My landscaper planted about 20 PW Supertunia Vistas in my annual bed. They looked great for 1 month and now they are dropping like flies. They get watered almost every day, water soluble fertilizer every 1-2 weeks on top of slow release already in the soil. They are in a nice sunny spot with 0 shade. I pulled one of the dead ones out and the root ball came out in the perfect shape of the nursery can. Could this be a result of root bind???