rhizomes will spread, or run, throughout a garden bed and can quickly take over.

How do you prune evergreen ornamental grasses? ›

Q How do I prune evergreen grasses such as Stipa tenuissima? A These will struggle or even die if you cut them back to ground level in late winter with the deciduous grasses. Instead wait until April or May and gently comb through the plant with gloved hands to remove any loose old leaves and seed heads.

What fertilizer to use for ornamental grasses? ›

Best Fertilizer For Ornamental Grass

You can add compost each year around the base of the plant, especially one grown in a container. If you want to fertilize ornamental grass, use a balanced, slow-release fertilizer like Osmocote 14-14-14.

How late in the fall can you plant ornamental grasses? ›

You should try to complete fall planting during August and September. Then provide a light cover of straw or hay during the first winter for best results. Apply the mulch after several hard frosts. Plants should be planted no deeper than their previous growing depths and should be well watered after planting.

Should I cover ornamental grass in winter? ›

The point is, the clump style root systems of ornamental grasses are extremely hardy. So much so that they simply do not need any protection from their foliage on top to insulate them from the harsh conditions of winter.

Do you cut down purple fountain grass in the fall? ›

Fountain grass is a warm season grass that is dormant during the winter and begins growth after the coolest weather is past. You can trim the top any time from fall until growth resumes in the spring.

How do I know if my ornamental grass is cool season or warm season? ›

Many are semi-evergreen and never truly go dormant. Cool season grasses mature quickly and typically begin "flowering" in June, unlike warm season grasses that lay dormant (evidenced by ugly brown, straw-like blades) until late spring and then begin flowering mid to late summer.

Should evergreen ornamental grasses be cut back? ›

Generally, there is no need to prune evergreen grasses. If some light pruning is necessary to remove dead or damaged leaves, it is best to prune back only 1/3 to 1/2 of the plant in late February to early March.

When should evergreen grass be cut back? ›

Evergreen grasses
  1. Small evergreen grasses, such as Festuca glauca, can be trimmed in spring. ...
  2. Larger evergreen species such as Cortaderia selloana (pampas grass) benefit from hard annual pruning in early spring, cutting back as far as possible without damaging new growth.

Should fountain grass be cut back in winter? ›

Fountain grass is a warm season grass that is dormant during the winter and begins growth after the coolest weather is past. You can trim the top any time from fall until growth resumes in the spring. I enjoy the dormant grass through the winter, so I delay until just before growth begins.


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