I live in Zone 5 (northern Kansas) and have some tithonia in a container. They were doing very well and are about three feet tall right now. We had some recent heavy rains followed by some hot days and now the lower leaves are turning yellow and the plants look as though they are wilting. I am afraid to water them. Is this due to the rain or some other cause? Is there anything I can do to recover my plants? Thanks for any help you can provide.