"As with any profession, there are terms known and understood only by the professionals," said Martha Smith. "Auto mechanics and computer technicians seem to speak their own language. But I didn't realize it was true for gardeners until a friend pointed it out to me when I nonchalantly said her flowers should be deadheaded."
"Deadheading is removing old flowers," she said. "It also can involve removing foliage to improve the appearance of the plant."
Smith described why deadheading helps.
"Consider the lovely tall bearded iris," she said. "This perennial can have two to four blooms along its stem in May. As they finish flowering, they go from stunning to mush-on-a-stem. Handpick each flower as it finishes to improve the appearance and, once all have bloomed, cut the stem back to the basal foliage."
The popular daylily (Hemerocallis species) is another plant that looks better deadheaded. Daylilies can have four to eight buds in a cluster at the end of a flower scape (another word that many may not be familiar with, which means flower stalk).
"As the name suggests each flower blooms for a day," she said. "It would be nice if the old flowers simply dropped off but no, we need to deadhead and individually remove the old flowers.
"Once they have all bloomed out, you cut out the flower scape."
Annuals need to be deadheaded, too. Remove old geranium, marigold and gazania flowers and you will again have a full-blooming plant.
There are other plants that bloom in a flurry with many flowers covering the plant. Threadleaf coreopsis is an example. Sunny yellow flowers cover the plant for three to five weeks starting in June. Once they are bloomed out, simply take your shears and lop off the flowers plus about 3 to 5 inches of growth, depending on cultivar.
"This may seem bold, but the plant will respond with a flush of new crisp foliage and usually a second flush of flowering — though not as prolific as the first flush," Smith said.
Other plants such as Speedwell (Veronica sp.), perennial Salvia or Spiderwort (Tradescantia sp.) often look haggard after they bloom as the heat of summer kicks in. "Silver Mound" Artemesia often breaks open and looks sad. Deadhead these plants after they bloom, but also remove most of the foliage. Cutting back to basal growth or 4 to 5 inches may leave an open spot in your garden temporarily, but these plants will respond and reward you with compact clean growth.
"Another advantage to removing old flowers and foliage is preventing seed production," she said. "Not only does this take energy from overall plant growth, but with some plants this can be a source of re-seeding.
"Purple coneflower (Echinacea sp.) is known to re-seed. Deadhead and you eliminate this issue. But, if you want to attract birds to your garden, let the flowers remain and don't complain when you have little coneflowers throughout the garden."