How to prune hydrangea

How to prune hydrangea

1. 01

   Which hydrangea is this page for?

   Panicle hydrangea (Hydrangea paniculata) and smooth hydrangea (Hydrangea arborescens) are pruned differently, so do not use this advice for them.

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   Do not cut the whole plant down, because that removes the flowers for the summer.

   This page covers bigleaf hydrangea (Hydrangea macrophylla), the mophead and lacecap types, which the RHS says flower from mid to late summer on the previous year’s growth.

2. 02

   When and how much

   The RHS says most pruning is done in late winter or early spring. Leave the faded flower heads on the plant over winter, because they give some frost protection to the tender buds below.

   

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   In early spring remove them by cutting the stem back to the first strong, healthy pair of buds down from the faded bloom.

   Lacecaps are hardier. The RHS says their faded heads can be cut back after flowering to the second pair of leaves below the head, which stops seeds from forming and sapping energy from the plant.

3. 03

   Thin out old stems

   On an established mophead or lacecap, cut out one or two of the oldest stems at the base. The RHS says this encourages new replacement growth that produces more flowers.

4. 04

   What not to do

   Do not prune late in the season. Another source warns that late pruning removes next year’s buds and gives early August as the last safe date in its own climate.

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   Do not cut all the stems to the base unless the plant is overgrown or badly shaped. The RHS says this removes all the flowers for that summer and the new stems will not bloom until the following year.

   Winter injury is the most common reason bigleaf hydrangeas fail to bloom, so a bare spring is not always a pruning mistake.

5. 05

   Renovating an overgrown plant

   To avoid flower loss, spread drastic pruning over three or four years.

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   The RHS says established plants tolerate hard pruning in spring, but cutting back hard in one go is likely to reduce flowering for the next couple of summers.

6. 06

   Keep your tools clean

   Use clean, sharp bypass pruners and disinfect them between cuts to limit the spread of disease.

Common questions