No doubt you've heard that a well-designed garden should include plants prized for their striking foliage, as well as some that produce fall color or berries, and others that provide good structure in winter. But lets face it: most of us want flowers. Lots of them. All the time. That's where the plants listed below come in. They'll churn out blooms for weeks on end this summer. In most cases, you can harvest armloads to fill vases or give away, and still have plenty left to enjoy in your garden beds long past Labor Day.