Prune Hydrangea Bushes at the Right Time

Blushing Bride is a bigleaf hydrangea, so it should be pruned in summer, after it blooms. In less acidic soils, it blooms pink. To enhance the pink color, use horticultural lime.

When do you prune hydrangeas? Well, it depends.

Some hydrangeas bloom on current season’s growth and should be pruned in late winter or early spring, before the shrub begins active growth. These include several varieties that have become quite popular: Limelight, Quickfire, Burgundy Lace, as well as the classic “snowball” types, such as Annabelle. Another one that can be pruned in late winter is the PG or PeeGee, which produces creamy white flowers in late summer that age to rosy pink. Botanical names that will help identify the winter-pruned varieties: Hydrangea arborescens and H. paniculata. For more on this topic, read Early Season Pruning.

The Limelight hydrangea blooms on new growth, so it should be pruned in late winter, before new growth begins. Although the florets look similar to those of bigleaf hydrangeas, Limelight has teardrop-shaped bloom clusters and blooming starts later in the summer.

Most of the other hydrangeas should be pruned in summer, once they have finished blooming. If you were to prune them in early spring, you can cut off the dormant flower buds. By pruning after they bloom, you allow them time to set buds for the next year. Oakleaf (H. quercifolia) and bigleaf hydrangea (H. macrophylla), including Nikko Blue and all the other pink- and blue-flowering cultivars, bloom from buds set the previous year. If they need pruning to maintain size or shape, do it in the summer, preferably before August. The so-called ever-blooming hydrangeas, such as the Endless Summer and Blushing Bride, should be treated the same. These bigleaf hydrangeas are unique in that they bloom on old wood and new wood.

Blue Billow is another hydrangea that should be pruned in summer, after it has finished blooming. To enhance the blue color, use a soil acidifier. To learn more about why hydrangea color, read the article Growing Blue Hydrangeas.

If you don’t know what kind of hydrangea you have, here are some tips:

• If it blooms blue, it’s a bigleaf hydrangea and should be pruned in late summer, as necessary.
• If it doesn’t have blue flowers and it blooms later in the summer, it’s probably a good candidate for late-winter pruning.

Still not sure? Ask a good gardener in your neighborhood to help identify your shrub. Another option is to take a photo or bring a sample to a good garden center in your area. You can also e-mail one of our in-house gardening experts here at Gardener’s Supply.