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Why a timber pergola is the perfect host

A timber pergola does two jobs at once. It gives you shade, structure and a sense of enclosure, and it provides the sturdy, warm-toned framework that climbing plants love to scramble over. Timber is kinder to stems than metal, particularly in hot sun, and it holds far better than a painted wall for self-clinging types as well as twiners. The trick is choosing climbers that suit the aspect you have, rather than the aspect you wish you had, and then training them patiently from the first year.

Get that pairing right and a pergola becomes the best-looking part of the garden within three or four seasons. Get it wrong and you will spend your summers fighting a plant that sulks in the shade or frazzles in full sun.

Match your climber to the aspect

Before you buy anything, spend a day watching the pergola. Note where the sun lands at midday and how long each post and beam stays in light. Most climbing plants fail not because of cold, but because of the wrong light levels and dry, baked roots.

• South or west facing: the hottest spot. Choose sun-lovers such as jasmine, wisteria, passionflower or a climbing rose. Watering becomes the main task because timber posts and raised beds dry out fast.
• East facing: morning sun, softer afternoons. Clematis and honeysuckle are happiest here, and the flowers last longer without fierce midday heat.
• North facing or dappled shade: limited but workable. Look at Clematis alpina, Clematis montana or a shade-tolerant honeysuckle. Avoid sun-worshippers entirely; they will simply refuse to flower.

Wind matters too. A pergola at the corner of an exposed plot funnels air, so tender evergreens need a sheltered position or a temporary fleece screen in winter.

Clematis: the workhorse of any pergola

No other genus offers such variety, and none rewards a pergola quite so well. The key is knowing which pruning group you have bought, because that determines when you cut and therefore when you get flowers.

• Group 1 (such as Clematis montana and C. alpina) flower in spring on the previous year's growth. Prune lightly straight after flowering, never in winter.
• Group 2 (large-flowered doubles and early singles) flower in late spring and again in late summer. Trim lightly in late winter, cutting back to a strong pair of buds.
• Group 3 (including the viticella types) flower from midsummer onwards on new growth. Cut the whole plant back hard to about 30cm in late winter for a fresh, floriferous season.

Whatever the group, clematis insists on cool, shaded roots and a warm head. Plant it roughly 30cm away from the post, angled towards it, and shade the base with a low-growing shrub or a flat stone. That single habit prevents the wilt that so often takes young plants.

Honeysuckle, jasmine and fragrant companions

For evening scent drifting over a seating area, nothing beats honeysuckle. Our native Lonicera periclymenum and its cultivars are reliable, wildlife-friendly and happy in most soils, flowering best with roots in shade and growth in sun. Twist the stems gently round the posts rather than forcing them; they spiral naturally.

Summer jasmine (Jasminum officinale) needs a warm, sunny wall or post and a sheltered spot to perform. In colder gardens, star jasmine (Trachelospermum jasminoides) is the better bet, though it too appreciates protection from hard frost. Both respond well to a light trim after flowering to keep them from tangling into the beams.

If you want flowers and scent in one, consider a climbing rose trained along a beam, with a clematis threaded through it for late-season colour. The two share the same framework happily, provided you leave room for air to move between them.

Planting and training a young climber

Autumn and early spring are the best planting windows, while the soil is workable and the plant is dormant. Dig a hole at least twice the width of the rootball, fork in plenty of well-rotted compost, and set the plant so the crown sits at the same level it did in the pot. Water thoroughly, then mulch with bark or compost, keeping the mulch clear of the stems.

Training starts on day one. Fix horizontal galvanised wires or screw-in vine eyes to the posts and beams at 30–40cm intervals, then tie stems in with soft twine or rubber ties in a loose figure-of-eight. Never bind a stem tightly against timber: it will rub, girdle and weaken as it thickens.

Encourage a framework by training the main leader horizontally along the lowest wire. This breaks apical dominance and pushes side shoots upward, which is what fills a pergola evenly rather than leaving a bare, top-heavy clump.

Keeping the partnership healthy

For the first two summers, water deeply once a week in dry spells rather than little and often, and feed with a balanced liquid fertiliser monthly until midsummer. After that, an annual mulch and a spring feed are usually enough.

Check ties each spring. Loosen or replace any that have become tight, and re-route stems that have grown into the joints of the timber. A congested climber traps damp against the wood, which shortens the life of the structure, so thin out overcrowded growth in late winter. If you treat the timber, use a preservative that is safe for plants and brush it on carefully, avoiding stems and foliage.

Do this and your pergola will age gracefully, with the wood silvering under a canopy of flowers that returns bigger and better every year.