Hedges: renovation

Hedges can quickly become overgrown, filling up a border and becoming difficult to maintain. Renovation may rejuvenate an old hedge. With legislation in place concerning the height of evergreen hedges, renovation may be advisable where hedges have got out of hand.

Hedge Renovation. Credit: RHS/John Trenholm

Quick facts

Suitable for Overgrown hedges
Timing Mid-winter (deciduous); mid-spring (evergreen)
Difficulty Easy to moderate

Suitable for...

Many hedges respond well to renovation, including beech, box, hawthorn, holly, hornbeam, Lonicera nitida and yew. These can all be reduced by as much as 50 percent in height and width in a single cut. More drastic renovation should be carried out gradually.

Most conifers (apart from yew) do not respond well to renovation, as they do not re-shoot from old wood. Conifer hedges require regular light trimming. If they have become overgrown, then a method for partial renovation is given below.

When to renovate hedges

Deciduous hedges should be renovated in midwinter, when they are dormant and leafless.

Evergreen hedges should be renovated in mid-spring, as they respond better to pruning when in active growth and the risk of frost has passed.

How to renovate hedges

Before undertaking work on hedges, check that there are no nesting birds in the hedge, 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.

Where drastic renovation is necessary (i.e. more than one-third reduction in height or width), it is better to stage this gradually over two or three years.

Year 1

  • Cut back the width on one side of the hedge only
  • Cut to at least 15cm (6in) less than the desired width, or almost to the main stems if necessary
  • Remember to cut the hedge to a 'batter' (sloping sides), so it tapers from the bottom to a thinner top, allowing light to reach the bottom of the hedge
  • Trim the other side of the hedge as usual
  • Leave the height unaltered
  • Mulch and feed in spring to encourage vigorous re-growth
  • Allow a full growing season for recovery
  • Water well in dry spells in the first growing season following renovation

Year 2

  • Cut back the other side of the hedge, cutting almost to the main stems, if necessary. Cut to a similar batter as the previous side
  • Leave the height unaltered
  • Mulch and feed in spring to encourage vigorous re-growth
  • Allow a full growing season for recovery
  • Water well in dry spells in the first growing season following renovation

Year 3

  • Cut back the height of the hedge to at least 15cm (6in) below the desired height
  • Cut back harder where the upper portions of the hedge are open and patchy 
  • Mulch and feed in spring to encourage vigorous re-growth
  • Allow a full growing season for recovery
  • Water well in dry spells in the first growing season following renovation

Conifer hedges

These cannot be renovated in the same way as deciduous and evergreen hedges. Most conifers (with the exception of yew) will not re-shoot from old wood.

Examples of conifer hedges intolerant of hard pruning include Cupressus, Chamaecyparis and × Cuprocyparis leylandii (Leyland cypress).

When a conifer hedge has become too large, there are some steps that you can take to reduce its impact without complete renovation:

  • Reduce the height by up to one-third in April
  • Thin out the side branches, removing selected branches right back to the trunk but leaving the others intact. This will allow more light and air into the area around the hedge
  • Mulch and feed in spring to encourage vigorous re-growth
  • Allow at least a full growing season for recovery
  • Water well in dry spells in the first growing season following renovation

Hedges reduced in height by more than one-third may not fill out, remaining flat and bare at the top.

Problems

Renovation pruning inevitably results in ugly bare patches, but re-growth should be sufficiently rapid to hide these within one or two growing seasons.

Where holes or bare patches have developed in conifer hedges intolerant of renovation, it may be possible to tie in a new branch to that bare area in order to cover it.

Brown patches can be a problem in some species of conifer hedge for one or more reasons. Environmental factors, pruning at an inappropriate time of year, aphids or fungal diseases may be to blame.

When reducing the height of a long hedge, it can be difficult to get a straight line along the top. Painting an indicator line of whitewash along the hedge just above the point of cutting may help. Alternatively, set up a string line along the hedge to act as a cutting guide.

If recovery seems poor after the first or second stage of renovation, delay the next stage for a further year to give the hedge time to re-shoot.

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  • Pippa-Jane avatar

    By Pippa-Jane on 24/06/2014

    Hi, I need a bit of advice - I have a evergreen broad leaved hedge around 2 sides of my property which is about 7-8 feet high. I don't know what plants make up the hedge, but I think there are 2 different kinds. I am building a new house and the drain-layers and electricity company need to dig 2 trenches in 2 different places through the hedge. I would like to regenerate the hedge across the gaps but am not sure how to do this! Any advice would be great! thanks

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