There are simple steps that can be taken on farms to improve the condition of hedgerows for pollinators and wildlife, an environmental farm adviser has said.

The open period for cutting hedgerows in NI is just over two weeks away and runs from 1 September to 28 February.

“The later in the season you leave it the better. It gives more chance for the berries to stay on the hedge and for birds to access the crop,” said Peter Gallagher from Ulster Wildlife.

Whilst roadside hedges may need cutting regularly for safety reasons, the advice from an environmental perspective is not to cut hedgerows that run between fields every year.

Limit flailing Gallagher explained that flower buds usually only form and produce fruit in their second year of growth, so annual flailing limits how much food is available.

Rather than cutting all hedgerows once every two or three years, it is best practice to cut hedgerows in a rotation with half or a third of the farm cut annually. This means there should be flowers for pollinators and berries available for wildlife every year on the farm.

Hedge cutters should be kept sharp to ensure a clean cut and the best possible regrowth. Care should also be taken to lift flail cutters when young trees approach so that they get a chance to develop.

Aside from restricting buds and fruit, Gallagher said flailing a hedgerow too often can affect the overall shape of the hedge and limits its ability to grow out.

Allowing for regrowth

“Box hedges that are growing on stilts provide very little cover or shelter either for wildlife or for farm animals laying behind them in the spring or autumn time,” he said.

“You should be allowing a bit of regrowth every year. You should be coming up four to six inches every time you cut a hedge, to stop all the knuckling in the one point,” he added.

Small increases in the cutting height will help keep the hedgerow dense and stop it from losing shape.

If done properly, it should mean there is little risk of the hedgerow getting too tall. For example, raising the cutting height by four inches every two years means it will take 20 years for the hedge to gain one metre in height.

The ideal hedge is an “A” shape with a thick, dense base that gets narrower towards the top. This lets light reach the plants at the base of the hedge and gives protection for wildlife.

Under current land eligibility rules, hedgerows can be up to four metres wide (two metres from the centre) to remain eligible for the Basic Payment Scheme. If it exceeds four metres wide, then the entire hedgerow is ineligible for payment.

However, the rules are set to change in 2026 when all land, regardless of its environmental and agricultural condition, will be eligible for the new Farm Sustainability Payment.

There is a long list of different plants present at the base of an old hedge on Trevor’s Irwin's farm which dates back to the 1840s.

Old hedgerows are best for biodiversity

Old hedgerows contain a much wider range of plant species than newly planted hedges.

A clear example of this is seen on Trevor Irwin’s farm in Boho, Co Fermanagh.

He has various stretches of well-managed hedgerows which have all been planted within the past 25 years under agri environment schemes.

Numerous plants

However, he also has an old hedgerow that historic farm maps suggest was present in the 1840s.

Peter Gallagher from Ulster Wildlife listed numerous plants at the base of the old hedge on Trevor’s farm. This includes primrose, herb robert, ivy, holly, wild strawberry, rose hip and germander speedwell.

Peter Gallagher from Ulster Wildlife and Trevor Irwin from Boho, Co Fermanagh.

“This will support a massive number of pollinators in the springtime. No matter how long a new hedgerow is established, I don’t think we will ever get it to this level of biodiversity,” he maintained.

“It’s very clear that old hedges will outperform new hedges in terms of the different plants they support. That’s why carefully managing existing hedgerows is so important,” Gallagher said.

Hedge laying involves partially cutting each stem close to the ground.

Environmental farm advisers often recommend using hedge-laying techniques when it comes to managing hedgerow habitat.

This usually involves having minimal flailing and letting the hedgerow grow out. When it is around 3m or 4m high, each stem is partially cut close to the ground.

Ulster Wildlife’s Peter Gallagher explained that cutting should be done delicately, usually with a short billhook, or a chainsaw can be used for thicker stems. Each plant should effectively bend over with its own weight as it is gradually cut. Plants should not be pulled to the ground with too much force as this can cause the stem to split or break off completely.

Stock proof hedges

Gallagher said it is important to trim off any heavier branches at the top of each plant before it is cut, so it is easier handled and is not too bulky when it is laid on the ground. Afterwards, stakes can be put into the ground to hold the laid plants in place.

On Trevor Irwin’s farm in Boho, a 20-year-old hedgerow was laid last winter and is growing well now.

There are leaves and fruit throughout the hedge and new shoots are growing upwards at the point where the stems were partially cut.

One side of a double fence was removed before the work started but the fence did not have to go back up afterwards as the laid hedge was stock proof.

The hedge laying process is labour intensive, but Gallagher said it often leads to better outcomes than other hedge management approaches, such as coppicing, which involves completely cutting off each stem at the ground.

“Many people see hedge laying as the ultimate management technique. You keep the existing plants, the hedge remains stock proof and you also maintain berries for birds to feed on the following season,” Gallagher said.