Garden: A budding time for optimists

AT FIRST sight, mid-April may not seem a good moment for flowering shrubs, in gardens on alkaline soils, at least. Most seem thoroughly eclipsed by the floraison of hardy bulbs and ornamental fruit trees. By this time the forsythias have lost their power to startle, and have settled down to another 11 months of self-effacing dullness, while the white flowers of evergreen osmanthus, gloriously scented and profuse as they are, are already past their best. The flowering currants (Ribes) are on their way out as well, although I wish I could say the same of the long-lasting Berberis darwinii, whose small bell flowers are a frankly rather unappealing orange.

There is a small group of related shrubs, however, whose flowering in mid-spring plugs a gap before the lilacs hit their stride, and whose charm fills me with a wild optimism, a belief that if spring can go so well, perhaps all will be well in summer too. This is irrational, of course, and is usually soon dissipated, but the dependability of the deciduous viburnums is certainly highly reassuring, even if the exact timing of their flowering depends on climatic conditions, and occasionally a late frost will brown the flowers.

Perhaps, some time in the last few weeks, you have noticed one of these shrubs masking a public lavatory or car park, and wondered what those brave, distinctive, rounded heads of pink-budded, white, tubular flowers, among emerging silver-backed, gleamingly fresh green leaves, could be? Perhaps, if you were close enough, you caught a sweet scent, a fresh, summery fragrance, like that of a species rose, and maybe thought that life was good? More than likely what you saw was Viburnum carlesii or one of its hybrids, V x juddii or V x carlcephalum.

V carlesii is a Korean shrub, introduced to this country, via Japan, in 1902. It makes a rounded shrub about two metres across, with toothed, ovate leaves up to 10cm long which turn an attractive red in autumn before they fall.

The clusters of flowers, pink in bud and white when mature, are often followed by red berries in late summer. There are two really good forms of it in commerce, `Aurora' and `Diana', whose flowers are deep pink in bud and pale pink in flower. Viburnum carlesii is considered by some to have the best scent of any viburnum, and that is saying a great deal. It has also turned out to be the parent of some excellent hybrids.

V x juddii, for example, is an offspring of V carlesii and a closely related species called V bitchiuense. I grow two of these, one each side at the top of some steps in the garden, in front of a yew hedge which acts as an effective backcloth.

In early April (in a forward year such as this) the tight, bright-pink, pincushion buds open to reveal fragrant, tubular white flowers; they don't differ a lot from those of V carlesii, except in being held in more loose, open, slightly larger heads. The deeply veined, oval leaves, about 6cm long, begin to unfurl at the same time, so that the shrub gradually acquires density and presence.

This shrub grows only to about 1.5 metres tall and 1.2 metres across, which makes it ideal for a modern garden.

The other deciduous and closely related viburnum is V x carlcephalum, whose parents are V macrocephalum, otherwise known as the "snowball bush", and V carlesii. It makes a much larger, more vigorous and upright shrub than V juddii, and has longer leaves and bigger heads of flowers (as much as 15cm across). It also blooms a week or two later.

Which you choose depends on the space you have, for it is impossible to say which is best.

The deciduous viburnums are as hardy as eskimos, as tolerant of soil conditions as you could wish (though they will do best in a fertile, moist but well-drained soil) and will grow in partial shade, though they flower most profusely in full sun. They will take hard pruning, which means that, if you cut them to shape in late spring or early summer, you can make a flowering hedge or even twiggy topiary shapes out of them.

Moreover, because they lose their leaves in autumn, they make suitable thin shelter for spring bulbs. To coincide with the shrubs flowering, plant small, late narcissi, such as `Thalia', grape hyacinths, like Muscari armeniacum, and, in the wilder parts of the garden, bluebells beneath them.