Everyone should plant a shrub

These humble heroes can form a backdrop for other plants or be a punctuation mark in a garden

I CAN’T THINK OF the word “shrub”, without hearing it said in a warm, brothy, northern accent by John Cushnie, the gardener and broadcaster who was prematurely taken from this world on the last day of last year. Half a dozen years ago, he published an excellent guide, Shrubs for the Garden (Kyle Cathie), now, unfortunately, out of print. He starts the book with: “Shrub is a lovely word, sliding between the teeth with a soft landing to conjure up the image of a sumptuously bushy plant.”

I’ve thoughtfully said “shrub” dozens of times since – even trying it with an Ulster intonation – and it still sounds like a fat dumpling of a word to my ears. But never mind that, Cushnie’s enthusiasm has forever gilded the word for me, and I always pause for a millisecond’s thought before I say it. And as for shrubs themselves, they are the great, under-appreciated heroes of the garden. Poor old shrubs, they have been left out in the cold in the current fashion for naturalistic planting – a style that depends heavily on airy perennials and grasses. Yet a well-shrubbed garden is one that always has a structure. Herbaceous perennials come and go with the seasons, and after a few years disappear altogether or need rejuvenating. But a carefully placed and properly planted shrub will last decades, a constant reassuring presence – like a tree, but without the emotional investment, or the trunk.

A shrub (or a group of them) can be a backdrop for other plants, or it can be a punctuation mark in the garden – something that makes a planting scheme pause or stop. Tall and slender shrubs can be particularly useful in this way. Berberis ‘Helmond Pillar’ is a classic example, with tiny purple leaves and a staunchly upright habit. When fully grown it is about the same size and shape as a person; any straggly bits that spoil the line can be pruned out in winter.

It loses its leaves in autumn, but they turn fire-engine red before dropping. Another exclamation mark of a plant is the evergreen juniper ‘Sky Rocket’, which ascends 3 to 5 metres. And if you don’t mind a spot of work with the shears, then sweet bay (Laurus nobilis) can be pruned into a stately column – and you can use the aromatic leaves in stews. A formal shape such as this can be achieved in box or Thuja also, and can make a strong counterpoint to the feathery profiles of ornamental grasses and lightweight perennials.

I’m fond of shrubs that you can cut right back to nearly ground level in early spring, and which then sprout anew with larger leaves than normal. The smokebush (Cotinus coggygria) is one such species. It has blue-green, oval leaves and a loose framework of stems. It gets its name because of the plume-like inflorescences, which in autumn look like mini clouds of smoke puffing out from the branches. The foliage of the cultivar ‘Grace’ is maroon-coloured, and has brilliant red autumn colour. Purple filbert (Corylus maxima ‘Purpurea’) is another woody plant to which you can give the big chop. It has large, corrugated leaves that look like those of purple beech, only coarser, and several times the size. Stag’s horn sumach (Rhus typhina) and Berberis thunbergii f. atropurpurea also respond to being severely pruned. In most cases, however, if you cut back the stems like this in spring you sacrifice the flowers and fruits, as you remove the buds made the previous year. Drastic pruning always gives a plant a dreadful shock, so do give it a restorative mulch of something nice afterwards – garden compost, or well-rotted manure.

Winter blooming shrubs are great cheerer-uppers in this dark season – a season that has been especially grim this year. In the midst of our snow and ice, the winter jasmine (Jasminum nudiflorum), a spindly wall shrub with lax, dark-green stems, greeted me daily with starry yellow flowers, a trooper of a plant. And near our gate, Viburnum x bodnantense ‘Dawn’ continued to produce its sugary pink, scented flowers, even when the bud clusters were each wearing a crystalline hat of snow. Daphnes are also perfumed: the evergreen D. bholua ‘Jacqueline Postill’ is one of the most fragrant, but it can be knocked by the cold in extreme winters such as this. Its relative, the deciduous ‘Gurkha’, is hardier.

There is something both vulnerable and brave about shrubs that produce their blooms on bare branches. The contrast between the flimsy fabric of flower and the dark, knobbly stems seems poignant. The witch hazels (Hamamelis) embody this perfectly, with their frail slivers of petal – yellow, rust or ruby, depending on the variety – which seem to fall out of their brown suede buds.

The yellow-flowered ‘Pallida’ is the best smelling, while the reddish-toned ‘Diane’, ‘Jelena’ and ‘Ruby Glow’ are almost scentless, but they give welcome warmth to the cold air. Witch hazels grow slowly-slowly and should not be pruned except to remove badly placed stems, or damaged growth. They also dislike being moved, so make sure to put them in the right place when you first plant them: give them a moist, but not water-logged soil, and plenty of room to grow.

The same could (and should) be said of all shrubs: do check out the requirements before you plant one – or, better still, before you buy one. I’ll leave you with the late John Cushnie’s advice, which he sent down the phone from Killyleagh in Co Down, six years ago: “Be adventurous! But check out what the shrub likes. There is no sense in putting it in the wrong conditions – acid-loving into alkaline or vice versa, or something that isn’t hardy into a tough spot 500 foot up a mountain side. And check the height and spread. Give it enough space. When someone plants a big shrub in a corner where it just hasn’t a chance, it’s almost like watching someone smacking a child. Learn what the shrub likes and plant it. Everyone should plant a shrub.”

jpowers@irishtimes.com