Answer: Based on your description I'm not exactly sure what the problem is, but very often this plant "melts" in hot humid weather. The result is quite messy and could just about be described that way. The solution is to trim back the affected bits and wait for cooler weather and lower humidity. Avoid getting water on the foliage when you water and try to plant it in a spot with good air circulation. The larger leafed form (sometimes called "Helene von Stein") seems to handle humidity better than the usual variety, so you might want to see if anyone in your area has had better luck with that one.
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