How to trim a hedge
Regularly trimming a hedge controls its size and keeps the growth dense, providing a wildlife friendly boundary to your garden.
- Trimming is a form of light pruning, generally only removing growth less than a year old
- Formal hedges need trimming up to three times a year to keep them neat
- Some deciduous hedges, such as hornbeam and beech, don’t drop leaves from young growth in autumn, thereby providing screening year round
- Regularly trimming boundary hedges improves their ability to capture pollution and block traffic noise
Hand shears are suitable for trimming small hedges and soft growth, but for large hedges it’s easier to use an electric, petrol or cordless battery powered hedge trimmer. Large-leaved evergreen hedges are best cut with secateurs or loppers if you have the time, as using hand shears or hedge trimmers creates cut leaf surfaces that look unsightly. No matter what you use, make sure your equipment is in good working order and the blades are sharp.
Always think of your safety when using a powered hedge trimmer. Wear safety goggles and thick gloves. See our guides to using electricity in the garden and gardening safely for more safety tips.
When using a step ladder, tripod ladder or platform, ensure they are sturdy and stable. Tripod ladders with adjustable legs are useful when working from uneven ground. Aim to keep hedges at a height and width that can be safely maintained. If your hedge hasn’t been regularly trimmed and the size needs to be reduced significantly, see our guide to renovating hedges for advice on tackling it.
Before starting to trim, check the hedge thoroughly for birds’ nests. The main nesting season in the UK is from early March to early August, but it can go on for longer. It is an offence under the Wildlife & Countryside Act 1981 to damage or destroy the nest of any wild bird while it is in use or being built. So, if you find an active nest, delay trimming until you are sure the young birds have fledged.
What you’ll need to trim a hedge:
- Hand shears or powered hedge trimmer
- Residual current device (RCD) for electric trimmers
- Secateurs or loppers (useful for cutting thick or low growth and large-leaved evergreen hedges)
- Sturdy boots and thick gloves
- Safety goggles
- Ear defenders (optional)
- Canes and string
- Rake or broom
- Tarpaulin, an old sheet or blanket for collecting trimmings (optional)
Keeping the width of your hedge narrower at the top than at the base allows light to reach the lower branches. It also prevents heavy loads of snow sitting on top of the hedge, which can splay and damage branches.
How to trim a hedge in six simple steps
Assess your hedge
Walk along the length of your hedge and check the sides to see if growth rates differ. A trim should remove nearly all the young (less than a year old) growth, but if you want straight sides, you may need to leave some sections longer if growth rates aren’t uniform. Following a straight edge along a lawn or paving, or setting up a string line at ground level, will serve as a useful guide.
Prepare for trimming
Remove any obstacles under and around the hedge and lay a length of material on the floor to collect trimmings. This makes the task of clearing up much easier, as the trimmings can simply be bundled up in the material and removed.
If you are using a corded electric hedge trimmer, make sure it is plugged into a residual current device (RCD) before you start trimming.
Cut the sides first
Start trimming at the bottom and work upwards, keeping the blades parallel to the side of the hedge. If using a hedge trimmer, cut in arcs from the bottom up.
If trimming a low hedge, less than about 1m (40in) in height, aim for vertical sides. Taper taller hedges to make them slightly narrower at the top, or have a ‘chamfer’ – a section towards the top of a vertical side that slopes at a 45° angle to meet the horizontal top.
Don’t allow hedges to become wider at the top than they are at the base, as this will prevent light reaching lower sections, causing poor growth and bare patches.
Use a string line to get a neat top
For a straight top, tie string about 1cm (½in) below your desired height to canes or stakes at either end of the hedge.
If your hedge runs along sloping ground, decide whether it would look better to slope the top of the hedge parallel with the ground, have a level top with occasional steps down, or to allow hedging plants at the bottom of the slope to remain taller to keep the height of the hedge level.
You may prefer an undulating or more creative top on your hedge. To maintain the lines, look at where the previous pruning cuts are and trim to leave about 1cm (½in) of new growth.
Regularly check your progress
Whether you are using hand shears or a hedge trimmer, regularly take a moment to assess your progress. Check the sides by looking along the length from the end where you started cutting. Stand back some distance to check the top.
If you are new to hedge trimming, it is best to trim lightly at first, then check the shape and take more off if needed. This is particularly advisable when cutting most conifer hedges, as they don’t regrow from old wood.
Clear away trimmings
Rake clippings off the top of your hedge so light can reach the cut stems and encourage good regrowth. Bundle up clippings collected in the length of material you laid earlier, and rake or sweep up others on the ground. Add the clippings to your compost bin, ideally in layers between other material, or add to your council green waste recycling bin. See our guide to dealing with garden waste for other ways to reuse or remove the clippings.
If your soil is light and sandy, or the hedge has shown signs of nutrient deficiency, apply a general-purpose granular fertiliser just before mulching. During drought conditions, hedges will benefit from additional watering.
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.