Routine Trimming of Hedgerows
Trimming Hedgerows
- Cut hedgerows between 1st September and end February
- Side-trim to a triangular shape, leaving the peak as high as possible.
- Cut stems a little above the last cut, leaving about 0.5 cm of new growth.
- Leave mature trees and saplings, including thorns at irregular intervals
Healthy dense growth at the base of the hedgerow keeps it stockproof. Routine trimming is required to retain a dense base in a hedgerow and prevent hedgerow shrubs growing into mature trees.
Before trimming:
- Decide on reason for trimming
- Assess suitability for trimming
Timing
- Do not cut during the bird-nesting season
- With certain exemptions, the Irish Wildlife Act (1976, 2000) prohibits the cutting of hedgerow vegetation between 1st March and 31st August.
- Farms participating in REPS must not carry out hedgerow maintenance from end February to end of August.
Shape
- Side-trim to a triangular shape, sloping sides from a wide base. This prevents self-shading, allowing light to the base. Light encourages growth. This is important, particularly on north facing sides.
- Allow the peak as high as practical. The taller and bulkier the better for wildlife.
- Uneven, bushy topped hedgerows break up the wind and provide shelter. Neat, flat-topped hedgerows are not wildlife friendly.
- When cutting near the bank or base of hedgerows, avoid exposing bare soil. Bare soil erodes, roots are exposed or damaged and aggressive plant species can dominate.
Level of Cut
Cut stems a little above the last cut, leaving about 0.5 cm of new growth. When cut, dormant buds below the cut are stimulated to burst. Almost all new growth comes from within a few centimetres of the cut. This results in a dense mass of new shoots and a vigorous hedgerow.
Cutting back to the same level each time depletes the energy in the hedgerow. It uses its energy growing a small number of long shoots, rather than a dense mass of shoots. Repeated cutting at the same level forms scar tissue on the cut, discouraging new growth.
Cut stems a little above the last cut, which will be a few centimetres further out each time, resulting in a dense, vigorous hedgerow.
Trees
- Retain occasional mature trees and saplings, including thorns at irregular intervals. These flower, produce fruit, provide song-posts, vantage posts, nest and roosting sites for wildlife, which are absent in the body of a hedgerow.
- Topping a hedgerow containing thorny and smoothstem species favours the growth of the smoothstems. Consider removing unwanted trees at ground level. Trees such as sycamore, beech or chestnut, which cast a dense shade weaken hedgerows.
Machinery
A clean cut is required. Shattered or frayed branches can lead to decay and disease and reduce the vigour of the hedgerow.
- Sharp edges on cutting equipment are essential to give a clean cut.
- Appropriate machine for the job
- Finger bars: suited to regular trimming of soft, light material.
- Flail: suited to material up to 12 cms (0.5 inch), although capable of shattering much stronger stems, which is not desired.
- Circular saw: suited to re-shaping or coppicing.
Frequency
Cut hedgerows with a dense base in rotation around the farm approximately every three years. This always leaves some undisturbed for wildlife, preferably in different areas around the farm. A three year rotation may allow the flail to be used, depending on hedgerow growth.
Annual trimming may be necessary for safety reasons. Where it is necessary, avoid annual trimming of field sides of roadside hedgerows. Some stretches may also be left uncut.
Safety
Mechanical hedge trimming is dangerous. Ensure machinery and equipment are in safe working order. Consult operators’ manuals. Keep safety guards in place. Ensure operators are competent and work in a safe manner. Watch out for bystanders. Think safety and take action.
