How to prune grefsheim spirea

Immediately after flowering, typically April–May. After blooms drop, cut one-third of the oldest stems to ground level to stimulate vigorous new arching shoots from the base. Lightly trim the remaining stems to shape. Avoid autumn or dormant-season pruning, which removes next season's flower buds carried on that year's growth.

Annually after flowering. Grefsheim Spirea (Spiraea cinerea 'Grefsheim') is a white-flowering early-spring bloomer that flowers on old wood. Prune immediately after the flowers fade — not in spring or autumn — to avoid cutting off next year's buds. Thin out one-third of the oldest stems at the base each year to encourage vigorous new arching growth.

After blooms drop, cut one-third of the oldest stems to ground level to stimulate vigorous new arching shoots from the base. Lightly trim the remaining stems to shape. Avoid autumn or dormant-season pruning, which removes next season's flower buds carried on that year's growth.