I planted pink lightning ajuga about a month ago in a shady area under maple trees. I already had some other ajuga not far from it (I think the other one is Caitlin's Giant) and that one is doing just fine - it's been there for about 2 years now. But this pink lighting has developed brown spots on it. When it was brand new, I watered it regularly but have not done so for the past week (it's rained once in that week). Does it need more water? Did I overwater it earlier? Something else going on? It's not wilted, I don't see any bugs (though I realize that might not mean much!) or anything else causing this. Ideas?