I have an echinacea plant in my back garden. It is in a nice shady place and it hasn't quite finished flowering. What do I do with it when it does finish? Will it grow again next season? It is about 3 to 4 feet high. Do I cut it down? I have harvested the dead heads of the flowers and put them away. When do I reset them, and is there anything I have to do to make them take?