If there is one thing about hydrangeas that scares people, it's when and how to prune them. They fear that a wrong move can ruin these classic cottage-garden shrubs forever (don't worry, that's not really true—eventually your shrub will set new buds for the next season's growth). So fear not, because we're here with easy guidelines for pruning hydrangeas that will result in beautiful blooms every year in your summer garden.
There are several species of hydrangea , and each blooms a little differently. When to prune hydrangeas basically depends on whether your variety blooms on growth made last year—otherwise referred to as old wood—or on new growth that sprouted during the current year. Let's run down some of the most popular hydrangeas and what to do.
Pruning Smooth Hydrangeas
'Annabelle' hydrangea is the showiest and most popular selection of the native smooth hydrangea ( Hydrangea arborescens ). It produces immense clusters (up to a foot across) of pure white flowers in summer on a shrub that grows about 4 feet tall and wide. It blooms on the current season's growth, so prune it in late winter. Cutting it back to a foot tall each winter produces fewer flower clusters, but they're huge (a trick I learned from Margaret Mosely in Decatur, Georgia). Cutting it back more modestly produces many more, but smaller clusters.
Pruning Panicle Hydrangeas
Panicle hydrangeas ( Hydrangea paniculata ) have more elongated, cone or pyramid-shaped clusters of flowers. This summer-flowering species likes the sun and is often trained into a tree 15 to 25 feet high. The most widely planted selection, 'Grandiflora' (often called "peegee"), bears large, rounded clusters of white blooms that age to rose. Other worthy selections include 'Limelight' (lime green flowers that age to pink), 'Pink Diamond' (creamy flowers that age to rosy-red), and 'Tardiva' (late-opening, arrow-shaped clusters of white flowers that age to rose). Panicle hydrangea blooms on new growth, so prune it in late winter.
Pruning Oakleaf Hydrangea
Oakleaf hydrangea ( Hydrangea quercifolia ) is an outstanding native that grows 6 to 8 feet tall and wide and has highly lobed leaves like an oak tree. The leaves turn a striking burgundy red in fall. Among our favorite selections are 'Snowflake' (the inner florets stay white, outer florets turn rose in summer), 'Harmony' (huge clusters of double white flowers), and 'Pee Wee' (a dwarf plant to 3 feet tall that blooms at a young age). Oakleaf hydrangea blooms on old wood, so prune it back (although it rarely needs it) in summer just after it blossoms to avoid cutting off next year's flowers.
Pruning French or Bigleaf Hydrangeas
French or bigleaf hydrangeas ( Hydrangea macrophylla ) are by far the most popular of all hydrangeas for their showy, blue or pink, snowball-shaped blooms. A few popular varieties are lacecaps, meaning they have a cluster of tiny flowers surrounded by sterile, fluttery flower petals. Most selections, such as the standard blue, 'Nikko Blue,' bloom on last year's growth. Before pruning, wait until they start leafing out in spring. You'll probably notice some stems are light brown with no signs of life. Prune them back to just above where you see fat, green buds starting to open. Most of these buds should produce flowers. Immediately after the flowers fade in summer, cut these stems back if you wish.
There are exceptions to these guidelines, however. Newer, repeat-blooming selections of French hydrangea, such 'Endless Summer,' 'Pennymac,' 'Mini Penny,' and 'Forever and Ever,' bloom on both last season's growth and the current season's growth. You can cut them back in winter, spring, or summer and still get some blooms.