Answer: Although these plants need even moisture, they also need a well drained location or the roots may rot. This is a fine line in selecting the right planting spot. Based on your description, I would suspect that the location is too wet. In my experience, these plants do much better in cool summer areas such as the mild climate of the Pacific Northwest (as you know, it wilts at noon time on warm summer days; partial filtered shade may help somewhat with this) and that is why they are not commonly grown in the MidAtlantic. When happy, the clumps expand rather quickly.
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