8 March 2002

IMPROVING

YOUR HEDGE PLANTING

The Countryside Stewardship Scheme has provided a

welcome boost for the planting and maintenance of

hedgerows. Antony Strawson, of woodland management

specialists Eamonn Wall & Co, highlights key aspects of

hedgerow planting, establishment and maintenance

History

ITS reckoned that one-fifth of Britains 500,000 miles of hedgerow were removed between the early 1960s and the mid-1980s. Some was grubbed out as farmers amalgamated small fields to form larger ones, some went as hedges deteriorated and were replaced with fences. Other stretches were lost as roads were widened. Whatever the reason, hedgerow removal attracted widespread criticism from the public and environmental bodies alike.

In the last few years there has been a net increase in UK hedgerow planting, considerably boosted by the arrival of grants through the DEFRA-administered Countryside Stewardship Scheme (CSS). This discretionary scheme is based on a 10-year whole-farm conservation plan, providing funding for a wide range of conservation projects including hedgerow planting and management. Grants of up to £3/m are available for new planting, with additional supplements of up to £1/m for preparatory works such as the removal of old fencing.

Design, location and purpose

As with all tree planting, establishing new hedges requires careful planning.

Points to consider include the design, location and purpose of the hedge and the effect it will have on the long-term management of the farm.

Choose species that will achieve the above and suit your location and soil type. For most stockproof and conservation hedges, hawthorn and blackthorn should form the backbone of any species mix because both are suited to a wide range of soil conditions and grow vigorously to produce a dense, thorny barrier.

But remember to include other native species like field maple, dog rose, hazel, crab apple, guelder rose and wild privet to give visual diversity and a wider range of food and habitats for wildlife. Under the terms of the CSS, at least four species are required with no one species comprising more than 75% of the total number. Where appropriate, you could also include locally native tree species like oak, ash, beech, birch, lime, chestnut which are suitable as individual hedgerow trees.

Spacings

Normal practice is to plant two staggered rows, 30cm between them and no more than 50cm between the plants along the rows (4-8 plants/m). Plant the minor species first in random groups occupying 1-2m and then put in the main species of, say, hawthorn that would account for 70-75% of the hedge.

Plant sizes? Traditionally you would use one-year-old plants of about 20-40cm in height, though where weed competition will be strong you may prefer two-year-old 40-60cm plants. Individual hedgerow trees need to be 60-90cm high to help them grow and keep them above the general height of the hedge. They are often planted in taller guards so the hedge-trimmer driver can spot them.

Protection

You will need to protect newly-planted hedges against browsing by rabbits and hares and grazing by livestock.

Individual guards such as spirals, tubes or sleeves are a cheap means of protection and they also provide a favourable growing environment and make applying herbicides much simpler. However, they often produce leggy plants with few branches at ground level and often need removing.

Where there are livestock, erect a stock fence at least 1m away on either side. Alternatively, enclose the new hedge within a rabbit fence. This protects against browsing damage but is more expensive.

Because weed competition can kill young hedging plants or slow their growth rates, the correct time to decide on a control strategy is in the summer before planting.

Pre-planting control

This can serve two purposes – removing thick weed growth (especially dense grass swards) makes planting easier and killing weed cover reduces competition during the early part of the first growing season.

Mowing or strimming before planting will serve the first purpose but you will usually need to control the weeds remaining. You can do this at the pre-planting stage by a 1m-wide strip application of a broad range contact herbicide such as glyphosate.

Ploughing will create an ideal planting site, which is likely to be weed-free well into the first growing season. However, it will also be an ideal seed-bed for thistles, nettles and other broadleaves weeds that can cause problems later.

Post-planting control

Once the hedge is planted, controlling weeds by strimming or mowing them can have little effect. It may even make matters worse by stimulating them to grow faster and compete more vigorously.

Physical ways of suppressing weeds like mulch mats and bark chip mulch are generally very expensive. Mulch mats can blow away on exposed sites and weeds may grow through the slits cut in the mat for the trees. On some sites, plastic mulch mat in continuous rolls with the trees planted through can be successful but they usually require eventual removal and can harbour voles who strip bark off the hedge plants.

Individual guards allow a broad range of contact herbicides to be applied along the hedgerow with minimal risk of damage. However where the hedge is unprotected, chemical weed control is made more difficult.

Herbicides approved for use on broadleaved trees and hedges cannot generally be applied directly over the young plants in the summer when they are in leaf. So ideally an appropriate herbicide with residual action should be applied along the hedgeline in the winter.

Each herbicide has its own range of susceptible target weeds but the herbicides used most frequently for winter applications are Kerb granules or Kerb flo (propyzamide), which control a wide range of grasses, Stomp (pendimethalin), which controls a range of annual grasses and some broadleaved weeds including cleavers. Stomp can be applied in a tank mix with Kerb flo.

Flowable Atrazine (atrazine) is also used widely. This controls a range of grasses and some broadleaved weeds, but it should never be applied near to water or where run-off could occur.

As with all chemicals take time to study its label and consult a BASIS-registered professional if you are in any doubt.

Sterile strip

During the first three to five growing seasons after planting, further control may be required in the summer to deal with weed species not affected by the previous winters herbicide application or by re-invading weeds.

There is often little option but to apply a contact herbicide as a strip along each side of the hedge, taking care not to let the chemical come into contact with the hedging plants themselves. Hawthorn is particularity sensitive to damage by herbicides, especially glyphosate. This may leave weeds such as thistles, nettles and willowherb in among the hedge and if these need to be removed the only option is to pull them out by hand.

Long-term management

The long-term management of hedges depends on whether they are treated as shelterbelts (and allowed to grow freely) or as traditional tightly-cut hedgerows. If the latter is the case, the most environmentally-friendly trimming policy is to cut every third year or longer so that there are flowers for the pollinators followed by berries and seeds for the birds.

An A shape is best for wildlife; make it 1.5-1.8m (5-6ft) high and 2.4m (8ft) through the bottom. Dont cut during the nesting season from April to July.

Hedges provide many benefits and with careful planning their establishment can be fairly straightforward. New planting combined with the restoration of old hedgerows by coppicing or laying can greatly increase the amenity, wildlife and conservation value of a property. Might we one day see the hedgerow statistics quoted in the press acknowledge the degree of new hedge planting and restoration taking place in the countryside?

Antony Strawson is a consultant with the tree and woodland management business of Eamonn Wall and Co (01777-702930).