As I wander around my yard, I am seeing many flowers that have bloomed and are now starting to look "dead." They are actually ready to go to seed. So I pinch off the spent flowers or "deadhead" to cause the plant to flower again. Deadheading is very simple. As plants fade out of bloom, pinch or cut off the flower stem just below the spent flower and just above the first set of full, healthy leaves. Repeat with all dead flowers on the plant. The plant will flower again in a week or two. Most annuals and many perennials will continue to bloom throughout the growing season if they are regularly deadheaded.
The plant's purpose is to seed and reproduce so when you pinch off the spent flowers, it will re-flower to produce more seeds. I cut or pinch off "dead" flowers on snapdragons, dianthus, violas, pansies, roses, and sometimes columbine. Other plants that will re-flower with this process are bleeding heart, phlox, delphinium, lupine, sage, salvia, veronica, Shasta daisy, yarrow, and coneflower to name a few. I usually let them seed out after one deadheading, but this can be done more than once during a growing season. I spread the seeds after the second flowering after the seeds pods have dried on the plant so they will return next year in more abundance.
Although some people might consider this to be a tedious task, I enjoy being in my yard and “communing” with my plants. I encourage you to get outside and extend your summer flowering with deadheading!