Lavender bushes produce most of their tender green growth on the tips of old woody stems. Failure to prune the bushes regularly results in shrubs with little foliage. Unattractive woody sections begin to appear, especially at the centre of the plant. New green growth rarely occurs on the lower portion of the stems. Reviving the bush entails trimming the woody growth while leaving behind enough green stem tips to allow further leafing out.
Cut off the flowers after they finish blooming. Trim the woody stems back to the topmost green growth.
Prune lavender bushes in the fall. Remove up to one-third of the new growth from the preceding spring and summer. Avoid cutting into the woody stems, as these do not produce new growth.
Prune dead woody stems early in the following spring as the growth cycle resumes. Cut off these stems at the points where they emerge from the base of the plant. Remove no more than one-third of the old stems.
Remove one-third of the new growth again the following fall. Cut off any stems that produced no new green growth over the summer months.
Trim the woody stems again the following spring. Cut off only those stems that have produced no new green growth.
Lavender bushes may require replacement if more than half the growth has become old and woody.
Too much water kills a lavender bush. Over-fertilisation prevents lavender from flowering.