Pruning Vs. Deadheading for Hydrangeas

Pruning

• While some hydrangeas don't need pruning to grow vigorously, this type of care can help other varieties. No matter which type of hydrangea you have, a few circumstances require pruning. Always cut away dead, damaged or diseased branches of the hydrangea, as with all shrubs. These branches force the shrub to expend energy that would be better spent on new or stronger growth. In general, hydrangeas have a naturally appealing shape and don't require shaping.

Deadheading

• Deadheading is the act of cutting away spent blooms to give your hydrangea shrub a cleaner, tidier appearance. While some people enjoy the dried, brown flower heads hydrangeas produce, others don't. It's a matter of personal taste. When deadheading, cut the spent flower heads off by placing your pruning shears in the crotch of the leaves or buds on the same stem and just below the flower head. Deadheading can improve the chances for additional blooms.

Old Wood Bloomers

• Pruning times for hydrangeas depend on when they set their buds; like all flowering shrubs, hydrangeas bloom on either old or new wood. Most garden-variety hydrangeas bloom on old wood. Bigleaf hydrangeas (Hydrangea macrophylla) and mountain hydrangeas (Hydrangea serrata), both of which grow in U.S. Department of Agriculture plant hardiness zones 6 through 9, as well as oakleaf hydrangeas (Hydrangea quercifolia), which grow in USDA zones 5 through 9, are all examples of old-wood bloomers. Pruning these types is rarely necessary, but if you feel the need to prune these specimens, prune them just as the flowers begin to fade to reduce the risk of cutting away new, developing buds.

New Wood Bloomers

• On the other side of the pruning spectrum are the hydrangeas that bloom on new wood. These varieties include panicle hydrangeas (Hydrangea paniculata), which grow in USDA zones 3 through 8, and smooth hydrangeas (Hydrangea aborescens), which grow in USDA zones 4 through 9. Pruning actually helps these varieties and is best done in late winter or early spring before they begin to leaf out. For bigger blooms on these varieties, cut them back to approximately 18 to 24 inches above the ground. Another option is removing the oldest canes of the shrub to improve growth.