Japanese spiraea: when and how to prune

Spiraea japonica

Prune a Japanese spiraea in March, before the new shoots appear: cut all stems back to 15–20 cm above the ground, as it flowers on new wood.

Japanese spiraea is a compact shrub of 50–80 cm with pink to crimson flower heads from June to August, and coloured foliage in many varieties. It flowers on new wood: the flowers come on this year’s shoots. So you can cut it back hard every spring. With one pruning a year it stays attractive and compact for years; skip it and within a few years you have an untidy shrub full of dead wood.

Updated on 11 October 2026

Key facts
Pruning months	March
Nesting season (15 March–15 August)	Take care in March
Flowering	June–August
Good for bees, butterflies and birds	Yes, for bees and butterflies
Native to Belgium	No, planted

Japanese spiraea: when to prune it?

Prune in March, before the new shoots appear.

In summer, cut off the faded flower heads: it often flowers a second time.

Don’t cut it back hard in late spring or summer: you would cut off the flowering shoots.

What else to prune in those months? March

Japanese spiraea: how to prune it?

Cut all stems back to 15–20 cm above the ground, just above a few buds.
On older shrubs, also remove dead and thin stems at the base.
In July, cut off the faded flower heads just below the flower, for a second flush in August.
On varieties with yellow or orange leaves, cut out shoots with plain green leaves back to where they start.
Hedge shears are fine too: then cut the whole shrub low in one go, into a rounded shape.

How much to cut, and how often?

Every year all the stems, back to 15–20 cm above the ground.
On old shrubs, also a few dead or weak stems at the base.

What does it mean for wildlife?

March falls mostly before the nesting season (from 15 March). Hardly anything nests in a low spiraea, but take a look if you are late.
The flower heads in June–August attract bees, hoverflies and butterflies. Cutting off the faded heads gives a second flush, and so more food in late summer.
Aphids on the young shoots in May feed ladybirds and tits: don’t spray.
It is a non-native. Combine it with native plants that feed bees and butterflies, such as wild marjoram, red clover or, on acid soil, heather.

Common mistakes

Never pruning, so the shrub becomes untidy and flowers less.
Cutting it back hard in summer, so the flowering is lost.
Leaving the green shoots on coloured varieties, until they take over the whole shrub.
Only shortening the tips, so a bare tangle of dead twigs builds up at the bottom.

Nearby: related pruning guides

Plant profile: Japanese spiraea · Pruning calendar and basic rules