Established hedges require trimming to keep them dense and compact. Formal hedges require more frequent trimming than informal hedges.
When to trim hedges
New hedges require formative pruning for their first couple of years after planting. Formative pruning is usually carried out in winter or spring.
After this, maintenance trimming is carried out, usually once a year for informal hedges and twice a year for formal hedges. Some formal hedges may need three cuts a year. Maintenance trimming is generally carried out between spring and summer.
See our advice in hedges: pruning times for more detailed information on timing.
Hand-held hedge shears are fine for smaller hedges, but for large hedges you'll probably find it easier to use an electric or petrol hedge trimmer. No matter what you use always make sure the equipment is sharp and well lubricated.
Always think of your safety when using a powered hedge trimmer. Wear safety goggles and sturdy gloves. Before starting, remove any obstacles on the ground. Avoid using powered tools above shoulder height and use sturdy step ladders or platforms, ensuring they are stable. Electric hedge trimmers are ideally used with a residual current device (RCD) and should not be used in damp conditions. Place the cable over your shoulder to prevent it being accidentally cut. See our advice in electricity in the garden for more safety tips.
There is no need for the width of even vigorous hedges to exceed 60cm (2ft) if they are regularly trimmed. Formal hedges should be slightly tapered on both sides so that the base is wider than the top and light can reach the bottom of the hedge. This is known as cutting the hedge to a batter.
Follow these tips to ensure an even, symmetrical hedge:
- Cutting straight, crisp edges by eye can be difficult. Use a taut horizontal string tied between two stout canes to act as a guide to cut the top of the hedge level. Canes or stakes pushed into the ground help with vertical lines
- To shape the top of the hedge (e.g. to an arch), cut a template of the shape required from cardboard or plywood. Place the template on the hedge and cut following the line of the template, moving it along as you proceed
- When using shears, ensure that the top of the hedge is cut level and flat by keeping the blades of the shears parallel to the line of the hedge
- When using a hedge trimmer, keep the blade parallel to the hedge and use a wide, sweeping action working from the bottom of the hedge upwards, so that the cut foliage falls away
Pruning an informal hedge is much like pruning normal shrubs. See the links below for more specific information on pruning shrubs;
Shrubs: pruning evergreens
Shrubs: pruning summer-flowering
Shrubs: pruning early-flowering
In general, when pruning informal hedges, remove misplaced shoots and cut back the hedge to its required size. Use secateurs or loppers where practical, especially if the hedge has large evergreen leaves, to avoid unsightly leaf damage.
How to trim hedges
Hedges can be divided into three groups:
Group 1 - Upright plants
For example: deciduous (hawthorn, privet); evergreen (box, Escallonia, Lonicera nitida)
- Cut back plants to 15-30cm (6in-1ft) on planting
- In summer trim side branches lightly to encourage bushing out
- In the second year (February to March) cut back growth by half
- Throughout the second summer trim side branches to maintain sides that taper towards the top
- In the second autumn cut the topmost branch (‘leading shoot’) to the desired hedge height
- Cut back all stems by one-third after planting
- Repeat this at the same time next year
Annually, during May to September, trim back the top and sides every four to six weeks to maintain the desired shape.
Group 2 – Stocky deciduous plants, naturally bushy at the base
For example: beech, hornbeam, hazel, Forsythia and Ribes sanguineum
- On planting, cut back leading shoots and side shoots by one-third, cutting to a well placed bud
- Repeat this in the second winter to prevent straggly growth and thicken up the hedge base
Trim annually in June (or after flowering) and again in August, clip to a shape that tapers at the top.
Group 3 - Conifers and most evergreens
For example: Lawson cypress, Leyland cypress, yew, bay, cherry laurel, cotoneaster and pyracantha
- On planting, leave the leading shoot unpruned, lightly cutting back any straggly side shoots
- In summer, trim sideshoots and tie in the leader to a supporting cane as it grows
- Use secateurs for broad-leaved evergreens (e.g. laurel and bay)
Clip to the desired shape one to three times during summer, until late August, when trimming should cease to reduce the risk of bare patches (see problems below). Use secateurs or hand shears for broad-leaved evergreens (e.g. laurel and bay). Stop the leading shoot at the desired height. Most conifers will not re-grow from old wood, so avoid hard pruning.
Informal and flowering hedges
Prune informal hedges where flowers are desired only once at the correct time of year to encourage flowering the following year. Pruning at the wrong time of year could remove the growth that will flower next year.
Prune those plants that flower on the current season's growth (e.g. Fuchsia) once in spring, as they will still be able to produce flowers that year.
Reduce the current season's growth by half in summer for plants that flower on one-year-old growth (e.g. Pittosporum).
In the case of shrubs that produce berries, such as Cotoneaster and Pyracantha, delay trimming until the berries disappear.
When undertaking work on garden hedges check that there are no birds nesting, as 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.
With conifer hedges, make sure you do not trim them after August, as this can encourage bare patches to develop in the hedge.