Removing Spent Flowers/Deadheading
Despite the rather ominous sound of the term, "deadheading" or removing the spent flowers of your annual and perennial flowers is a good way to trick those plants into producing more flowers over an extended period of time. In the case of annuals, this might mean a bloom period that stretches from spring until frost. In the case of perennials, it may mean extending by several weeks to a month the normal length of time that flowers are present.
Deadheading is based on the natural principle that a plant produces a flower, so that this will be pollinated and produce a seed, thereby guaranteeing the survival of the species. By removing spent flowers, we can convince the plant that its mission is not quite complete.
Some flowering plants are self-cleaning, like impatiens, thus it is not necessary to remove their withered blooms, but most annuals benefit from deadheading as this process encourages fresh new growth and new blooms, like pansies, salvia, and zinnias.
Although deadheading may extend the bloom period for perennials, there are reasons not to remove the spent flowers. The dried flowers and seed heads of some species may provide added structure and contrast to the summer garden, as well as be of interest in the winter. Additionally these seed heads can serve as a valuable food source for birds. The purple coneflower is an example, as is sedum. With a plant such as a continuous blooming rose, you should stop cutting spent flowers in September, allowing them to wither and dry on the bush. This signals the plant that its mission is indeed complete, and that it should ready itself for the coming winter. Lastly, donít cut off all the dead flowers if you want to save some seed from a favorite plant, rather let the seeds form, mature and dry on the plant before you collect and store them. To decide which plants to deadhead and which not in your garden, experiment. Call the County Extension Office if you have any questions about the characteristics of a particular flower.