Photo: Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database / USDA SCS., Public domain · source
Pruning guide · Shrub
Alder buckthorn: when and how to prune
Frangula alnus
Prune alder buckthorn only when necessary, in winter (November–March), and ideally before mid-March: now and then remove an old or leaning stem at the base, or coppice a shrub that has grown too big.
Alder buckthorn is a native, airy shrub of 2–5 m for moist, acid soil. It doesn’t stand out much, but it is a top plant for wildlife: it flowers from May into September for bees and bumblebees, bears berries for birds, and its leaves feed the caterpillars of the brimstone butterfly. It hardly needs pruning. Leave its airy, natural shape, and only step in if it grows too big or bare.
| Pruning months | November–March |
|---|---|
| Nesting season (15 March–15 August) | Take care in March |
| Flowering | May–August |
| Good for bees, butterflies and birds | Yes, for bees, butterflies and birds |
| Native to Belgium | Yes |
| Poisonous to people and pets | Yes, take care with children and pets |
Alder buckthorn: when to prune it?
Prune in winter, November–March, and only when necessary.
Finish before mid-March: after that, birds nest in the shrub, and brimstones lay their eggs on the young leaves.
Dead, diseased and broken branches can be cut out all year round.
What else to prune in those months? January · February · March · November · December
Alder buckthorn: how to prune it?
- Keep its airy, natural shape: don’t clip it all over.
- Now and then saw an old or leaning stem off at the base, so young stems can come through.
- If the shrub grows too big or bare, coppice it to 20–30 cm above the ground. It regrows readily.
- In a field hedge, coppice the alder buckthorn along with the rest in turn, a different stretch each time.
- Wear gloves: the fresh bark in particular is poisonous, and don’t give the prunings to animals.
How much to cut, and how often?
- Little: an old stem every few years, or coppicing every 8–10 years.
- A shrub that is allowed to grow freely flowers and fruits the most.
What does it mean for wildlife?
- Prune before mid-March, before the nesting season (15 March–15 August): songbirds such as the garden warbler and blackcap nest in alder buckthorn.
- Alder buckthorn is the food plant of the brimstone: in April–May the females lay their eggs on the young leaves. If you prune in spring, you cut them off too.
- The small greenish-white flowers from May to September are one of the longest-lasting meals for bees and bumblebees.
- Blackbirds, thrushes and robins eat the black berries. For people, pets and livestock they are poisonous.
Common mistakes
- Pruning in spring, with the brimstone’s eggs on the young leaves.
- Clipping the shrub all over, so it loses its airy shape and many flowers.
- Pruning for no reason: it rarely needs it.
- Giving the prunings to horses, sheep or rabbits.
Caution: Prune preferably before mid-March: after that, birds nest in the shrub and brimstones lay their eggs on the young leaves. Alder buckthorn is poisonous: wear gloves and keep clippings away from children, pets and livestock.
Nearby: related pruning guides
Similar to: Difference from common dogwood · Difference from buckthorn
Plant profile: Alder buckthorn · Pruning calendar and basic rules