Short answer
Formal box hedges are trimmed 2-3 times in the growing season (RHS). A common pattern is late spring, mid-summer and, if needed, late summer. Avoid cutting so late that soft new growth is caught by frost.
Box (Buxus) gives crisp, low formal edging, which means frequent light trimming rather than one heavy cut. Precision matters, so a small, light trimmer or hand shears often suits it.
How to time each trim
- First trim: late spring, once the first flush of growth has begun to harden.
- Second trim: mid-summer to keep lines crisp.
- Final trim: late summer at the latest, so new shoots toughen before cold weather.
Tool tips for crisp box
- Use sharp blades or shears for a clean cut; ragged cuts can brown at the tips.
- Clean and disinfect blades between hedges or plants, as box blight and other diseases can spread on tools. Check current RHS advice for box blight and box tree moth.
- Use a string line for edging and low borders.
- A lightweight trimmer is easier to control for detail work; see lightweight hedge trimmers.
Whatever the species, check the hedge for active nests before you start. It is an offence to intentionally damage or destroy a wild bird’s nest that is in use or being built; see our nesting season guide.