Answer: If your plants are old and leggy but healthy, you can cut them back quite a bit without endangering them, perhaps even by half. You will achieve a more natural shape by cutting entire branches off deep within the plant rather than by shearing the exterior, but either method can be used. You will find that they regrow fairly quickly because they have such large root systems in relation to their trimmed tops. If they begin to look leggy as they regrow, simply nip a tip off here and there to force additional branching. Do make sure, however, that they are mulched and receive adequate nutrients and water for the entire season afterwards. Finally, in some cases these plants will grow with a very airy, almost tiered, look because they are in deep shade and are stretching to maximize the available light. If this is the case, they may not fill in and be dense as you would like no matter how they are pruned. Good luck with your pruning!
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