A living fence with a job to do

Oxfordshire's hedgerows are some of the county's most overlooked wildlife habitat. Along the clay vales, up onto the chalk of the Chilterns and through the old enclosure landscapes around Otmoor and the Cherwell, these thin strips of thorn and hazel do far more work than most of us give them credit for. They shelter nesting birds, feed insects through the spring and summer, hold berries into the depths of winter and act as corridors that let wildlife move between woods, meadows and gardens without crossing open ground.

The good news is that hedgerows respond quickly to a change of management. A hedge that has been flailed to the same height every autumn for twenty years can be brought back to life within two or three seasons. It usually costs less time, not more.

Cut less often: the single biggest favour you can do

Annual trimming is the main reason so many hedges are wildlife-poor. A tidy, box-shaped hedge cut every year rarely flowers well, carries almost no berries and offers little in the way of dense, sheltered structure. Traditional boundaries were often cut on a rotation of eight to fifteen years, and many were laid rather than trimmed.

Aim for a three-year rotation, cutting a different section or side each year. If you must cut the whole length, cut late — late January or February — after the berries have been stripped by redwings, fieldfares and blackbirds. Avoid cutting between March and August, when nests are active; in England it is an offence to damage or destroy a nest in use, and the practical window for hedgerow cutting closes at the end of February anyway.

• Leave at least one stretch uncut each year so there is always fruit and blossom somewhere along the line.
• Raise the cutter bar so you are trimming the top and one side, not scalping the whole profile.
• Vary the height between sections — an uneven hedge is a richer hedge.

Shape, height and a dense base

Think of a good wildlife hedge in cross-section: roughly an A-frame, 2 to 3 metres tall, 1.5 to 2 metres wide at the base, tapering inwards. That shape lets light reach the ground so the hedge keeps growth low down, while the wide base gives birds and small mammals cover to move along it unseen.

A hedge with a bare, leggy bottom and a thin top is the classic flail-damage silhouette. If yours looks like that, several years of gentler cutting will help it thicken. Where there are gaps, plant up with native whips — hawthorn, blackthorn, hazel, field maple and dog rose — and protect them with a spiral guard or a small cage for the first few years. Laying a hedge, or asking a local hedge-laying group for advice, rejuventates old stems and lets light back to the base, though it is best done on a stretch at a time rather than the whole boundary at once.

Bloom in sequence, berries for winter

Different shrubs feed different creatures at different times, so variety matters more than sheer volume. A mixed hedge gives insects a long season of nectar and pollen and gives birds a long season of fruit.

• Blackthorn flowers in March, often before the leaves, and is one of the earliest nectar sources for queen bumblebees.
• Hawthorn follows in May, with haws in autumn that hungry thrushes rely on.
• Dog rose, bramble and honeysuckle flower through summer, feeding bees, hoverflies and moths.
• Ivy is the unsung hero: its late flowers are a lifeline for hoverflies, wasps and red admiral butterflies in October, and its berries ripen in late winter when little else is available.
• Hazel, field maple, spindle and guelder rose add structure, autumn colour and further fruit.

Try to keep a few brambles and a patch of ivy. They look scruffy, but they are among the most productive plants in the whole hedge.

The ground beneath: margins, tussocks and dead wood

What happens at the foot of the hedge matters almost as much as the hedge itself. A strip of rough, tussocky grass a metre or two wide, topped only every few years, gives cover for hedgehogs, voles and beetles, and provides the nesting habitat that yellowhammers and whitethroats need. Nettles left to grow in a sunny patch are the food plant for the caterpillars of peacock, small tortoiseshell and red admiral butterflies.

Keep fertiliser, slurry and herbicide drift out of the hedge base and margin; nutrient-boosted grass grows rank and smothers the wildflowers. Leave dead wood and old stems lying at the foot of the hedge, and never flail right down to the soil. Beetles, fungi and overwintering insects all depend on that litter layer.

Signs you are getting it right

Within a season or two you should notice more of the small, quiet things. Listen for the scratchy song of a whitethroat from the top of the hedge in May, or the soft "tick" of a dunnock working the base. Watch for yellowhammers perched on the outer twigs, linnets dropping into the margin to feed, and bullfinches taking buds in late winter. In some parts of the county, hazel dormice use hedgerows to move between woods, so a well-connected line of mixed shrubs is worth more than its length suggests.

Ancient hedges are easy to spot and worth protecting: a bank and ditch, a mix of shrub species, and woodland flowers such as primrose, dog's mercury or bluebell along the base all suggest a boundary that has been there for centuries. Manage it gently, cut it less, leave the berries standing, and it will keep giving back for decades.