Pruning your hydrangeas

A Bigleaf Hydrangea just before pruning

Yes! The night frost has finally passed and hydrangeas are already pushing out large green buds. Time to prune. But how exactly does it work again? Some hydrangeas welcome a firm cut. Others will quietly refuse to flower if pruned too enthusiastically. The difference lies in one simple question: does the plant flower on old wood or on new growth?

That distinction makes all the difference.

Prune lightly: Hydrangea macrophylla

Hydrangea macrophylla (bigleaf hydrangea) forms its flower buds in late summer on stems produced the previous year. Those buds remain through winter. The dried flower heads are best left in place during the colder months. They provide a little extra protection for the upper buds and add winter structure to the garden.

In spring, remove only the spent flower head, cutting just above the first pair of healthy, well-developed buds. Avoid cutting lower down the stem, as this may remove the flowers for the coming season. If the shrub becomes congested, one or two of the oldest stems can be removed at ground level to encourage renewal.

When in doubt, cut less.

The same Hydrangea in May, with butterflies finding protection as the evening sets in

Prune firmly: Hydrangea paniculata and arborescens

Hydrangea paniculata (panicle hydrangea) and Hydrangea arborescens (including ‘Annabelle’) flower on new growth produced in the current season. These types can be cut back confidently in early spring. Reducing them to 20–40 centimetres above ground level encourages strong new shoots and sturdy flower heads later in summer.

Without pruning, they will still bloom, but often on longer, weaker stems.

In their case, pruning strengthens rather than harms.

If unsure, a quick visual check often helps

Rounded leaves and colourful summer flowers usually indicate macrophylla.

Conical flower heads suggest paniculata. Large white domes on softer stems often belong to arborescens. If uncertainty remains, prune lightly the first year and adjust the following season.

The same Hydrangeas in August, in their full blue beauty

In short…

Treat all hydrangeas the same, and disappointment is likely.

Know which type is growing in the garden, prune accordingly, and those green buds will reward your efforts with flowers.

Take me to the next journal post!