I am not talking about the Grateful Dead but us gardeners who religiously go around the garden each day decapitating plants.
Many plants will bloom throughout the seasons if the dead flowers are snipped. Many of the new petunias are self-cleaning and do not need to be snipped unless you prefer for looks. During the season, prune from the bottom and the middle on these super powered petunias to keep them going until the end of the season. Make sure you do not let coleus go to flower or they will stop spreading. Geraniums need to be picked off when done and then the brown stems need to be snipped off (you will get many more blooms if you do this). Don't forget, all annuals need to be fed. I use a super bloom formula for all annuals - not perennials, about every two weeks.
Coneflowers will rebloom if snipped, daylilies, most will not, some phlox will rebloom, like Blue Paradise, May Night Salvia will rebloom, nepeta will rebloom, Gaillardia will rebloom, Becky Shasta will not rebloom (at least in my area). Roses need to be consistently pruned to develop new growth, except for the Knockouts because they will bloom no matter what you do, except they will look messy. I just performed surgery on my Rainbow Knockouts today so they will look beautiful for the rest of the season because they will bloom until November. Take no prisoners if you are pruning a large Knockout. I shaped them, cut out wayward stems and will fertilize them again (every six weeks - stop in August).
Don't be afraid to prune/deadhead, it will keep your garden looking beautiful!