The “dog days of summer” often describe the hot weather near the end of July and through August. Many plants in the landscape are fading out of bloom and looking “less than best” at this time as well. A number of summer favorites are prime candidates for such treatment. Roses, all members of the mint family (including spearmint, peppermint, catmint, bee balm, agastache, etc.), most herbs (lavender, oregano, thyme, yarrow, Russian Sage, etc.), daylilies, Asiatic Lilies, peonies, carnations, ligularia, coral bells (Heuchera), foam flowers (Tiarella), Rhododendrons, azaleas, Campanula (Balloon flowers), Iris, Black-eyed Susans, columbine, hosta, bugloss, lilacs, spirea, dozens other perennials and flowering shrubs, and even many decorative grasses all benefit from proper deadheading. Rhododendrons and azaleas perform better after removing the spent flower heads too.
The list of benefits is nearly as impressive as the plants that respond positively to removing spent blossoms. A primary reason is mere aesthetics. While flowering shrubs and perennials are small, it’s fairly easy to snip off spent or fading flower blossoms with a hand pruner or simply snap them off with your fingers. It makes the plant appear “kept up” and more attractive.
Another major reason to deadhead is the plant’s health. Many flowering plants put a lot of energy into seed production after their flowers are pollinated. By removing spent blossoms, you avert that tendency toward plant growth instead of reproduction. Late in the growing season, it’s important that a plant store carbohydrates in its root system in order to survive winter dormancy. One way to increase plant vigor is deadheading, because energy otherwise spent making seeds is directed into preparing for “another try next year.” In the long-run, it really increases the amount of blossoms you get every year. By removing spent blossoms, you divert energy from seed production and promote stronger root and leaf development.
A secondary benefit of preventing seed production is that you don’t end up with new plant starts all over your landscape and lawn. This alone can be a valuable reason to remove fading flowers. I just had a customer ask me to take out her yellow clematis (Virginia Bower Vine) because the seedlings it produces every year are taking over her flower bed. It’s a beautiful vine, but it just isn’t worth fighting with it to prevent aggressive spreading! Many of our exotic weeds are landscape plants which escaped and now are wreaking havoc in the wild since naturalizing.
One way to spur tighter, more attractive growth is to cut back spent flowers. Light pruning of stem tips, such as takes place when you deadhead, can be considered a form of “heading back.” This landscape technique is used to covert a tall, leggy plant into a compact, bushier version of itself. Removing actively growing stem tips, interrupts the flow of auxin, a plant hormone that directs growth upward. With auxin production halted for a short time, growth is spread throughout the entire plant instead of the strongest growth only happening at the top of the plant.
Another benefit of deadheading is that removing wilting plant matter reduces disease potential in your garden as well as possible food sources for pests. Bacteria, viruses, molds, fungus and other pathogens are most adept at utilizing dying or dead plant matter to proliferate. Even the wilting petals of flowers can attract such undesirables as slugs, earwigs, weevils and aphids too. Once a cycle of pests gets a foothold, they can perpetuate their own reign of doom for plants, spreading disease, which causes more plant dieback, more food for pests, and more offspring of pests surviving due to the favorable conditions. “Nip it in the bud” and you will prevent the majority of such woes before your afflicted with them.
Though there are other benefits to deadheading, a final one I’ll deal with is the fact that deadheading gets you out in the garden, working close to your plants. This is perhaps the best way to monitor overall plant health, pest populations and affords you an ideal time to reap the “therapeutic” aspect of gardening. You’ll see if the lilies are starting to suffer from the heat and drought, so you can change the sprinkler setting to water them a little more. You’ll notice if the aphids are attacking the roses in great numbers and be able to enact controls that keep them from overpopulating. You might see new root-suckers growing up where you took out a burning bush last season, or even find a new lavender seedling to move into a desired location. A garden can be full of delights and wonders that you’ll miss if you don’t MAKE the time to be in your garden.
I encourage deadheading for all the above reasons and others that you find for yourself. It’s good for the plants, good for anyone that sees your garden, good for you, good for the compost pile and therefore good nearly all the way around.