Should you prune lavender before winter? One mistake can kill the whole plant

Lavender can be lightly trimmed after flowering, but cutting it too hard before winter may put the whole plant at risk. The key factors are timing and the amount removed.

The Garden Beds portal recommends removing spent flower heads and overly long shoots, then gently rounding the bush. Done in late summer or very early autumn, this helps lavender stay dense and slows the process of becoming bare and woody. The plant needs several weeks after cutting to heal and prepare for dormancy.

Once autumn is well advanced, nights are cooling and frost may arrive soon, gardeners should stop shaping the plant. They can remove dry flower heads or broken branches, but should leave major pruning until spring. Strongly cut lavender is more vulnerable to frost, cold winds and moisture because much of its green growth has been removed. Pruning can also encourage fresh shoots that will not harden before temperatures fall below zero. The article advises removing no more than about one-third of the green growth before winter.

The woody part of the plant should not be cut. Lavender recovers poorly from old brown stems, and branches or the entire plant may fail to regrow after such pruning. Cuts should always leave green, leafy growth below them. Regular light trimming is safer than trying to rejuvenate a neglected, heavily woody bush in one operation.

Moisture can be as dangerous as cold. Lavender prefers sun and well-drained soil, while waterlogged roots may rot. Gardeners should avoid thick, moisture-holding mulch and should not cover the centre of the bush. Potted lavender is more exposed because its roots are surrounded by cold, so containers should be moved near a wall, under cover or to another sheltered place.