How to prune clethra barbinervis

Late winter to early spring before new growth emerges. Remove dead and crossing stems back to a healthy outward-facing bud or branch junction. Lightly thin up to one-quarter of the oldest stems at the base to open the canopy; avoid cutting back hard into old wood.

Annually. Clethra barbinervis (Japanese clethra) benefits from annual pruning to maintain shape and encourage the fragrant late-summer flower spikes. Remove dead, crossing, or weak stems and lightly thin crowded growth. Avoid heavy cutting as flowers develop on current-season wood — hard pruning delays blooms and removes the attractive exfoliating bark display.

Remove dead and crossing stems back to a healthy outward-facing bud or branch junction. Lightly thin up to one-quarter of the oldest stems at the base to open the canopy; avoid cutting back hard into old wood.