When to Prune Hydrangeas? Timing for Every Type

Step by step

1. 1

   Identify the type first

   Everything depends on the type. Panicle hydrangea has cone-shaped, elongated flower heads and stiff stems. Smooth hydrangea (like the Annabelle variety) forms big, rounded white flower heads. Bigleaf (macrophylla) has round balls or flat lacecaps in shades of pink, blue and purple, plus thick, fleshy stems.

2. 2

   Panicle and smooth - hard pruning in spring

   These two types flower on stems that grow in the current season, so you can cut them boldly. In late February or early March, shorten last year's shoots, leaving 2-3 pairs of buds above the woody base. Cut panicle hydrangea back to a low framework, and you can take smooth hydrangea down to 20-30 cm (8-12 in) above the ground.

3. 3

   Bigleaf - light tidying only

   Hydrangea macrophylla sets its flower buds in summer, on the current year's stems, and carries them through winter. So do not cut it back hard. Only remove the spent flower heads, cutting just above the first healthy pair of buds below the dried bloom, and take out dead and broken stems.

4. 4

   Cut above a pair of buds

   Hydrangea buds sit opposite each other in pairs. Make your cut about 1 cm above a chosen pair of healthy, plump buds. New shoots will grow from these buds, so a pair facing outward gives you a looser, better-lit crown.

5. 5

   Remove old and weak stems

   Whatever the type, remove dry, diseased, pencil-thin stems every year, along with any that cross and rub against each other. On older shrubs, cut 1-2 of the oldest, woodiest stems out at ground level. This pushes the plant to send up young, stronger shoots.

6. 6

   Never prune bigleaf in autumn

   This is the most common mistake. If you shorten a bigleaf hydrangea in autumn, you cut off the buds that were going to become spring flowers. Leave the dried flower heads on over winter - they shield the buds underneath from frost. Clear them away in spring, once the hard frosts have passed.

Why the type dictates the timing

Hydrangeas fall into two groups based on where they set their flower buds. Panicle (Hydrangea paniculata) and smooth (Hydrangea arborescens) hydrangeas bloom on new wood - the growth put on this spring. Even cut back low, they rebuild their stems and flower by summer.

Bigleaf (Hydrangea macrophylla) and oakleaf hydrangeas bloom on last year's stems. The bud you see in June formed the previous summer and overwintered at the tip of the stem. Any hard cut on such a stem removes a ready-made flower. Hence the simple rule: prune plants that flower on new wood hard in spring, and only gently tidy those that flower on old wood.

Climbing hydrangea and other exceptions

Climbing hydrangea (Hydrangea petiolaris) needs almost no pruning. Limit yourself to shortening shoots that stray beyond their support and removing dead twigs, ideally right after flowering. Pruning too hard will delay flowering by a year or two.

Among bigleaf hydrangeas there are also reblooming varieties that set buds on both old and new stems. They forgive small mistakes, because some flowers appear even after the stems freeze back in winter. If you are not sure which type you have, prune sparingly the first year and watch where the flowers appear.

How pruning affects flower size and color

Pruning alone does not change a bigleaf hydrangea's color - whether the flowers are blue or pink depends on soil pH and composition, not on your pruners. Hard spring pruning of panicle and smooth types does give you fewer but larger flower heads, because the plant channels its energy into a few strong stems.

For a dense shrub with many smaller blooms, prune these types more gently and leave more stems. While you are at it, feed hydrangeas in spring with a fertilizer for flowering plants and mulch the soil, because they cope poorly with dried-out roots.

Frequently asked questions