Country & Garden: Great barrier grief

From almost the earliest days of human settlement, a hedge has been a potent symbol of protection and shelter. It is also a powerful symbol of restraint, boldly marking the limit of our territory and, therefore, ambition. When used to make a maze, the hedge becomes an allegory of our earthly journey, with a central desirable goal from which we are too often distracted or misled. A hedge carries a lot of cultural baggage with it.

A clipped, non-flowering hedge connects and softens the transition between house and garden. Without the internal hedges (yew and hornbeam) which I have planted, my garden would lack shape and mystery, and I love these hedges as much for their looks as their utility.

Not so the inherited Leyland cypress hedge which defines one of the garden's boundaries. Twice a year, with teeth clenched, I trim this hedge to keep it in check. I have not yet had the nerve to grub it up and start again with something better. For years, we gardeners were assured by experts and nurserymen that the Leyland cypress, X Cupressocyparis leylandii, was the solution to the widespread need to provide a quick-growing screen or hedge; its capacity to grow 10 feet in five years seemed ideal for our impatient times.

We then discovered by bitter experience that unless frequently and ruthlessly controlled with saw and trimmer, this plant had the capacity both to condemn neighbours to a mole-like existence, in houses and gardens untouched by sunlight, and to provoke border disputes of almost Balkan intensity. The problem is that the Leyland cypress, like an over-excited child, does not know when to stop or even markedly slow down.

Now that its reputation has taken such a deserved nosedive, gardeners must cast around for decent evergreen alternatives.

There are several: western red cedar, Lawson cypress, laurel, privet, holly, Cotoneaster lacteus. But for me, the finest evergreen hedge by far is the English yew. Taxus baccata is a noble tree, whose wood was used to make the longbows at Crecy and which, if left to itself, will live for a millennium. It has more than its share of cultural baggage. But its looks and amenability are what matter. The close-knit nature of the young shoots, from which arise on each side two tiers of flat, dark green leaves, ensures an excellent finish on cutting.

The yew provides the darkest - and therefore best - background to colourful flower borders. Being native, it is absolutely at home in our climate, in sun or shade and in all soils, provided that they are not prone to waterlogging. Like almost all native trees, the yew will stand being cut very hard, indeed right into old "wood", which means that neglected hedges can be renovated easily, and it can be used for any topiary frivolity that the human mind can devise.

There are two reasons why there are not yew hedges in every garden. The first is that every part of yew (except the red "aril" round the seeds) is poisonous to livestock, even when dead, which means that it must never be planted as a boundary hedge adjoining pasture or paddock. The other drawback is that it is perceived as being slow-growing. In relation to the Leyland cypress this is true. Yet if care is taken to plant the hedge in well-worked soil, enriched with organic matter, to which each April is added a handful of dried blood fertiliser per plant, you will be agreeably surprised. In six years you will have a hedge six feet high, and knitting together nicely, thank you. I should certainly like a pound for each time someone has confided in me their regret at not planting a yew hedge when they first came to a garden.

Mid-September, when the soil is damp from the first autumn rains, is pretty well ideal to plant yew hedging if your soil is light. April is a better time in clay gardens.

When buying hedging, take a good look at the plants available in the garden centre and check that they are more or less identical to each other. There are lots of different strains of English yew about, and if you get a mixture your hedge will always lack uniformity.

Yew needs to be planted more shallowly than shrubs - in fact the topmost roots should lie only just below soil level. This is to help prevent the roots from dying if the soil should become temporarily waterlogged. Plant them 45-60cm apart in a single line (or curve), and mulch well. In exposed gardens for the first two winters, erect a barrier of windbreak material on the windward side. For the first three years, trim the hedge lightly every six weeks or so in summer to help thicken it up, but leave the leading shoot alone until it reaches the required ultimate height. After that, a single clip every August or September will suffice, although an additional trim in June will make for the perfect hedge.