Answer: Whew! A big project for a small site! First of all, a survey of the plants: peonies object to transplanting, and are often set back several years by the process. If you must move it for the design to work, do so as soon as possible. Your rose is better off being transplanted as a youngster than as a well-established shrub. The others you mention can be transplanted any time this spring or summer. Start with the level that will contain the peony and rose, and work around it as best you can, or leave it til next spring if that works better. Your choice of cedar boards is a good one, since they are rot-resistant. Support them with pegs driven deeply into the soil. You can use sections of cedar planks as stepping "stones" or paths as well. You can avoid severe compaction by moving the planks around to accomodate annual plantings year after year.
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