A brief history of urban hedging

Across urban landscapes, hedges provide people with privacy and a degree of insulation from the noise and pollution from traffic on the busy city roads. In an age where paving over front gardens to park cars has become the norm, it is to your credit if you are looking to increase the vegetation cover on your property or places where you work or study. But have you thought about what your choice of planting might mean for wildlife in the immediate area and across the wider landscape?

The Great North Wood project at London Wildlife Trust is now approaching the halfway point of its four-year duration, and much of the volunteer effort so far across 13 woodland sites in south London has been to remedy the effect of the 150-year-old gardening fashion for dense, exotic shrubbery that has gradually tightened its grip on the remaining fragments of this once wooded landscape (such as the example below of spotted laurel at Hillcrest Wood).

Plants such as cherry laurel, spotted laurel and rhododendron have been favoured since the 1800s for their dense, year-round cover. This is precisely why they are problematic for your local woodland. While evergreen vegetation, such as holly and yew, is an important component of British woodlands, the majority of canopy trees are deciduous (dropping their leaves in winter) and do not cast such an all-encompassing shade as these garden shrubs. Beneath a stand of cherry laurel, for example, (which also produces cyanide to suppress competitor plants), there is almost no other life. This means no young trees to replace the current canopy in the future, and no woodland wildflowers for you to enjoy either today or in the future. Where our volunteers have been clearing cherry laurel in remnants of the Great North Wood, there are already new oak seedlings popping up in the sunlight.

Planting for wildlife

Many introduced plant species delight gardeners without having impacts on the wider landscape, but some, such as cherry laurel, spotted laurel and rhododendron, do not recognise the boundaries of gardens and nature reserves (and why should they!). But this is not the only reason to think twice about using these species; the wildlife benefit of a monoculture laurel hedge pales in comparison to a native mixed hedge (see bottom of the page for more information).

Are you interested in creating a diverse, mixed hedgerow? The Great North Wood team recently teamed up with Lambeth Council to plant just that at Norwood Park and it is an example of a combination of species that you might like to investigate: hawthorn, blackthorn, hazel, guelder-rose, spindle, dog rose and field maple. Always bear in mind that lots of different species might be labelled with the same English name at a garden centre, so if in doubt look up the Latin names (see bottom of the page) to ensure you get what you want.

Or does your desired hedge need to provide some degree of security? The team have also just finished a project (pictured above) with the Dulwich Estate on Low Cross Wood Lane using mostly spiny species (hawthorn, blackthorn, dog rose) to deter vandalism on an exposed fence while also providing great benefit for wildlife on an area that was previously just mown amenity turf.

Perhaps your key concern is privacy and leaf-cover throughout the year. Then how about the example below from Forest Hill, a blend of holly and ivy. Female hollies produce bright red winter berries whilst ivy's flowers are a good source of autumn nectar for insects and its berries enjoyed by birds. And both plants take it in turns to nourish the caterpillars of the holly blue butterfly, with the first generation each year feeding on holly and the second using ivy.

So please do spread the word about planting hedges with wildlife in mind. The choices of species made by individuals, maintenance teams and housing developers will continue to be detrimental to local woodlands if we continue as we have done for the past two centuries, but if chosen well they can have an array of positive impacts for local wildlife and provide changes and interest reflecting the seasons throughout the year.  

Species mix in new hedges planted by London Wildlife Trust at Norwood Park
 

Hawthorn (Crataegus monogyna) 40% - Often the principal component of traditional hedges because its spines stopped animals from passing through. Its armaments have the benefit of protecting nesting birds (such as the wren pictured at the top of this blog).
Blackthorn (Prunus spinosa) 20% - One of the first shrubs to burst into flower in the spring, benefitting nectar-feeding insects, the flowers are followed by its berries (sloes) that can be used to flavour gin.
Hazel (Corylus avellana) 10 % - Its leaves support caterpillars of a number of moths including the barred umber and nut-tree tussock.
Guelder rose (Viburnum opulus) 10% - Confusingly not an actual rose, producing clusters of white flowers which are particularly attractive to hoverflies.
Spindle (Euonymus europaea) 10% - It has gorgeous berries, but can attract birds looking for aphids on its leaves.
Field maple (Acer campestre) 5% - Its craggy bark provides habitat for insects.
Dog rose (Rosa canina) 5% - Known for its flowers and spines, but leaf-cutter bees make particular use of its leaves.