Seasonal greens

In deep winter, green in all its forms is a potent symbol of life, a reminder that the rest of the garden isn't dead but merely resting, writes FIONNUALA FALLON

A short time ago I was given the opportunity to visit Castletown Cox, a private garden in Co Kilkenny whose graceful bone structure of paths, steps, statuary, fountains, lawns and sculptural hedges had been laid bare by winter, and yet which was still as lovely as any garden I've seen at the height of summer.

Its singular beauty was the result of a skilful, restrained design that makes masterful use of all sorts of evergreens; tightly shaven boxwood parterres, velvety lawns, serried lines of mop-headed holm oaks, clipped bays, and sheared yew hedges cut with such geometrical precision (the gardeners use a laser level) that they appear almost to have been built rather than grown.

I loved every bit of this garden, not only for its restrained elegance but also for the opportunity it gave me to appreciate the colour green in all its complementary shades, from the black-green of coniferous yew to the khaki shades of evergreen oak.

Green, as any armchair psychiatrist will tell you, is a soothing, restful colour, symbolic of health, youth and fertility, and associated with resurrection and regeneration. In the summer garden, it's the all-important foil for other brighter colours, the glue that binds a flower border together. In deep winter, it's a potent symbol of life, a reminder that the rest of the garden - its deciduous and herbaceous plants - isn't dead but merely resting.

Some of my favourite evergreen plants are those that can be pruned, primped and shaped into tightly knit hedges and sculptural shapes; boxwood, holly, yew, holm oak, bay and Portuguese laurel come top of this particular list. Grown as hedges, these can give shelter, screen eyesores, frame a view or subdivide a space. Boxwood in particular is a supremely adaptable plant, suitable for even the smallest garden, its dense growth habit easily lending itself to topiary balls, spirals, cones, cubes, obelisks and even more fanciful shapes.

Its only downfall is its vulnerability to box blight, a defoliating disease caused by two fungi (Cylindrocladium buxicola and Volutella buxi), to which the most compact form, Buxus 'Suffruticosa', is particularly susceptible.

While I've seen gardeners control this disease with powerful chemicals, I've also seen its spread effectively prevented by good gardening practice.

This means giving plants a free-drained soil enriched with organic matter, top-dressing with manure in spring and liquid feeding every two to three weeks during the growing season with a seaweed-based fertiliser to boost plant health and disease resistance.

Pruning should be carried out in dry weather and in late spring/summer after any risk of frost has passed. Treating the shears with an antibacterial spray and collecting all the clippings also helps to prevent the spread of the disease.

Yew (Taxus baccata) is boxwood's larger, more imposing cousin, a coniferous plant that also tolerates sharp pruning with equanimity and can be used to create a range of shapes and forms. Just like box, this plant hates poorly drained soil and does best when given a fertile, free-draining site enriched with manure. In wet gardens, I've seen it successfully grown when planted into a deep trench lined with coarse stone and infilled with manure and topsoil. But don't waste your money on larger, more expensive specimens - younger plants will establish far more quickly.

The evergreen lollipop tree beloved of smart town gardens is the culinary bay laurel (Laurus nobilis) and a native of warmer Mediterranean climates - a fact brought home to Irish gardeners over the cold winters of 2009 and 2010 when the plant's aromatic foliage was badly scorched by icy winds and freezing temperatures, or (worse still) it simply died. Container-grown specimens often suffer from a combination of being underfed, under- or over-watered, poorly pruned and pot-bound.

To keep them in good shape, re-pot every second year in spring using a soil-based compost enriched with slow-release fertiliser. Liquid feed regularly during the growing season with a seaweed-based fertiliser and trim to shape in summer. On really cold winter nights (below -5C), give it protection.

Prunus lusitanica, the evergreen Portuguese laurel, is not dissimilar to the bay laurel in appearance and growth habit, but is far hardier. It too looks wonderful used as a stand-alone topiary specimen (for example, the dome-shaped "umbrellas" in Powerscourt Gardens in Co Wicklow) or as a tall, glossy hedge. By comparison, the foliage of the holm oak (Quercus ilex) is a duller, muddier green, yet this is still a versatile, useful evergreen.

Finally, there is that stalwart of the winter garden, which is holly (Ilex sp) in all its various plain-leafed and variegated incarnations.

Holly is slow-growing, hardy and long-lived, and its leaves are a symbol of good will, peace, health and happiness. Little wonder, then, that it's also our favourite Christmas decoration.