Most of the Coreopsis Fell Over

I was out of town for a week and during that time most of my lance-leaf coreopsis flopped over. Last year I started these from seed, and because of continual dead-heading there were flowers all the way into November. So I’ll cut these plants back hard now and see if they bounce back by fall. Once it’s cleaned up, I’ll return with some ideas on why this happened in the first place.