Deadheading, removing spent blooms, should be done throughout the growing season. But by midseason, many of your plants probably need a good cleanup, beginning with a thorough deadheading.
Most flowering plants, annuals, perennials and some flowering shrubs, will benefit from removing the dead blooms. Some continue to produce new blooms whether you deadhead or not, but many will not continue to flower unless you deadhead. A flowering plant’s sole purpose is to reproduce. All its’ energy is focused on producing flowers, which in most cases develop into seeds. If the “dead” (they really aren’t dead, the seeds inside the flower are still developing) or “spent” blooms are removed, some plants divert their energy to plant growth, or starts over with the flowering process. If the seeds are allowed to mature, they may drop to the ground and grow more plants, or some gardeners collect them for propagation later. Some plants, like certain rose varieties, will develop brightly colored hips from the blooms. By autumn these hips add new color and interest to the garden. In the case of blooms that produce colorful fall hips or berries, you may prefer to allow them to develop rather than deadhead the last flush of blooms.
In addition to encouraging additional blooming, deadheading will refresh your garden. Dead blooms will soon blanket your garden with unappealing brown and shriveled flowers, becoming quite unsightly. And by midseason, many annuals and perennials become overgrown, gangly and just plain messy looking. A thorough midseason deadheading, and some trimming of overgrown and sun damaged foliage, will bring new life to your garden. In no time at all you will have new blooms and bright new foliage growth. When in doubt, deadhead - you cannot do more harm than good.
Before getting into which plants should be deadheaded and when, the first question to address is how? Taking a very simplified approach, look at your plant and decide “what would be the easiest way to remove the blooms”. Most often that will be, if not THE right way if there is such a thing, a perfectly adequate way. Do keep in mind that when you remove a bloom, an empty stem sticking out of the plant is not much prettier than a shriveled up bloom. So for plants that produce a bloom on a long stem, you may want to remove that stem either completely to it’s base, or at least to the level of the foliage. Deadheading methods are pretty simple, and some of your deadheading is eliminated by just cutting flowers to bring inside for a vase.
Pinching - the same way you pinch back a plant stem to a pair of leaves to encourage bushier growth. Grasp the stem between your thumb and forefinger below the flower head, and just above a set of leaves. Pinch the stem between your fingers to break off the stem. (This is a bit more efficient with a bit of fingernails, but you can “snap” the stem off with a quick bend too.) If you would also like to trim back the plant a bit, remove up to half the stem just above a set of leaves instead of just under the bloom.
Snap - plants that bear blooms on top of long stems will usually snap off easily. Follow the stem with your fingers all the way to the base and snap off with a quick downward bend. The stem does need to be strong to snap cleanly though, if you try it on a plant that just bends or tears, you will need to snip them off with a pruner to get a clean cut.
Snip - make a clean cut with hand pruner. Cut anywhere below the spent bloom: at the first set of leaves to just remove the bloom; or further down the stem just above a set of leaves or where another stem joins to trim the plant back. This usually works well when the stem is tough or woody and when you want precise, clean cuts as with roses.
Shear - plants with many delicate blooms covering the plant are easiest to deadhead with a grass shears. Removing individual blooms as they shrivel can be extremely tedious. Using a grass shears will make quick work of the job, and you can shear back the entire plant if it has become overgrown. If you wait until all blooms have died, the plant will probably have become pretty scraggly looking. But even if you shear earlier and lose some fresh blooms, many annuals and perennials will rebloom soon anyway, and your garden will look much fresher in the meantime.
Some plants produce colorful hips, berries or seeds that attract birds. Some just have interesting dried flower heads that will add to your winter garden. You may not want to deadhead these plants, wait until early spring to trim back if you prefer:
Ornamental Grasses - interesting seed heads
Allium - interesting seed pods
Clematis - many have interesting seed pods
Coneflower (Rudbeckia and Echinacea) - will, however, self seed profusely
Plants that will rebloom, or bloom more, after deadheading:
Achillea - responds well to deadheading, will self seed if not deadheaded (pinch, snip or shear)
Alyssum - will increase bloom, but will continue to bloom adequately and without looking unsightly, without deadheading (shear)
Ageratum - will increase bloom (pinch)
Bachelor’s Buttons - may self seed if not deadheaded. (pinch or shear)
Begonia, tuberous - female flowers only will rebloom (pinch)
Bleeding Heart - will encourage longer bloom (pinch or snip)
Calendula (pinch or snip)
Campanula - will rebloom (snip, pinch or shear)
Campanula, white and blue clips - will increase bloom, and may reseed, sometime profusely, without deadheading. (shear)
Canna - may only have a single blooming in cold climates. Remove only the spent flower, additional buds may be forming below it on the stalk. (snip - only when buds have ceased to form.)
Centaurea Montana - remove blooms only, buds will continue to set along stem. Remove the entire stem when all buds have bloomed and faded.
Cleome, Spider Flower - will self seed profusely without deadheading (pinch)
Coleus - pinch out flower stalks if you like, this is a personal preference.
Columbine - will self seed if not deadheaded. (snip)
Coral Bells, Huechera - will rebloom (pinch, snip or shear)
Coreopsis - will rebloom (pinch, snip or shear)
Cosmos - will respond very well to deadheading. Pinch back half to two thirds of the stems if you prefer to keep the plant compact. May self seed profusely, perhaps even with deadheading. (pinch or snip)
Daisy - will increase bloom (snap, snip or shear)
Dames Rocket - will rebloom (snip)
Daylily - will increase bloom, but don’t cut the entire stalk. New buds may be forming below spend blooms. Snip only the spent bloom. (snip)
Dianthus - will increase bloom (shear)
Dianthus barbatus, Sweet William - will self seed if not deadheaded. (snip or shear)
Fernleaf Yarrow - will rebloom. May self seed if not deadheaded (pinch or snip)
Feverfew - will rebloom (pinch or snip)
Flax - will rebloom (pinch snip or shear)
Gallardia - responds well to deadheading. May self seed profusely without deadheading. (snip or shear)
Geraniums -Annual Pelargonium (snap)
Delphinium - will rebloom (snip)
Echinacea - will self seed profusely without deadheading (snap, pinch, snip or shear)
Iris - Reblooming Iris only (snap or snip)
Lavandula/Liatrus, Lavender - (shear)
Lupine - will rebloom (snip)
Marigolds - responds very well to deadheading (pinch)
Mirabilis, Four o’Clocks - will self seed profusely unless deadheaded (pinch or shear)
Monarda - responds well to deadheading (snip or pinch)
Mums (snip, pinch or shear)
Nicotinia - will increase bloom, will reseed if not deadheaded. Deadhead periodically to keep the plant looking neat. (snip)
Nigella, Love in Mist - will self seed profusely without deadheading ( shear)
Pansy - responds very well to deadheading. Pinch back long stems midseason. (pinch)
Petunias - will continue to rebloom without deadheading, but deadheading will encourage fuller plants with MORE reblooming. Pinch back long stems periodically to keep the plants compact. (pinch, or just pull off the dried bloom)
Phlox - will rebloom. May reseed without deadheading (snip or shear)
Platycodon, Balloon Flower - remove individual flowers as spent, being careful not to remove developing buds. (snip or pinch)
Roses - NOT ALL will rebloom. (Check the Roses pages for more info) (snip)
Rudbeckia - responds very well to deadheading (snip or snap)
Salvia, perennial (pinch)
Scabiosa - responds very well to deadheading (snip or shear)
Snapdragon - may reseed if not deadheaded (shear)
Threadleaf Coreopsis (shear)
Veronica - will rebloom (snip or pinch)
Zinnia - responds very well to deadheading (snap)
Deadheading will NOT produce an additional blooming on these plants. Some of these plants only bloom once, even if deadheaded and some will rebloom WITHOUT deadheading (deadheading may, however, improve the appearance of the plant):
All Flowering Bulbs bloom only once. Remove only the flower stem after blooming, allow the foliage to die back naturally before removing.
Artemesia - will not rebloom, but deadheading will allow the plants energy to revive foliage, which often deteriorates after blooming.
Astilbe - will not rebloom, but dried seedheads are attractive
Bearded Iris - will not rebloom (snip)
Begonia, fibrous - self cleaning and continuously bloom
Calibrachoa (million bells) - continues bloom without deadheading
Hosta - will not rebloom.
Impatiens - self clean and continuously bloom
Lamb’s Ears - will not rebloom, but deadheading will allow the plants energy to revive foliage, which often deteriorates after blooming.
Lilac - will not rebloom, but must be removed immediately after blooming. Next year’s flower buds are set just after current years’ bloom.
Lobelia - self cleaning and continuously bloom. Prune back long stems midseason if you like.
Moss Rose - self cleaning
Ornamental Grasses -dried seedheads are attractive and attract birds
Peonies - will not rebloom
Periwinkle - pinch back long stems midseason to keep the plant neat.
Petunia: the Wave; Surfinia and Fantasy- self cleaning, continues bloom. Pinch back long stems periodically to keep the plants compact.
Poppies, Oriental - will not rebloom, but California Poppy will self seed profusely if not deadheaded (shear)
Rhododendron- will not rebloom. If you want to remove spent flowers, remove only the bloom, pinching off by hand carefully. New growth has begun to develop right behind it.
Verbena - self cleaning and continuously bloom
Be careful about your late summer bloomers when doing a mid season cleanup. If you cut back to control growth in July, you may forfeit August and September flowers on the late season bloomers. These should be pinched back to control size or encourage dense growth in June. Reducing a plants size by half to two-thirds early in the growing season will often result in more, but smaller blooms. If the plant typically gets so tall that it must be staked, this may be effective in eliminating the need for staking.