Certified GKH Gardening Expert
My research showed you can prune them in June, after flowers fade. Remove dead or diseased branches first, cutting them back to their point of origin. Then cut back any stems that disrupt the natural balance. Cut them back to their parent stems. Continue until all sides are even.
Always disinfect your pruning shears between cuts with a 10 percent chlorine bleach solution. Reduce amount of water after pruning.