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Pruning guide · Climber
Mountain clematis: when and how to prune
Clematis montana
A mountain clematis doesn’t need pruning; if it has to be kept smaller, prune straight after flowering, in June: cut overlong stems back to within its allotted space and remove dead, tangled stems.
Mountain clematis is a very vigorous climber that covers a wall, pergola or old tree with hundreds of white or pink flowers within a few years. It flowers on last year’s wood: in winter the flower buds are already on the stems. That is why you prune it, if needed, straight after flowering. Many gardeners simply let it grow. The work is mainly keeping it out of gutters and roof tiles, and stopping it from becoming a heavy, tangled mass.
| Pruning months | June |
|---|---|
| Nesting season (15 March–15 August) | Take care in June |
| Flowering | May–June |
| Good for bees, butterflies and birds | Yes, for bees |
| Native to Belgium | No, planted |
| Poisonous to people and pets | Yes, take care with children and pets |
Mountain clematis: when to prune it?
Prune straight after flowering, in June. It then has the rest of the summer to make new stems that will flower next spring.
Never prune in winter or early spring: you would cut off that year’s flower buds.
Cut away stems growing into a gutter or under the roof tiles as soon as you see them.
What else to prune in those months? June
Mountain clematis: how to prune it?
- After flowering, cut stems that reach too far back to within the space you allow it, just above a few leaves.
- Carefully remove dead and tangled stems, so it doesn’t become a heavy, matted mass that weighs down the support or the tree.
- Clear it from gutters, roof tiles and around windows, far enough back to stay clear all summer.
- A neglected plant can be cut back hard after flowering, but it doesn’t always regrow from very old wood. Ideally spread such rejuvenation over a few years.
- Wear gloves: all parts are poisonous, and the sap can irritate the skin.
How much to cut, and how often?
- Often nothing: in an old tree or over a shed it can grow freely.
- If it has to be smaller, as much as needed straight after flowering, and for a neglected plant spread over a few years.
What does it mean for wildlife?
- June falls in the nesting season (15 March–15 August). Blackbirds, dunnocks and wrens like to nest in a dense clematis on a wall or in a tree: look carefully first, and spare an active nest until the young have fledged.
- The open flowers with their ring of yellow stamens feed honeybees, bumblebees and hoverflies in May–June.
- A dense mass of stems is also a winter shelter for small birds and insects. So don’t cut it bare every year.
- It is a non-native, but it doesn’t run wild here. If you want a native climber for wildlife alongside it, choose honeysuckle or ivy.
Common mistakes
- Pruning in winter or early spring, so the flowering is lost.
- Letting it grow for years into the gutter and under the roof tiles.
- Cutting an old plant back to bare wood in one go, so it doesn’t sprout again.
- Working in the sap without gloves.
Caution: Never prune in winter or early spring: you would cut off this year’s flower buds. Mountain clematis is poisonous: wear gloves and keep clippings away from children, pets and livestock.
Nearby: related pruning guides
Plant profile: Mountain clematis · Pruning calendar and basic rules