Alder: when and how to prune

Alnus glutinosa

Alder is best pruned in November–March.

Updated on 11 October 2026

Key facts
Pruning months	November–March
Nesting season (15 March–15 August)	Take care in March
Flowering	February–March
Good for bees, butterflies and birds	Yes, for butterflies and birds
Native to Belgium	Yes

Alder: when to prune it?

During winter dormancy (November–March).

Prune while dormant, from November to March, but not in freezing weather.

What else to prune in those months? January · February · March · November · December

Traditionally managed by coppicing or pollarding, cut back every 5–10 years. Regrows readily.
Cut coppice low with a sloping cut, so that rainwater runs off the stool.
A free-standing tree needs little pruning: just remove dead and broken branches.

One pruning period a year: November–March.
Pollarding: every 3 to 7 years, cut all branches back to the head, in winter.
Can be cut back to just above the ground every few years and will then regrow.
Never remove more than about a quarter of the crown at once. Better a little every year.

Pruning in March can fall in the nesting season (15 March–15 August). Check carefully for nesting birds first: disturbing an active nest is against the law.
Host plant: caterpillars of butterflies or moths eat the leaves.
As a native plant, it feeds more insects than a non-native species.
Prunings can go on a dead hedge or brash pile in a corner of the garden: shelter for hedgehogs, wrens and insects.

Clipping without first checking for nesting birds.
Leaving a stub or sawing flush with the trunk: cut just outside the branch collar.

Caution: Freshly cut alder wood turns orange-red within minutes: that is normal and not a sign of disease.

This guide is compiled from the Bladwijzer plant profile and pruning calendar.