Answer: These perennials do become nearly woody enough to be considered shrub-like. Cut them back quite hard in the late fall after bloom. In the spring, pinch them every other week or so as you would mums, or trim them back by about half in May and then pinch the tips or prune lightly every few weeks until the fourth of July. This should keep them growing bushy and dense with lots of blooms. If your plant is really just out of control, you could root some tip cuttings to replace it with. Do that in the spring to very early summer.
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