Hello, I have dwarf nandinas with leaves that are starting to turn brown and stiff. I just watered them last week and I read online that I can over water them? Would this be the issue? I didn't water them more than usual, but maybe I did. How can I bring these back? I live in a hot Texas heat, but I can't imagine that being the issue. One of the photos is of one nandina still doing well. Thank you for the help!