Lavender

I usually do mine after the main flowering time. I trim them back to the shape I want.

I trim them when the flowers have finished, dead-heading, then give them a slightly harder prune in early spring.

according to Gardeners world i was watching the other day the ideal time to prune is just before the kids go back to school, so now really - as traditionally the lavender blooms were havested this time of year for drying out. and apparently it is the best time to do it. and you should cut back to just below where the flower stem starts, making a good over all shape but never cut into old wood as this will kill the plant.