Pruning Bougainvillea
When and how — Bougainvillea glabra
Prune your bougainvillea in March and August — the optimal month is usually August.
The next pruning window is August.
When to prune?
The climber bougainvillea is pruned in March and August.
Climber pruning is about structure and keeping space against the support.
Pruning climbers does two things: keeps the plant on its support and lets light and air through. Timing depends heavily on species, and flowering season points the way. Spring-flowering clematis (Group 1, e.g. Clematis montana) is pruned immediately after flowering in May or June; summer-flowering clematis (Group 3, e.g. Clematis viticella) is cut back hard to 30 cm in March. Climbing roses are thinned in February, keeping the horizontally-trained main stems and shortening side-shoots to two or three buds. Wisteria needs two prunings a year (July and winter) — without them it simply won't flower.
How to prune bougainvillea
Bougainvillea flowers on new growth, so pruning encourages a flush of colourful bracts. Prune twice a year: lightly in March before new growth begins, and again in August after the main summer flowering flush. In March, cut back the previous year's growth by about one-third to one-half, reducing long, leggy shoots to a pair of healthy buds. This stimulates branching and keeps the plant compact and bushy. Remove any dead, damaged, or frost-touched stems entirely, cutting back to healthy wood. Use clean, sharp secateurs or loppers; bougainvillea stems can be thorny, so wear sturdy gloves. The August prune is lighter: trim back spent flowering shoots by 10–15 cm to tidy the plant and encourage a late flush of colour into autumn. Don't prune too hard at this time, as you want the plant to harden off before winter. Throughout the growing season, tip-prune wayward shoots to maintain shape and direct growth where you want it. Bougainvillea can become unruly quickly, so little-and-often trimming is more effective than one drastic cut. If your bougainvillea has become very overgrown or woody, you can renovate it in March by cutting back hard—even to within 30–50 cm of the base. It will usually reshoot vigorously from old wood, though flowering may be delayed that year. Always prune just above a node or bud to encourage clean regrowth and avoid leaving stubs that may die back.
Common mistakes
✗ Skipping the July prune on wisteria
Wisteria flowers freely only if you cut the long whippy shoots back to 5–6 buds from the main framework in July. Skip it and you get plenty of leaf and almost no bloom.
✗ Pruning all clematis the same way
Clematis are divided into Group 1, 2 or 3 — each pruned differently. Group 1 not at all (flowers on old wood), Group 2 lightly in February, Group 3 hard in March. Always check the group before you reach for the secateurs.
✗ Letting climbing roses grow vertically
A climbing rose trained horizontally flowers along its entire length. Trained vertically it only flowers at the top. Plan this from planting time with your support.
Hold off on pruning
Better to wait than prune at the wrong moment. The next optimal window is August. Until then: leave the plant alone — only remove dead or diseased wood (which you can do year-round).
