I purchased 6 Rose of Sharon bushes this summer. They were in 5 gallon buckets and were approximately 3 feet tall with plenty of leaves and in full bloom. I planted them side by side like a hedge. Over the next month, they began dropping their leaves and blooms. Is this normal? It is now the middle of September and I live in Zone 5. Do I need to cut them back, or do I just leave them be? They are Lavender Chiffon and Blue Chiffon.