There are some plants in the garden that seem to thrive no matter how hot and humid August gets. My zinnias are one. Those flowers just never stop! But it seems like most of my perennials wilt during the overbearing weather of late summer, a lot like we as humans do. Those days when you just step outside and break a sweat can be tough. The weather completely zaps your energy before you really even get anything done. So when my coneflower quit...