I have three mexican bush sages in a planter in my front yard. I planted them last spring and they have been doing really well until just recently. All fall, winter, and spring they absolutely thrived. The grew really fast, had big beautiful purple flowers from probably February through May. Then in June the flowers started turning white and the leaves started turning yellow. The plant has thinned out significantly and just looks sick. I don't really know what has changed other than it got hotter. It does get pretty hot in Texas in the summer (I'm in Austin) but I water them every week. Am I doing something wrong? Do they have a disease? is this just part of how the plant works? Help me out here!