Pruning should be carried out between April and the end of August, with up to three cuts during the growing season for Leyland cypress. Before pruning, check for bird nests, 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.

Formative pruning young hedges

• Year one: trim back the overlong sideshoots at the start of the growing season in April. Trim sides lightly in July and tie in the leader to a supporting cane as it grows. This will encourage dense growth
• Second year: trim sideshoots again to encourage further dense growth and leave a neat appearance over winter
• Subsequent years: continue trimming the sideshoots, but not the top of the tree, until the desired height is reached
• Once the desired height is reached:  in the following spring, shorten the leading shoots to 15cm (6in) below the required height. The new growth will make up the difference and form a thick top

Established pruning

• Trim the top and sides up to three times in the growing season (between April and the end of August)
• Shape the hedge to an inverted wedge – a flat-topped A-shape. By keeping a wide base, light reaches all parts of the hedge evenly and ensures the base does not become brown and bare

Pruning overgrown hedges

• With its rapid growth, a Leyland cypress hedge can soon become overgrown if not maintained at the desired height
• Healthy plants will usually respond well to reduction of up to one-third of the height. This is best carried out in early April as the new growth is about to begin
• Taking too much off the top can result in a bare, flat-topped hedge. Worse still, it may result in the death of older or less vigorous plants
• Where essential to reduce height by more than one third, it is possible (although not recommended) to reduce by one third in the first instance and then, when the plants have recovered, reduce the remaining plant by up to one half
• If reduction in width is required, care needs to be taken not to cut into older leafless growth as new growth will not appear from bare wood

High hedges

In recent years, ‘Leylandii’ or Leyland cypress has been highlighted in the papers as a ‘neighbourhood nuisance’. With little or no pruning, it can quickly grow to giant proportions and overshadow gardens. Legislation governing high hedges now gives people whose gardens are affected by tall hedges the opportunity to resolve the problem without involving lawyers.

The Anti-Social Behaviour Act 2003: Part 8 came into force on 1 June 2005 and gives people whose 'reasonable' enjoyment of their property is impaired by the close proximity of high hedges, the chance to alleviate the effects of overbearing living screens.

To avoid brown patches, hedge trimming should be carried out during the growing season and hedges should not be cut into older, leafless growth. Leyland cypress can cause skin irritations.

Infestations of cypress aphid can be very damaging, leading to extensive areas of brown.