Answer: Plumbago tends to develop powdery mildew late in the growing season, but it doesn't usually cause too many problems for the plant. To both keep the plant size under control and to remove the diseased parts, cut the plant back hard in late winter. (To within a few inches of the ground.) You can do this every year. If the plant has become very large, you can dig and divide it, then replant a smaller portion in the original hole. Dig and divide after you've cut it back (for ease in handling). Best wishes with your garden!
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