Pruning Smooth Hydrangea

Prune smooth hydrangea 'Annabelle' in March, just as the buds begin to swell but before new growth properly starts. This hydrangea flowers on the current season's wood, so spring pruning won't sacrifice blooms—in fact, it encourages stronger stems and larger flower heads. You can prune hard without worry. Use clean, sharp secateurs or loppers. For a tidy, compact shrub, cut all stems back to about 30–50 cm from the ground, just above a pair of healthy buds. This hard pruning produces vigorous new shoots that carry the big white blooms in summer. If you prefer a larger, more informal shape, you can prune more lightly, removing only a third to half of each stem's length, but be aware that lighter pruning often results in more but smaller flowers, and the stems may flop under the weight of the blooms. Always remove any dead, damaged, or crossing branches entirely, cutting back to the base or to a strong outward-facing bud. If your plant has become congested, thin out a few of the oldest stems at ground level to improve air circulation. Some gardeners leave the dried flower heads on over winter for structure and interest, then remove them during the March prune—this is perfectly fine and won't harm the plant. Avoid autumn or winter pruning, as this can expose tender new growth to frost damage.