How to prune hedges

Why and when to prune hedges

A well-maintained hedge provides a good, smart boundary to a garden, but if left unchecked, a hedge can soon lose its shape and end up casting unwanted shade. With a good pruning schedule you can keep hedges under control without too much effort.

Most evergreen formal hedges like to be trimmed two or three times a year, while they're actively growing. Conifer hedges such as leylandii need regular pruning or these fast-growers will soon outgrow their location.

Pruning informal hedges depends on when they flower. Lavender, fuchsia, roses and other plants that flower on the current year's wood are best pruned in early to mid-spring, while those that flower on old wood, such as forsythia, deutzia and berberis, should be pruned when the blooms fade.

Choosing tools

• Hand shears are fine for short runs, but if it's a long hedge, invest in an electric, battery or petrol-powered hedge trimmer. It will make light work of the job and won't leave you with tired arms.
• Keep hand shears sharpened and let the tool do the job it was designed for, rather than trying to hack away with blunt blades.
• If you use an electric trimmer, make sure it's plugged into a safety socket fitted with a residual current device or circuit breaker, so that the engine will cut out if there's an accident.
• When trimming keep the cable away from the blade, ideally draped over one shoulder rather than trailing on the ground.
• Wear appropriate protective equipment such as goggles and gloves.

Choosing the right method

Formal hedges

• Start by pruning the top flat.
• If the hedge isn't too long, you should be able to cut by eye, stepping back occasionally to check your progress.
• If you don't trust your eye, hammer two stakes into the ground and stretch a length of string between them to use as a cutting guide.
• Next, cut the sides, making the top narrower than the base.
• Brush off trimmings from the top of hedge and from the base of the hedge to prevent the spread of fungal diseases.

Informal hedges

• Although flowering, informal hedges are allowed to grow naturally so that their shape isn't spoilt, that doesn't mean they never have to be pruned.
• If neglected they could soon grow too tall or spread out of their allotted space.
• To keep them in good shape, occasionally remove old stems with secateurs or cut branches to keep within bounds.

Dwarf hedges

• Low growing hedges used for parterres, knot gardens or as borders around vegetable beds can be kept neat by trimming twice a year.
• Cut box, rosemary, lonicera, lavender and germander in spring and then in mid-summer.
• Use string stretched between two stakes to ensure the top is flat and then cut the sides vertically.

Aftercare

• Once your hedge is trimmed to the desired shape, water and mulch the plants to keep them in good condition.
• Occasionally a hedge plant can die or become damaged through disease: if it's not possible to save the plant, wait until autumn and replace it.
• Tip: Keep flowering hedges in good shape by occasionally removing old branches and taking off growth to keep them within bounds.

Hedging plants to try

Flowering

• Forsythia - brilliant yellow flowers in spring
• Berberis - dense, thorny and tough hedge, with flowers in spring and berries in autumn
• Deutzia - ornamental white or pink flowers
• Lavender- fragrant low borders

Evergreen

• Box - classic topiary hedging
• Privet - hardwearing, moderately fast-growing hedge
• Cherry Laurel - up to 6m high with glossy leaves
• Conifers - match the variety you choose with the height of the hedge you want