Pruning
Lavender
Keeps it compact; bare wood with no green shoots below the cut will not regrow.
When
After flowering (late summer)
How
Straight after flowering, cut back hard into the soft leafy growth, taking off about a third of the foliage. Do not cut into the bare wood unless green shoots are already showing below the cut, because a cut with no shoots below it will not regrow.
Notes
A second light tidy in spring.