Jolly green giants: How to pick enviable evergreens

Some say every garden needs an evergreen. But which one to choose – the prettiest or the hardiest? Anna guides you through the picking process.

"All gardens must contain 10 per cent of evergreens," I read this week. The piece was written by a garden designer, wonderfully sure that his edicts had been handed down by Moses himself. Any edict has me reaching for my anarchist T-shirt, but in this particular one, there was an element of truth. My objection would centre on the actual percentage.

In gardens there's no such thing as a universal solution. In towns, for instance, you might use more evergreen plants, to ameliorate the overwhelming presence of bricks, Tarmac and mortar. But there again, if the garden was very small, you'd be careful of putting anything in it that would loom disproportionately out of its space. A hedge of Leyland cypress can become a prison rather than a pleasure.

Much depends on how you define evergreen. If, as a new gardener, you read the decree above, you'd probably think first of trees. Then shrubs. And you'd be right, because in terms of scale, no garden can do without those comfortable large pieces of furniture. Holly is out of fashion. Too slow. Too unfriendly with its angled prickles. But it remains my favourite evergreen tree, because of the amazing, light-reflecting gloss of its leaves.

And it's a British native, which in the xenophobic mindset that seems to prevail among environmentalists just now, puts you on the side of the angels. And makes up for the fact that you are still buying bottled water. You'd get the same plus points if you went for box or yew, both of them native evergreens. But box is still plagued by blight, and clipped box (so vogueish, so instantly structural) seems more prone to attack than unclipped. Yew, although usually confined within the straitjacket of a hedge, makes a magnificent piece of evergreen topiary, especially if you use Taxus baccata 'Fastigiata', the upright-growing form discovered on a hillside in County Fermanagh more than 200 years ago. When we came here, we planted six of them, zig-zagging through the flower garden. That was only six years ago and already, at 7ft, they are as tall as I want them to be.

As a precaution, two summers ago, we tied them round with fishing line. It's invisible, but stops the side branches splaying out under the weight of snow. I wasn't planning anything complicated, just simple evergreen pillars rising between the more evanescent displays of tulips, columbines, thalictrum and iris. This summer, we topped off the yews and it had an extraordinary effect. Suddenly they were finished pieces of sculpture. In winter, they pull the eye where it needs to be, above the rotting mounds of herbaceous plants (the big arums are at their squelchiest worst).

Winter, of course, is the season when evergreen plants really earn their keep – even spotty laurel (Aucuba japonica), the stalwart of Victorian shrubberies. I couldn't ever be passionate about spotty laurel. It's not the kind of thing you swoop on in the garden centre saying "I've always wanted one of these". Poor aucuba. There is nothing more dreary than being described as useful. Its tragedy, of course, is that we take it too much for granted. It never looks as though it is going to keel over from ill-health. It withstands frost, tempest and drought. It puts up with less-than-brilliant growing conditions. It does not mind shade. The thing is a paragon, but still we do not love it.

But the bulk of it in winter, when so many things have shrivelled back to skeletons, is comforting. The colour, bright green-flecked and streaked with gold, is warm in fog and frost. It is generally as wide as it is high, and will shield you permanently from views you would rather not see. It rarely gets above 3m (10ft). The branches are lax and arch outwards when they get heavy with leaves.

It needs no regular pruning. Because it has such large leaves, it is better left unclipped. If you want to reduce its size, work on a branch at a time, tracing back the piece you want to get rid of to its junction with another branch and making the cut there.

Cutting back some of the growth on a regular basis stimulates a supply of fresh growth and this will have bigger and shinier leaves than those on old branches. April is the best time to do this, but aucuba is a forgiving plant and will excuse some snipping at any time of the year. Nesting birds love its dark, dry undergrowth. They must like the red berries, too, as there are few left on bushes round us.

Smaller and neater is the shrub osmanthus, either in its plain, dark evergreen form, or the showier Osmanthus heterophyllus 'Variegatus'. I like its leaf, dark, evergreen, jagged, rather like a holly leaf, but not as prickly and, in the variegated form, edged in an absent-minded way with cream. It grows well in a pot and will fill a corner boldly, giving bulk to more frippery displays of winter pansies. It doesn't seem to mind shade, and grows slowly to make a rounded bush, as wide as it is high. The variegated one is more compact than other forms, but shyer to flower. It doesn't need regular pruning, but if it began to look lopsided then I would snip at it in April.

Wandering round our place, I'd say that the best things in the garden at the moment are the columnar yews, along with big mounds of rosemary, myrtle and shrubby spurges, such as Euphorbia stygiana and E. x pasteurii. Snowdrops have been flowering since Christmas. So have primroses. The hellebores are in bud. But, in this dreary month, the evergreens are what catch the eye. Foliage is more important than flowers. Oh Lord! I think I might have caught edict-fever too.