Pruning Boxwood
When and how — Buxus sempervirens
Prune your boxwood in May, June and September — the optimal month is usually June.
You're in the pruning season right now — grab the secateurs.
When to prune?
The shrub boxwood is pruned in May, June and September.
Pruning time depends on when the shrub flowers.
The rule of thumb for ornamental shrubs: spring-flowering shrubs (forsythia, lilac, flowering currant) are pruned immediately after flowering, because they set their buds on last year's wood. Summer-flowering shrubs (buddleia, paniculata hydrangea, hardy hibiscus) are pruned in March, because they flower on wood produced this season. Get the timing wrong and you cut off this year's buds. Evergreen shrubs (yew, box) are best pruned around Midsummer (24 June): the first flush of growth is finished and the plant still has time to seal the wounds before winter.
How to prune boxwood
Boxwood tolerates hard pruning and responds well to regular clipping, which is why it's so popular for formal hedging and topiary. The main pruning windows are May to June and September. Avoid pruning earlier in spring when new growth is soft and vulnerable to frost, and don't prune after early autumn, as fresh growth won't harden off before winter. For formal hedges and shaped specimens, clip in late May or early June once the first flush of spring growth has hardened. A second trim in September tidies up summer growth and keeps shapes crisp through winter. Use sharp, clean hand shears or hedge trimmers; blunt blades tear the foliage and leave brown edges. Aim to remove only the season's new growth—typically 5–10 cm—rather than cutting back into old wood unless renovation is needed. If your boxwood has become overgrown or misshapen, it can be cut back hard into older wood in late April or early May. Boxwood regenerates reliably from old stems, but recovery takes a full season or more. Feed well after hard pruning to encourage strong regrowth. For informal, naturalistic plantings where you want a looser shape, light trimming once a year in late spring is sufficient. Remove any dead, damaged, or crossing branches at the same time. Always clear up clippings promptly—fallen leaves and debris trapped inside the canopy encourage fungal problems, particularly box blight. Disinfect tools after pruning, especially if blight is present in your area, to avoid spreading spores between plants.
Common mistakes
✗ Hard-pruning all hydrangeas in early spring
Mophead hydrangea (Hydrangea macrophylla) flowers on old wood — cut it back in March and you get no flowers. Paniculata flowers on new wood and can be cut back hard. Check the species first.
✗ Trimming everything to the same length
Looks 'chopped' and weakens the shrub. Instead, remove one in three of the oldest stems each year right down to the base (renewal pruning). This keeps the shrub vigorous and natural in shape.
✗ Pruning in summer heat
Fresh cuts dry out quickly in full sun and become an entry point for fungal disease. Wait for an overcast day or postpone until autumn.
