Hedges

The outer limits of your garden are likely to immutable. They define its boundary, and they constrain the direction, strength, humidity, and temperature of the prevailing winds, and these in turn constrain what you plant in it.

Given that the boundary is the least flexible part of your garden, and that whatever goes within will be dependent on its influence, forming the boundary is the best place to begin your permanent planting.

The selection of species is guided by what will grow well, plus what you want it to do for your garden. If there's a constant drying wind, your hedge must be resistant to desiccation. If your garden is sheltered from light breezes but occasionally thrashed by gales, your hedge must protect your garden during bouts of serious weather. If you want to exclude livestock (or people), your hedge (ideally) should be thorny.

When planting a hedge, bear in mind that it will occupy the ground for many years. If it's to be clipped, this means that good nutrients will be removed, year after year, to the compost heap. Careful preparation is therefore critical. This can be done in advance, so you can put in new plants as soon as possible after they arrive.

When double-digging and incorporating compost, add bone meal (even whole bones) or rock phosphate; add sand if the soil is heavy, and add extra humus if it's already sandy. If the plants you wish to grow have to be kept waiting, either for suitable weather or for preparations to be made, temporarily store them by "heeling in" their roots in a shallow trench, perhaps in the vegetable patch, for a week or two.

Begin small do not be tempted to starting with tall hedging plants. Tall hedging plants may litreally fly away or be knocked over by the first real wind. The smaller and younger your hedging trees arc to begin with (and the slower growing they arc), the stronger the hedge will eventually become. If you need a fast windbreak, erect a screen of mesh or wattle to give temporary shelter to your plot and to protect the developing hedge.

Another way to combine fast shelter and long-term durability is to begin with a mixture of fast-growing and slow-growing species. By the time the fast ones are past their best the slower, surer ones will be large enough to do the job.

A problem that can arise from this latter approach is that the faster-growing elements might shade out or otherwise overpower the slower ones. To avoid this, plant the slow species on the sunward side rather than behind or between the fast ones; to prevent general overwhelming, it is good to create a double hedge, with a row of slow-growers some distance from (and sheltered but ' not shaded by) the row of fast growers.

Aerodynamics and other effects

Some things about windbreaks are obvious—a permeable barrier is less likely to blow down than a solid one, a permeable barrier causes less serious turbulence on the downwind side than a solid one does. But there are less obvious things. You should he aware of them before going all-out for a perfect windbreak.

Hedges may create a significant region of shade and, in high latitudes, this shade can extend a long way during the colder months. This can be when your plants need sunlight the most, so think carefully about planting a high hedge. Remember that a deciduous hedge, although not providing such a dense shelter as an evergreen hedge, can let light through during the winter.

Hedges also rob the soil of nutrients and moisture. Their roots can extend outward farther than twice their height, and this means that a hedge will compete with anything you plant beside it. If you require a sunny, sheltered site for growing things, it can be better to opt for a non-living fence or wall.

To make the best of these limitations, you can run a path or drive along the foot of the hedge. This way, you won't squander good ground by walking on it, and the path can help to restrict root growth on the garden side—this by compacting the soil.

Hedge management

How you choose to manage your hedge depends on the species it contains and on your taste.

Some factors to take into consideration are as follows:

• Wildlife. Don't clip the hedge while birds are nesting, or when winter berries are provide them food.
• Specimen trees. You may wish to leave some individual components untrimmed in order that they grow into mature trees.
• Shape. When trimming, aim to create an A-shaped or even better—if you've space for a broad hedge or are faced with renovating an old, wide overgrown boundary—an M-shaped cross-section. This encourages basal growth; it keeps the hedge thick and prevents it becoming leggy. In addition to providing wind-proof density, the thick base shelters wildlife.

New hedges

Trees and shrubs intended for growing into a hedge have to be trained from the outset.

You should remove the leading shoot of broad-leaved species immediately after planting: you must chop off a tree with a naturally upright growth habit very low down, but you may prime one that won't immediately shoot upward more gently. Conifers retain the leader until they have attained their intended height.

You should prune back side-shoots; this encourages buds near to the main stem(s) to break and produce a dense framework of branches; this will form the heart of the hedge. Such pruning ensures that, later on, the hedge will be less likely to become hollow in the centre. Aim for slow, sound, solid growth, not fast and open growth.

Pruning overgrown hedges

Most hedging trees and shrubs can be cut back hard, though they might take a few years to recover. Conifers (except yew) generally resent this treatment and are best replaced. Tackle an overgrown hedge in winter or early spring, using clearly visible stakes to mark the new profile, and cut off a foot more all round than you eventually want. Making an A-shaped profile helps prevent lower branches from becoming leggy.

Traditional methods

If there's a local tradition of hedging in your region, you can adopt it. Aside from the issue of modem methods tending to impose needless uniformity, local traditions are based on centuries of experience—they're unlikely to let you down. Ask around, search for old pictures, and do anything else you can to discover how hedges in your region were traditionally managed.

Note the use of three terms.

• Laying. This is a way of taking strong young shoots and bending them to give many new steps low down to thicken a mature hedge.
• Coppicing. This is a way of growing several new trunks where only one existed before.
• Pollarding. is a way of turning the upward growth of a tree into breadth, thereby stimulating buds to break and form a close-set row of new uprights.

Also note that bent stems can be anchored to the ground (above picture) or to other stems; this can be facilitated by bending alternate stems in opposite directions.

Laying a hedge

The principle of hedge-laying is simple. Cut a young, upright stem to two-thirds of the way through and bend it over. The skill in this improves with practice.