How to prune hydrangeas

Inspired by a helpful YouTube guide. We based this walk-through on the popular UK video "How to prune hydrangeas with the National Trust School of Gardening", from the National Trust's gardening channel. Their gardeners work with mature hydrangeas every season and the demonstration makes the difference between old and new wood very clear.

1. Identify your hydrangea type first

This matters more than almost anything else. The most common UK garden hydrangeas are mopheads and lacecaps — Hydrangea macrophylla — which flower on wood grown the previous year. Prune them at the wrong time and you remove those flower buds.

Panicle hydrangeas (H. paniculata, with cone-shaped flower heads) and smooth hydrangeas (H. arborescens, 'Annabelle' being the best-known) both flower on new growth produced in the current season. You can cut those back much harder without losing flowers.

2. Prune mopheads and lacecaps in early spring

Wait until you can see fat buds breaking into life on the stems — usually March or April, though this varies by year and by how sheltered your garden is. Cutting in late autumn or winter risks exposing fresh cuts to frost before the plant has a chance to seal them.

Leave the old flower heads on through winter — they give some frost protection to the buds just below them, and they look reasonable in a wintry garden. Remove them in spring, cutting just above the first strong pair of buds below the old flower stalk.

3. Remove completely dead stems from the base

While you have the secateurs out, look for stems that are clearly dead — grey, brittle, no sign of buds anywhere along their length. Cut those right back to the base. They will not produce flowers and they are wasting space.

On an older plant, there may be a tangle of old woody stems crossing each other in the middle. Take out the weakest and the most congested. You are aiming for an open, well-spaced structure where light and air can circulate.

4. Cut panicle and smooth hydrangeas harder

Unlike mopheads, H. paniculata and H. arborescens respond well to a firm cut each year in late winter or early spring. Cut all the previous season's stems back to a framework of two or three buds from the base — or back to the main framework if the plant has grown into a shrub rather than a near-ground-level clump.

This hard pruning encourages strong new shoots and bigger flower heads. Left unpruned year after year, these types produce thinner stems and smaller flowers.

5. Feed after pruning

Once you have finished cutting, give the plant a dressing of general-purpose fertiliser around the root zone and work it in lightly with a fork. Follow with a good layer of garden compost or bark mulch to retain moisture through the growing season.

Hydrangeas are thirsty shrubs. Mopheads in particular will wilt dramatically in dry spells — deep watering two or three times a week in summer is better than a light daily sprinkle.

6. Renovating a neglected hydrangea

If you have inherited a large, leggy plant that has never been pruned, do not try to sort it all in one go. Take out one in three of the oldest stems in the first year, another third the following year, and the rest after that. By the third year the plant will have renewed itself without a complete loss of flowers in the meantime.

That said, mopheads are remarkably forgiving. A hard cut to near ground level will usually recover — it just means sacrificing a year of flowers while the new growth establishes.

When to call a handyman

Hydrangeas are generally a job homeowners can tackle with decent secateurs and a bit of confidence. That said, if the garden has got on top of things generally — overgrown shrubs, a lawn that needs work, or a whole list of outdoor jobs accumulating — Richard can help you work through it all in a sensible order.