
Photo: Jean-Pol GRANDMONT, CC BY-SA 3.0 · source
Pruning guide · Conifer
Western red cedar: when and how to prune
Thuja plicata
Western red cedar: as a hedge or grown freely, prune in May–June and August–September.
| Pruning months | May–June and August–September |
|---|---|
| Nesting season (15 March–15 August) | Take care in May–June and August |
| Native to Belgium | No, planted |
| Poisonous to people and pets | Yes, take care with children and pets |
Western red cedar: when to prune it?
Trim a hedge in May–June and late August, by mid-September at the latest. Check first that no birds are nesting.
What else to prune in those months? May · June · August · September
Western red cedar: how to prune it?
- Only cut into the green. It tolerates pruning better than most conifers, but a bare, brown patch fills in slowly, if at all.
- Keep the hedge slightly narrower at the top than at the bottom, and cut back the top as soon as it reaches the height you want.
- A free-standing tree needs no pruning; leave the lower branches.
How much to cut, and how often?
- Trim a hedge once or twice a year, after the first flush of growth (late June) and, if needed, in late summer. Check first that no birds are nesting.
- Most conifers do not regrow from old, bare wood. So never cut back into the brown part (exception: yew).
What does it mean for wildlife?
- Pruning in May–June and August can fall in the nesting season (15 March–15 August). Check carefully for nesting birds first: disturbing an active nest is against the law.
- A dense hedge gives birds a place to nest and shelter, and hedgehogs take cover underneath. Leave some leaves at the base.
- Prunings can go on a dead hedge or brash pile in a corner of the garden: shelter for hedgehogs, wrens and insects.
Common mistakes
- Clipping without first checking for nesting birds.
- Cutting back into bare brown wood: it will not regrow from there.
- Letting the hedge grow wider at the top than at the bottom: the base then goes bare.
Caution: Check first that no birds are nesting, and wear gloves: the sap can irritate the skin. Western red cedar is poisonous: wear gloves and keep clippings away from children, pets and livestock.
Nearby: related pruning guides
Similar to: Difference from Lawson cypress · Difference from northern white cedar
Plant profile: Western red cedar · Pruning calendar and basic rules
This guide is compiled from the Bladwijzer plant profile and pruning calendar.