Don’t cut into the brown, woody part of the plant.
Between the end of July and the beginning of August, when the lavender has mostly finished blooming, it’s time to bring the pruning shears! If you cut back the flower stalks at this time, you can hope for another flowering in early autumn. Although this second bloom is expected to be weaker, not only will you enjoy the sight, but the insects will also appreciate the food source.
Do not wait too long to trim the plant back: the less the lavender has finished blooming, the greater the chance of a second bloom. On the other hand, with timely pruning, the plant still has time to become strong until winter.
When pruning in the summer, remove only those flower stalks that are almost bare. Place the pruning shears directly above the leafy part of the plant. While pruning shears are sufficient for some plants, hedge clippers can be used for older ones. You can leave a few cm of the flower stalks, preferably do not cut too deeply into the leafy part.
Lavender should be pruned back to a greater extent in the spring, when no more frosts are expected. This time usually comes in April, before the new shoots appear. Lavender should not be cut back to a large extent at the end of summer or in autumn, because this will excessively weaken the plant for winter. It is important not to cut into the old, woody, brown part. In this case, your plant will only rarely sprout again later.