As we get passed the middle of August (arghh!!), it’s time to consider whether to deadhead or not. Deadheading is the practice of removing the spent flowers on plants – usually by snapping off a fading flower with your fingers or snipping off a stem with a bypass pruner.
Deadheading has two main purposes. First, because it prevents plants from setting and distributing seeds (their goal in life) it keeps them blooming longer. The second purpose is mostly aesthetic, to keep plants looking neater by removing the brown, crispy old blooms hanging on them.
For plants you do not want to set seed, you can keep on deadheading as long as you like. Many gardeners buy annuals, for example, as plants each spring and do not wish to collect seeds from them. So for plants like marigolds, snapdragons and petunias, you can continue to deadhead until you get tired of doing it. Or, if you want to collect some seeds, let a few plants go to seed and harvest those seeds for next year.
Perennial plants, such as roses, phlox, bee balm, delphinium and a host of others, don’t have the same single-season life cycle of annuals but they also benefit from deadheading—at least up to a point. As a plant starts to get past its peak bloom, look for spots where you can cut out the old growth, allowing room for side shoots to grow and new blooms to form. Unless you like the look of the seed heads, such as those on coneflowers or sedum, removing the old blooms neatens up the plant’s appearance. Most northern gardeners stop deadheading in late August or early September to give perennials a chance to prepare for winter.
Deadheading can be tedious, which is why many newer plant varieties are “self-cleaning.” New varieties in everything from bacopa to verbena have been bred to drop their flowers on their own and keep on blooming. If you are dead-set against deadheading, these are the plants to choose.
If you are interested in learning more about deadheading, Bonnie Blodgett has an excellent article on the whys of deadheading on her Blundering Gardener website. The University of Minnesota Extension has a great article on pruning perennials on its website, too.