How to Reduce the Size of a Huge Hydrangea

Hydrangea (Hydrangea spp.) graces gardens in U.S. Department of Agriculture plant hardiness zones 3 through 9. A hydrangea left on its own without pruning can eventually get out of hand, outgrowing its location and its purpose. If you have a big, or even huge, hydrangea, you can prune it to the desired size. Some hydrangeas bloom on old wood -- the previous season's growth -- so prune them right after they bloom.

Hand-held pruners

Lopping shears

Cut dead and old, gnarly branches down to the ground with hand-held pruners. Use lopping shears if the stems are too big or too tough for pruners.

Remove branches that cross or crowd each other. Cut them all the way to the ground. This opens up the bush to light and air, causing the plant to have fuller vegetation from the center, outward. You should be left with, approximately, the healthiest two-thirds of the original plant.

Trim the remaining branches to about half the size you want them to ultimately grow. Cut just above a set of leaves, leaving the stems no shorter than 12 inches. Trim to maintain a round shape.

Hydrangea flowers last so long that you can't really wait until they're finished in fall to prune them; you'll cut off the following year's buds, destroying their show. Enjoy the blooms for a few weeks, and then prune.

To minimize the loss of bloom, remove one-third of the plant each year. After the third year's cutting, you'll have a smaller, fuller and more vigorous shrub. If the bush is woody and leggy, as oakleaf hydrangea (Hydrangea quercifolia, USDA zones 6 through 8) often is, use this approach.

Panicle hydrangea (Hydrangea paniculata, USDA zones 3 through 8) blooms on new wood, so prune it in late winter or early spring.

As a precaution against spreading plant pathogens, disinfect pruning blades with rubbing alcohol before and after each pruning job.