Remove spent blossoms for more flowers

Last Updated: 
September 2, 2010
marigolds

Deadhead repeat bloomers such as marigolds. Photo courtesy of All American Selections.

CORVALLIS, Ore. – Here's a gardening "chore" that many people find pleasant. If you wander through your garden and remove spent flowers, you can enjoy your summer's successes and prolong them at the same time.

"The botanical purpose of flowers is to produce seeds so that the plant can propagate," said Linda McMahan, horticulturist with the Oregon State University Extension Service. Plants in nature do just fine without being "deadheaded," and removing spent blossoms is rarely important for the health of the plant.

"However, when you remove flowers before they start producing seeds, the chemical message to the plant is: produce more flowers."

Deadheading makes sense for repeat bloomers such as roses and highly modified annuals, such as marigolds, to keep them blooming. For most other plants, it is a matter of appearance and the personal taste of the gardener.

No special techniques or tools are required. Simply cut or pinch off fading blooms, being sure to remove seedpods that might have started forming behind the flower. Remove more than just the petals.

One of the aims of removing old blossoms is to keep plants looking attractive. For moderately bushy plants, such as marigolds, remove each fading flower and its individual stem. Bushy plants that bloom profusely at the ends of the foliage, like coreopsis, can be sheared back with grass shears. Sometimes shearing will encourage a new flush of blooming.

For plants that produce one flower at the end of a long stem, such as black-eyed Susans, cut the whole stem off at the base to avoid empty-looking stems.

Some flowers, especially annuals, can be kept blooming through the whole growing season simply by regular deadheading. Marigolds, cosmos and geraniums are examples of plants that bloom continually if flowers are consistently cut or pinched off as they pass their peak. Others, such as roses, won't bloom all summer, but they'll bloom longer if deadheaded regularly.

Some perennials may be deadheaded to keep them looking tidy, but it won't necessarily make them produce more flowers. The foliage of peony, Siberian iris, and lamb's ear will stay attractive through the season, but the plants won't bloom again after deadheading.

Gardeners who want to avoid "volunteers" or offspring seedlings starting in their flowerbeds, might want to do exhaustive deadheading. On the other hand, McMahan said, it can be a great pleasure to watch self-seeders like columbine or Shirley poppies come up in delightfully unexpected places.

"Cosmos and viola pop up readily the following spring with no effort on a gardener's part, if they're allowed to set seed," McMahan said. "Sometimes the seedlings produce interesting flowers, having worked with the birds and bees to do a little genetic mixing."

Before removing every spent flower in sight, be sure you know which plants produce attractive seeds or seed pods that you'll miss if you deadhead everything at the end of the summer. For instance, Gladwin iris has scarlet-orange seedpods in the fall, and some peonies also produce attractive seeds and seedpods.

"And of course, the more plants you allow to form seeds, the more likely seed-eating birds will visit your garden regularly."

Author: Judy Scott
Source: Linda McMahan