Hedges, walls or fences may be needed for security, marking ownership of the site, or dividing areas within it. Ditches or barriers against vehicles may also be needed at the perimeter of the site. Hedges, walls, fences and ditches can all add habitat diversity to a site, without affecting its overall natural development. Creating and maintaining boundary features are suitable projects for groups of volunteers, and can include skills training.
Hedges, walls and fences have the disadvantage that anti- social behaviour can be hidden behind them, out of view from nearby housing and roads. The use and enjoyment of the site may be increased by opening it up and increasing views through it, and from the outside in.
The traditional method of managing hedges in farmland evolved as a method of producing stock-proof barriers from native species of tree. Tree species were selected which produced thick or thorny growth when trimmed or lightly browsed by stock, and which if left to grow, could be partially cut through and laid horizontally to form a barrier, and would then resprout from the base. Some hedges were also managed by coppicing or pollarding. As well as stock control and shelter, hedges provided fruit, nuts, fuel and poles for various purposes.
Hedges of hawthorn, blackthorn, beech, hornbeam and other species can be maintained for many years by regular trimming, and if kept to a rounded or ‘topped A’ shape can remain stockproof. A height of 1.2-1.8m is needed for safe nesting sites for birds. Trimmed hedges come into leaf earlier in the season than the same species in woodland. The common hedging species of hawthorn and blackthorn are anyway early-leafing species, so hedges provide a valuable early season food source for invertebrates, and their predators. The bottoms of dense trimmed hedges are an invaluable habitat for invertebrates, small mammals, reptiles and other creatures, providing a reserve of untrampled, undisturbed habitat, with rotting leaves, dead wood, and crevices in roots and banks.
See Hedge Types diagram below.
Hedges and other boundaries in urban areas rarely need to be stockproof, but being a deterrent to dogs and people may be a useful quality. Planting a hedge with the aim of letting it grow into an informal hedge for future laying may not be appropriate, especially on small, isolated sites. There may not physically be room for the hedge to grow sufficiently tall, and during this phase the dense undisturbed habitat at the bottom may be lost. The physical changes through the life of a laid hedge may also be rather drastic for wildlife, where there is not sufficient length to maintain a rotation of hedge habitats.
Hedges on small urban sites, whether of native or introduced species are best managed as linear thickets or garden hedges. Informal hedges can be planted, of species which tend to grow naturally as multi-stemmed shrubs, but depending on management and use, may not develop the thicket-like growth and undisturbed base of a trimmed or laid hedge. On larger sites, hedges can be grown and laid in the traditional way, or managed by coppicing or pollarding.
Native species for trimmed hedges
Hawthorn, beech, hornbeam, field maple, elm and holly all respond well to trimming and make dense growth. They can be grown singly or mixed in a hedge. Holly is best trimmed annually, but other species can be left for 2 or 3 years, and then cut hard back as necessary. Beech and hornbeam, although deciduous, retain their leaves through the winter. Guelder rose, dog rose, wild privet and gorse can also be mixed in. Blackthorn makes a spiny stockproof and vandalproof hedge if trimmed frequently, but produces suckers which may be a problem. Bramble, ivy and clematis are likely to appear, or can be transplanted if desired. They may need keeping in check to prevent them suppressing other species.
Native species for laying
Species which have plenty of bushy growth that holds in place when laid are preferred, together with thorns to deter stock and people. Stems that are supple and easy to cut are also a useful quality. Hawthorn is easily the best, having these qualities, plus being very hardy and tolerant of different soils, quick growing and easy to propagate. It is the main constituent of most hedge planting schemes. Blackthorn is bushy and thorny, cuts and lays easily, but tends to sucker into adjoining land which may be a disadvantage.
Smoothwood species such as ash, beech, oak, elm, hornbeam, field maple, hazel, willow, sweet chestnut and alder can be laid, but produce rather open growth. These species can also either be coppiced at ground level, or pollarded at hedge-top level.
Native shrubs for informal hedges
Holly, crab apple, box, dogwood, elder, wild privet, spindle, guelder rose and wayfaring tree are suitable for informal hedges or narrow copses. If they are to develop into a useful habitat, sufficient width must be allowed for the shrubs to grow naturally. At least 3m width will normally be necessary, making a narrow woodland feature rather than a hedge.
note that where hedges are being grant-aided, the choice and proportion of species in the hedge will have to be agreed with the grant-aiding authority, as will the planting distances, fencing or other protection, mulching and aftercare.
There are many species and varieties of introduced shrubs which can be used for ornamental or fruiting hedges. Any good gardening reference book will give details.
Pioneer tree and shrub species of poor, stony soils, such as the native birch and sallow, and the introduced buddleia and cotoneaster, spread naturally by seed onto urban wasteland sites. By their nature they are mostly open growing and light demanding and do not respond well to close planting, trimming or laying. Other species which spread in by suckering from the edges of the site, from dumped garden rubbish or from abandoned gardens are more likely to be suitable hedging species. It may be possible to incorporate existing clumps into new hedges, or to transplant small clumps or self-seeded plants to make an informal hedge of the characteristic local urban species. They will also provide a free source of plants. Cotoneaster, buddleia, berberis and laurel are possible candidates from the naturalised urban flora.
Obtaining hedge plants.
Hawthorn and other species for hedging are widely available from nurseries, and can be obtained by mail order for planting during the winter. Hedging shrubs include hawthorn, blackthorn, guelder rose, wild cherry, hazel, wild privet, field maple, elder and crab apple. The hedge can be left to grow for laying, trimmed regularly, or grown as an informal hedge.
Some individuals and interest groups are keen on retaining local genotypes of plant species. Planting hedges grown from local seed, or propagated vegetatively, is a way of doing this. Individual plants within hedges that are going to be trimmed or laid have potentially a very long life, possibly longer than individuals in woodlands. The seeds or cuttings need to be gathered from an existing hedge, woodland or individual tree that is itself of semi- natural origin. The hawthorn hedges planted during the enclosure movement of the 1800s were from nursery-grown stock, although earlier enclosure hedges may have been grown from locally gathered seed. The best sources are likely to be from long-existing commons or semi-natural woodlands, the relict patches of copse left isolated by development, native species growing in churchyards or hedges of known ancient origin.
Abandoned fertile land such as allotments or farmland may become colonised with species such as hawthorn, blackthorn, ash and oak, rather than the typical pioneer species of poor soils. Where permission can be obtained, these could provide a source of native hedging plants, which although of unknown provenance, will at least be known to be successfully adapted to local conditions. Transplant seedlings or small plants in winter.
Planning and planting a new hedge
Choose the species which are appropriate to the type of hedge you want to create (see above), and which suit the soil and locality. Any existing vegetation on the site, and nearby woods or hedges will be a guide.
To be a useful habitat and a barrier, most hedging plants need planting in a double staggered row. The distance depends on how dense the growth needs to be, and whether the hedge is to be trimmed or laid. Trimmed hedges generally need to have plants closer spaced than hedges for laying. Spacing varies between 200-300mm in the row, with rows 150-400mm apart. Where space or funds are limited, plant in a single row, 200-300mm apart.
Planting can be ‘on the flat’, or with a ditch to one side, or on a bank with or without a ditch. Where there is the space and time available, the creation of a bank and ditch will provide a range of microhabitats, as well as creating an interesting landscape feature. The ditch may be useful for protecting the young plants, or it may invite children to jump and slide and possibly destroy the hedge. Warm, sheltered south facing hedge banks are particularly valuable habitats. Where the water table is high, the creation of a well-drained bank will assist the growth of hedge plants, and the water-filled ditch will be an additional useful habitat, so long as it does not drain and spoil any adjoining wetland.
Ground preparation on fertile soils such as abandoned allotments, parks or gardens involves removing the existing grass sward or other vegetation. This can be done by ploughing, using a rotavator or hand digging, or by spraying a contact or translocated herbicide. Hedging plants, normally transplants 30-45cm high, are then notch planted and well trodden in (Chapter 6 – Trees and woodlands). Planting is best done in November, but can be done any time while the plants are not in leaf, from late October to March.
Establishing a hedge on urban sites with little or no soil, or with limitations of toxicity, pH and other factors is not so easy. Digging a trench and filling it with imported topsoil is a possibility, but may be expensive and not necessarily successful. In poorly drained compacted substrates the planting trench is likely to become waterlogged in winter and dry in summer. On well drained substrates it will support a strong growth of grasses and other herbs which will compete with the hedge plants. On these sites, the growing of a traditional dense stockproof hedge may not be a sensible or achievable aim, whereas an informal hedge of native and introduced species typical of the site or similar sites nearby is more appropriate.
new hedges may be vulnerable to trampling, people taking short cuts, and vandalism. Stock netting or chestnut paling can be used, though this may itself be vandalised or stolen. Protective netting against stock should be at least 1m from the hedge. On larger sites, new hedge plants may need protecting against rabbits, preferably by using rabbit netting. Individual spiral guards can be used, but the aim is normally to prune plants for short, bushy growth, to which a spiral guard cannot be fitted. Various shrub shelters and other products are available, but add considerably to the cost of the hedge. keeping the base of the hedge weed free removes cover for voles, which may otherwise gnaw the bark. This can be done by hand weeding, herbicides or mulching roll. However, mulching roll or mats may themselves provide cover for voles.
Ancient and new planting methods
Hedges in urban areas do not usually need to be stockproof, nor need to follow the specifications of grant-aiding authorities or the traditions of rural hedging. There is room for non-standard techniques of planting and training, as well as choice of species.
A planting technique used by the Romans was to place seeds of suitable species into the fibres of a rope, and then lay the rope along a prepared furrow to form the hedgeline. Similar methods are recorded of twisting straw into loose ropes and setting the seed within it. The likely success is not known, but it could be fun to try where the outcome is not too critical.
Layering is an ancient technique for propagating plants. This involves pegging down a live stem from a plant, which then produces roots and new plants at points along the stem. This technique is sometimes used when restoring an old gappy hedge, to produce new plants to fill the gaps. A similar technique can be used with new plants, by laying them horizontally instead of planting them upright, giving more plants for your money. Hawthorn, blackthorn, holly, crab apple, cherry and rose can be successfully layered. Climbers such as clematis and honeysuckle can be propagated this way to grow through hedges and fences. Tall, leggy plants which may otherwise be rejected are good material for horizontal planting. You may be able to get some publicity out of a horizontal planting project, but make sure you present yourself as someone who knows what they’re doing!
Another old method, made easier by modern machinery, is to transplant mature hedge plants. Hedge moving is now sometimes specified in road widening schemes, as it is possible to dig up mature, trimmed hedges in winter, and transplant them to another location. Many gardeners have successfully moved large garden shrubs, often with little regard to season. Old hedgerows should not be dug up, but any that cannot be saved in situ can at least be transplanted. keep an eye on local development work which may be a source of reject hedge or garden shrubs. Evergreens should be left unpruned, but others can be pruned back at almost any season to lessen transpiration, reduce the bulk for easy moving, and to make them look unattractive to potential thieves. Mature shrubs, securely planted, should be robust enough to survive casual vandalism.
Care of the young hedge
The care is similar to that of young trees, and involves mulching and weeding for the first three or so years. Watering through a drought in the first season after planting may be necessary.
Hawthorn and blackthorn are normally cut back hard to 100mm above the ground immediately after planting in autumn, or if planted in early spring, cut back in the following autumn. This encourages bushy growth. The hedge is then pruned back by a third in late winter for the following 3-4 years. Pruning immediately after planting also has the advantage of making the new plants less visible, and less easy to break or pull out. Where vandal deterrence is important, all the species mentioned above, except holly, can be hard pruned after planting.
An alternative to early pruning is to lay the hedge in the year after planting. The young stem is cut half to three-quarters through at 100mm above ground level, bent over and the twiggy growth is anchored into its neighbour. The shrub regrows from the cut, and from along the bent stem, making a thick, bushy hedge. This has been successfully done with hawthorn, and may work with other species. At worst, if the stem breaks, the plant has merely been pruned.
Hedge laying
A new hedge is normally laid when it has reached the height of about 2.4-3.6m tall. The main stems are selected for pleachers, which will be partially cut and laid. The first group of pleachers are cut and laid to one side, until there is sufficient room to lay a pleacher into the hedge. The cut in the pleacher should be about 30-100mm above ground, and just over three-quarters through so that the stem bends without being forced. The pleacher should lay upwards at an angle of between 25-45 degrees, and angled across the width of the hedge. Prepared stakes of hazel or ash, or commercial softwood stakes, about 1.4-1.8m long, are then knocked in and the pleachers woven between them. Slender binders of hazel, willow, clematis or other available materials are then twisted along the top to hold the pleachers in place. The brushy ends of the laid pleachers are best left uncut, to protect the hedge from being pulled apart by vandals. newly laid hedges also unfortunately make interesting adventure play structures for children to climb and jump on. A few strands of barbed wire should act as a deterrent during the first winter after laying. Remove the following spring.
For further information on hedge laying, including restoring old hedges, see Hedging.
