Deadheading – How and Why

Q: I’ve heard other gardeners talk about ‘deadheading flowers’ — exactly what is that. How do I do it?

A: Deadheading is the removal of fading flowers to encourage new blooms and keep a plant tidy. Flowering is how plants make their seeds. In order to extend the life of our flowering plants, we need to deadhead spent blooms. By deadheading, you make the plant redirect its energy into growing flowers.

Basically deadheading serves two purposes: it keeps plants looking attractive, and it stops seed production. With most flowers, it’s fairly easy to tell when to deadhead — the flower begins to fade and petals are shrivelling and drying out. If the bloom has begun to lose its color, the plant will benefit from deadheading. The longer you leave fading flowers, the longer the plant will waste energy on dying blooms.

Deadheading is done in one of two ways: by cutting off fading blooms, or by pinching them off. For flowers that will rebloom, like Coreopsis grandiflora, cut off blooms with either your fingers or a set of snips, snapping off the stem above the next set of leaves. Use shears to cut smaller, more delicate flowers.

If the blooms are on a stalk that will not rebloom when deadheaded (such as on the Rocky Mountain penstemon or buckwheats), go ahead and cut the stalk as close to the ground as possible.

Which flowers to deadhead:

• Annuals: Regular clean-up of old flowers will prolong blooms on these annuals — petunias, bachelor’s buttons, calendulas, cosmos, geraniums, marigolds, snapdragons and zinnias. Note: there are some ‘modern’ annuals that are self-cleaning. Impatiens are extremely popular in part because their finished blooms fall off to let new flowers come. The Wave series of petunias produce masses of flowers with minimal deadheading.
• Perennials: Lady’s mantle, perennial candytuft, creeping phlox (subulata), catmint, lavender and hardy geraniums (cranesbills) should be cut back by half to promote fresh leaf growth. On hostas once the flowers have bloomed the entire stem can be cut back to the ground.
• Roses: For repeat-blooming hybrid teas, floribundas and miniature roses, prune the flower stems back to the first leaf bud below the spent cluster.

Usually deadheading can be a weekly task. There are a few exceptions – daylilies and bearded iris, for example. Remove individual spent buds daily; then, once the plant has totally finished flowering, cut the stalk to the ground to keep the plant looking good.

When NOT to deadhead:
At the end of summer, allow dying blooms to remain on the plant. In order to encourage some perennials to propagate themselves, leave some blooms to dry out and go to seed. Lupine, hollyhocks, foxglove, and morning glory are good examples of plants that will self-sow. The flower will produce seeds which you can collect, or if you have a casual cottage style garden, allow the flowers to reseed themselves in your garden. Another reason to leave these late finished blooms on the plants is to provide food for wildlife. The seedheads of purple coneflower and perennial sunflowers are just a few of the flowers that become feeding stations for birds.

For more information on deadheading flowers and garden care in general, check out The Well-Tended Perennial Garden by Tracy DiSabato-Aust. The book provides good information on maintaining specific plants.

Contributed by Eileen Tully, Colorado Master Gardener. Photo courtesy of Colorado State University Extension. For answers to your horticultural questions, contact the Master Gardener Help Desk at 520-7684 or CSUmg2@elpasoco.com. Access fact sheets and seasonal information on the El Paso County Horticulture website http://elpasoco.colostate.edu/horticulture/.