Photo: Eric Hunt, CC BY-SA 4.0 · source
Pruning guide · Shrub
Ninebark: when and how to prune
Physocarpus opulifolius
Prune a ninebark after flowering, in late June–July: every year saw a few of the oldest branches off at the base, and cut flowered branches back to a strong, young shoot.
Ninebark (Physocarpus opulifolius) is a tough, easy shrub of 2–3 m, best known in gardens for its forms with dark purple or golden leaves. In June it flowers with rounded white flower heads, followed by inflated, reddish fruits. It flowers on last year’s wood. Pruning is mainly about renewal: young branches have the finest, most brightly coloured leaves. Take out some old wood every year and you keep the shrub young, colourful and within bounds.
| Pruning months | June–July |
|---|---|
| Nesting season (15 March–15 August) | Take care in June–July |
| Flowering | June |
| Native to Belgium | No, planted |
Ninebark: when to prune it?
Prune after flowering, in late June–July. The shrub then has the rest of the summer to make new branches that will flower next year.
A neglected shrub can also be cut right back in late winter, but then it won’t flower that year.
Don’t prune in winter if you want flowers: it flowers on last year’s wood.
Ninebark: how to prune it?
- Every year, saw a few of the oldest branches off at the base. You can recognise them by the bark peeling off in long strips.
- Cut flowered branches back to a strong, young shoot lower down the branch.
- A neglected shrub can be cut right back to 20–30 cm above the ground. It regrows vigorously, with brightly coloured leaves.
- On coloured forms, cut out branches with plain green leaves back to where they start.
- Trim a ninebark hedge into shape after flowering, slightly narrower at the top than at the bottom.
How much to cut, and how often?
- Every year: about a fifth of the oldest branches, and the flowered branches.
- A neglected shrub: back to 20–30 cm in one go, and a year without flowers.
What does it mean for wildlife?
- Late June–July falls in the nesting season (15 March–15 August). Blackbirds and dunnocks like to nest in a dense ninebark: look carefully first, and spare an active nest.
- The rounded flower heads in June attract bees, bumblebees and hoverflies. The fruits hang on into winter.
- The peeling bark of old branches gives small insects a hiding place. Leave a few old branches in a corner where they don’t get in the way.
- It is a non-native from North America. Combine it with native shrubs such as guelder rose or wild privet, which also feed caterpillars and birds.
Common mistakes
- Pruning in winter, so that year’s flowers are lost.
- Never removing old branches, so the leaves become dull and small.
- Leaving the green branches on coloured forms.
- Pruning without first checking for nests.
Caution: Do not prune in winter if you want flowers: it flowers on last year’s wood.
Nearby: related pruning guides
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