I am seeing some of that on mine too, but I think it is drought conditions as the culprit. I have been trying to water regularly, but the heat dries the dirt so quickly that it seems like an endless battle to hydrate the roots. It could be lack of N, too, as so many of mine have been blooming not too long ago. I will be adding N fertilizer to them tomorrow to see if that improves their appearance. Does epsom salt help, too?
