Urban gardener, Cleve West: Mellow yellow

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The reputation of shrubs has, let's face it, taken a bit of a pasting over the years. The froth, pizzazz and prettiness of perennials have wooed many people and made us oblivious to anything the shrub has to say except in winter, when good stem colour (cornus, salix, rubus) or welcome flowers (exochorda, lonicera, chimonanthus) can help to keep our spirits up.

One shrub to gladden the heart in winter and still make itself useful in an urban context throughout the year is mahonia. Slow to acquire a taste for them, my acquaintance began with a somewhat tatty-looking 'Oregon Grape', Mahonia aquifolium, its glossy, holly-like green leaves often warming to red come winter, with soft, lemon flowers. Books will tell you that it grows to a height of 1m and is therefore useful as game-cover. Ours, obviously bewildered and a touch sniffy at the lack of grouse in Teddington, used our ranch-style fencing to lever its way up to 2m as cover for blackbirds, robins and blue tits.

The purple-black berries are edible. I don't know anyone who can vouch for them, but apparently they're tart and, with a disproportionately large stone to small amount of pulp, they're unlikely to affect the sales of blueberries and other fruits of the forest. Because of its role as an understorey plant, Oregon Grape is rarely used in an urban space, but it's often seen on loveless roundabouts or in municipal planting schemes where it will abide neglect without taking it personally. Grubbing one out to make way for a terrace, I recall being astonished by the yellow inner fibre of its branches, which Native Americans used as pigment to dye basketry and quills. Its probing roots are also yellow, fleshy and well-anchored - an indication of their tolerance to drought.

Mahonia japonica, however, is a different story. Common it may be, but quite hardy and a good stand-by for the shadier urban garden. Its ability to stand up for itself while retaining an air of elegance is matched by its beautiful racemes of fragrant yellow flowers that bloom throughout winter - well beyond the call of duty. It is also a fantastic food source for bees who might take advantage of a warm spell and venture out to boost their reserves of nectar. Dark green, pinnate leaves and strong stems impart an obvious architectural note and can quite easily carry the scene as star performer in a small courtyard. Thorny leaves make people wary of this shrub but, with less leaf litter, it's actually easier to maintain than holly and unlike its relative, berberis, the stems are spineless.

For the connoisseur, Mahonia lomariifolia is probably the most striking. It's slightly less hardy, but can generally cope with the shelter of an urban space with mature specimens standing an elegant 3m tall with upright racemes of scented flowers. For anyone with the space, the vision and a little patience, a grove, under-planted with low grasses and bulbs, would be a magical experience. Planted against a wall or a screen, the stiff, fissured stems might make a dramatic focal point, although care should be taken to give the plant room to receive water and nourishment to grow to its best ability.

Occasionally you will see these shrubs looking sad in dry, impoverished, forgotten corners of light-starved courtyards. Some gentle cultivation, a good soak and a mulch of organic compost is not too much to ask for this otherwise undemanding plant. Crossing M. japonica and M. lomariifolia we get M. x media, the best known cultivars being 'Buckland' and 'Charity'. Both bear the striking attributes of their parentage, but the flowers are slightly less fragrant.

As mahonias resent disturbance, the best shrubs are those that have been re-potted each year rather than having been lifted from the ground. Larger plants are occasionally available but usually at the expense of quality. Apart from a preference for acid or neutral soil, most are unfussy about their location, but the taller varieties are happier where soil doesn't dry out too quickly. Cold, drying winds can also be a problem and tender, young growth in spring can be scorched by a late frost. Other than that they are generally trouble-free (even resistant to honey fungus) and can be pruned hard if they get beyond their station.