Can buddleja be pruned back hard?
Paul Leigh, by email
Stefan says: I assume you’re asking about the butterfly bush Buddleja davidii and not the June-flowering Buddleja alternifolia or any other species. You have more or less the right idea in that it does require hard pruning but ‘back to the ground’ is a bit extreme. The time to do it is in mid-March.
I cut mine back to between 30cm (1ft) and 1m (1⅓ft) above ground level, depending on the plant’s size. Where possible, prune just above a bud or growing shoot. Remove any dead stubs and branches using a pruning saw or loppers. Cut these back flush with the main trunk. Also thin out any crossing branches to prevent rubbing, and remove spindly growth coming from the base. Once finished, place a thin layer of mulch around the bush to suppress weeds and help the soil retain moisture.