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From Gardener's Supply (www.gardeners.com)

When to Prune Hydrangeas

By David Grist, Former Employee-Owner

Blushing Bride is a bigleaf hydrangea (Hydrangea macrophylla), 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.

If it blooms in late summer

Some hydrangeas bloom on new 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 classic PG or PeeGee, which produces creamy white flowers in late summer that age to rosy pink.

The botanical names help identify the winter-pruned varieties: Hydrangea arborescens and H. paniculata.

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.

If it's blue, or blooms in summer

Most of the other hydrangeas should be pruned in summer, once they have finished blooming. Most of these bloom on what's called "old wood" — growth from the year before. If you prune them in early spring, you risk cuting off the dormant flower buds. By pruning right after the blooms have faded, you allow the plant 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 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 should be pruned in summer, after it has finished blooming. To enhance the blue color, use a soil acidifier (garden sulphur). To learn more about hydrangea color, read the article Growing Blue Hydrangeas.

How to Tell the Difference Between Hydrangeas

Common names	Botanical name	When to prune
panicle hydrangea, PG hydrangea,	Hydrangea paniculata	late winter, before growth begins
bigleaf hydrangea, mophead, hortensia, lacecap	Hydrangea macrophylla	after bloom in summer
mountain hydrangea, lacecap	Hydrangea serrata	after bloom in summer
smooth hydrangea, annabelle, snowball	Hydrangea arborescens	late winter, before growth begins
oakleaf hydrangea	Hydrangea quercifolia	after bloom in summer
climbing hydrangea	Hydrangea anomala subsp. petiolaris	after bloom in summer

Presented by Laura from Garden Answer

More ways to tell what you have

If it blooms blue, it's a hydrangea that should be pruned in late summer, as necessary.
If it doesn't have blue flowers and it blooms later in the summer (after July 4), 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.

Last updated: 2/11/19