I need some advise with a new poolside garden I planted 4-5 months ago. Many of the plants, specifically the Liatris Kobold, Monard and Joe Pye weed is tipping over and making the garden look sloppy. They are planted on a slight slope. I'm not sure if its because the roots are still young and can't support the entire plant at this point or what? The plants look healthy otherwise. Any advise or answers would be very helpful