When I plant annuals, perennials, hydrangeas or roses, I expect them to provide flower power in our garden from summer into fall. It’s easy to do by simply deadheading—removing old or spent (finished) flowers. For many of my plants, deadheading encourages more blooms, especially on annuals, such as salvias and zinnias, perennial coneflowers and repeat blooming roses.

There are other reasons to deadhead flowers. I’m not really a neat freak in the garden, but removing spent blooms cleans up the plant and makes it look tidy. For example, peonies and daylilies often have soggy looking, limp blossoms once they’ve finished blooming. I simply cut them off and into the compost pile they go. Off come the spent stems of hosta and coleus flowers. I’d rather look at the spectacular variations of the foliage than the spent flowers. Ditto for pinks (Dianthus chinensis). I want the attention focused on the plant’s beautiful silvery foliage rather than the dried, brown seed heads. You get the picture. It’s all about the show.

Deadheading Shrubs

I grow several varieties of butterfly bush (Buddleia) for their fragrant, pollinator-attracting blossoms. But the dried brown seed heads detract from the colorful flowers, especially on white-flowered specimens. As soon as the flowers turn brown, I clip them off along with several inches of the stem. This not only encourages more blooms but allows the stem to send out two side shoots with more buds, making for a more substantial plant. As we move into late summer, the clusters of flowers are smaller but more numerous.

Annabelle hydrangeas bloom on new wood and as I cut the huge blossoms for use indoors the plants continue to send up flowering stems. Depending on the length of our growing season, the same thing happens when I remove flowers on our panicle hydrangeas—Lime Light, Little Lime, Quickfire and Vanilla Strawberry. More flowers appear. However, as the panicle hydrangea flowers change color, I leave them intact where they create quite a show going into autumn.

Stop the Takeover

Deadheading also prevents self-sowing, especially with plants that can be aggressive. Brazilian vervain (Verbena bonariensis) is an annual that loves to self-sow everywhere in our garden (except in places where I really want it to grow). This plant is a great pollinator magnet, attracting butterflies galore while in bloom. But once the flowers turn brown and dry, I clip off the seed heads and store them in a paper bag until I’m ready to plant them where I want them next spring.

Other aggressive self-sowers include goldenrod, garden phlox, Joe Pye weed, clustered bellflower (Campanula glomerata) and boneset (Eupatorium)—perennials that spread by roots and seeds. Deadheading helps me control these rambunctious plants.

Bloom & Bloom Again

I use all-purpose fertilizer granules when planting in spring—especially in my 50-plus containers. Later in the summer, I’ll use a water-soluble fertilizer—one that says 10-54-10 on the label—once every two weeks. That high middle number encourages flower formation and root development.

Fertilizing is especially important if you want big, beefy annuals, like zinnias, my favorite plant. I grow many of the taller varieties as well as the small compact Profusion and Zahara series. We enjoy the tall zinnias as cut flowers and as nectar sources for butterflies.

As soon as the flowers start to fade, I clip them off. That will give me crayon-colored zinnia flowers up until mid-October when we typically have the first fall frost. But don’t remove all of the flowers. Some seed heads will be left on the plants to dry before I pick them off and store them for use the following spring.

Another favorite daisy-like flower is Rudbeckia hirta (an annual black-eyed Susan available in yellow, gold, burgundy and bi-colored flowers). This plant also benefits from deadheading and will continue to produce flowers especially when fertilized. This works for Shasta daisy (Leucanthemum × superbum, a perennial, as well.

Many of the annual salvias continue to bloom until frost. They are an important source of nectar for migrating hummingbirds and monarch butterflies that explore our garden in autumn. As soon as I see the blue flowers fading on Indigo Spires or Mystic Spires salvia, I cut the flowering stem down to the bottom or to a stem with a flower bud below.

Occasionally, the perennial tickseed (Coreopsis) and wild geranium (Geranium maculatum) will have a big flush of bloom in early summer and then go to seed. That’s when I use hedge clippers to cut the entire plant back by half its size. This encourages new foliage and sporadic rebloom.

Coneflowers (both Rudbeckia fulgida and Echinacea purpurea) also benefit from deadheading. But, I stop removing spent flowers in late August—I want the seed heads standing for winter interest and as a source of food for winter-visiting birds such as goldfinches and chickadees.

Tradescantia (spiderwort) is a favorite perennial in our moist shade garden. After the first big flush of flowers in May, deadheading helps encourage the plant to bloom sporadically the entire summer. Rather than remove each spent flower, I cut the entire plant down to about six inches, removing leaves and flower stems. And then I just sit back and wait. (Not really. Do any gardeners spend time relaxing in a chair just looking around? We should.)

Don’t Deadhead These Wonders

I don’t deadhead plants that I want to spread, such as our native woodland phlox (Phlox divaricata) and Shasta daisies, which are usually short-lived in our garden. I want them to go to seed and self-sow around the garden. If they show up where they’re not wanted, I move them to another location or pot them up for gardening friends.

Some perennials will not rebloom even if you remove the spent flowers. They are genetically predisposed to bloom just once. These one-time bloomers include astilbe (Astilbex arendsii), Siberian iris (Iris siberica), peonies, perennial poppies, gayfeather (Liatris) and bigleaf ligularia (Ligularia dentata). Add to that list bluestar (Amsonia), old-fashioned bleeding heart, Baptisia and Oriental poppies (Papaver). Enjoy them while they’re in bloom and surround them with other, longer-blooming perennials and annuals to create a season-long succession of color.

That urge to tidy up slows down in late August. I leave certain dried flower heads intact for fall and winter interest. There’s nothing that I enjoy more on a cold winter day than looking at the dark seed pods of baptisia, as well as the seed heads of liatris, astilbe, coneflowers, globe thistle, eryngium, butterfly bush and ornamental grasses, dusted with snow. It brings back pleasant summer memories.

Spent flowers on hybrid tea, floribunda, and grandiflora roses should be removed regularly to encourage a second flush of bloom. However, I stop deadheading just before Labor Day to avoid encouraging new growth that can be damaged by early cold temperatures. I also want the plants to produce attractive red and gold hips (fruits of roses that contain seeds). Many roses—especially old garden roses—produce large hips, which provide good winter interest.

Shrub roses such as the ‘Knock Out’ series are “self-cleaning”—they drop their spent flowers—and will rebloom continually throughout the growing season with no deadheading necessary. If pruning is needed on climbers or ramblers that only bloom once, it should be done immediately after flowering, because blooms are produced on old wood.

Good Reads

The Well-Tended Perennial Garden: The Essential Guide to Planting and Pruning Techniques, Third Edition, Tracy DiSabato-Aust, Timber Press, 2017.

Growing Flowers: Everything You Need to Know About Planting, Tending, Harvesting and Arranging Beautiful Blooms. Niki Irving, Mango Publishing, 2021.