Photo: Eric in SF, CC BY-SA 3.0 · source
Pruning guide · Shrub
Oakleaf hydrangea: when and how to prune
Hydrangea quercifolia
Prune an oakleaf hydrangea as little as possible, and only straight after flowering, in August or early September: remove dead and crossing branches at the base, and never shorten the tips.
The oakleaf hydrangea is a broad shrub with large, deeply lobed leaves, white flower panicles in summer, glorious autumn colour and cinnamon-brown bark in winter. It flowers on last year’s wood: the flower buds sit at the tips of the branches. Shorten the tips in autumn, winter or spring and you get no flowers. It naturally grows into a good shape and needs little pruning: taking out a branch at the base now and then is enough.
| Pruning months | August–September |
|---|---|
| Nesting season (15 March–15 August) | Take care in August |
| Flowering | July–September |
| Good for bees, butterflies and birds | Yes, for bees |
| Native to Belgium | No, planted |
Oakleaf hydrangea: when to prune it?
If needed, prune straight after flowering, in August or early September. It then still has time to make new tips with flower buds.
Never prune in autumn, winter or spring: you would cut off the flower buds at the tips.
Dead branches can be cut out all year round, back to living wood.
Oakleaf hydrangea: how to prune it?
- Remove dead, damaged and crossing branches at the base, not halfway.
- Too big? After flowering, take out one or two of the oldest branches at ground level, instead of shortening the whole shrub.
- If you want to get rid of the faded panicles, cut them off just below the panicle straight after flowering. You can also leave them: they dry beautifully.
- Never shorten the tips in winter or spring: that is where next year’s flower buds are.
- A shrub that is too big is often better off in a more spacious spot: it transplants well in autumn.
How much to cut, and how often?
- As little as possible: often nothing for years, apart from a dead branch.
- A shrub that is too big: one or two old branches at ground level a year, no more.
What does it mean for wildlife?
- August falls partly in the nesting season (until 15 August): before pruning, check that no birds are nesting in the shrub, and ideally prune after mid-August.
- Besides the large sterile flowers, the panicles also have small, fertile flowers that attract bees and hoverflies.
- The dry panicles and peeling bark shelter small insects and spiders in winter.
- It is a non-native of little value as a food plant for native caterpillars. Combine it with native shrubs for partial shade, such as hazel or guelder rose.
Common mistakes
- Shortening the tips in winter or spring, so there are no flowers.
- Trimming the whole shrub all over every year.
- Cutting branches halfway instead of at the base.
- Still pruning after early September, so there is no time left to form flower buds.
Caution: It flowers on the previous year’s wood: pruning in autumn, winter or spring removes the flower buds.
Nearby: related pruning guides
Plant profile: Oakleaf hydrangea · Pruning calendar and basic rules