Answer: It's usually safe to cut back flowering shrubs immediately after they've finished flowering. However, pruning encourages new growth, and done this late in the season may produce new shoots that are tender and susceptible to dieback during winter weather. I'd suggest pruning in the dormant season (late winter to early spring) to allow the spring flush of growth to fill in pruned areas. Your plant will produce new flower buds along with new stems and should bloom right on time. If you trim the stems and branches back by 1/3, you'll force growth all over, including latent buds on the lower trunk of the plant.
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