Off With Their Heads: How and Why to Deadhead Flowers

How and Why to Deadhead Flowers - Longfield Gardens

If you are a flower gardener, deadheading is a task you can’t ignore. Removing spent flowers keeps your plants looking neat and tidy. More importantly, deadheading discourages plants from producing seeds, which helps them conserve energy so they will continue flowering.

It’s not difficult to identify which flowers are dead and need to go. But it’s good to be aware of different techniques for removing these spent flowers. Not all plants respond to deadheading in the same way.

How and Why to Deadhead Flowers - Longfield Gardens

Nigella (love-in-a-mist) is a short-lived annual. Succession sow for continuous flowering.

Deadheading Annuals

An annual is a plant that lives for only one growing season. It goes from seed to plant to flower, and then produces a crop of new seeds for the following year. Once these seeds begin to form, the plant’s mission is complete. Growth slows, new bud formation stops, and the plant eventually dies back. Deadheading delays this natural process. Removing the plant’s flowers before they can set seed, encourages the plant to continue generating new buds and blooms.

But not all flowering annuals behave exactly alike. Some are naturally longer-lived than others. Deadheading has little to no effect on short-lived annuals such as poppies, nigella, cerinthe, bupleurum, and larkspur. To extend their bloom time, sow several batches of seeds, 2 or 3 weeks apart.

How and Why to Deadhead Flowers - Longfield Gardens

A much larger number of annuals, including marigolds, zinnias, calendula and snapdragons, are inclined to continue blooming until frost if they get adequate water and nutrients. Keeping these plants deadheaded will give you more flowers and help the plants stay vigorous and attractive.

How and Why to Deadhead Flowers - Longfield Gardens

This Silverberry Supertunia is unable to produce seeds. Its spent blooms fall off on their own and are replaced by new flowers.

Thanks to plant breeders such as Proven Winners, gardeners can now plant annuals that don’t need to be deadheaded. These plants were bred to be sterile and can only be propagated via cuttings. Since the plants are unable to produce seeds, they never slow down and continue to bloom right until frost.

Though these sterile plants do not require deadheading, many of them still benefit from being cut back midseason to encourage fresh growth and improve their overall appearance. Gardeners can now purchase sterile cultivars of impatiens, petunias, calibrachoa, lantana, angelonia, verbena, nemesia, lobelia, begonias and more.

How and Why to Deadhead Flowers - Longfield Gardens

Removing spent blooms lets the remaining flowers shine.

Deadheading Perennials

Deadheading perennials is a little more complicated. There are many perennials that only produce one flush of flowers per season. Removing spent blooms improves the plant’s appearance and helps conserve energy, but it will not result in more flowers. Examples of once-blooming perennials include peonies, lilies, astilbe, baptisia, aruncus, crocosmia, Siberian iris, Oriental poppies, and most heirloom roses.

Other perennials can be encouraged to rebloom, especially if they are deadheaded. You can expect fewer flowers the second time around, and sometimes you won’t get any at all. But removing the spent flowers still benefits plants by helping them conserve energy. Perennials that may rebloom after deadheading include daylilies, salvias, delphinium, helenium, echinacea, Shasta daisies, garden phlox, reblooming bearded iris, campanula, rudbeckia, yarrow, and salvias.

How and Why to Deadhead Flowers - Longfield Gardens

This zinnia has passed its prime. Removing both the flower and the stem encourages new growth and keeps the plant healthier.

Techniques for Deadheading

As a rule, it’s good to remove spent flowers as soon as possible. Visit your plants weekly and bring along a pair of scissors to remove blossoms that have gone by. While you’re at it, remove any neighboring flowers that are no longer in their prime. Cutting flowers to bring indoors counts as deadheading!

How and Why to Deadhead Flowers - Longfield Gardens

Snap off spent daylily flowers at the base of the bloom. This will keep your plants looking more attractive. Be gentle to avoid breaking off neighboring buds.

Nipping Buds

For some plants, you can simply use your fingers to pinch or snap off spent flowers. Use this technique for annuals such as petunias, calendula, angelonia, bidens, sanvitalia, begonias, geraniums, coleus and cosmos. Perennials to nip include daylilies, clematis, campanula, lilies, and roses. Cut off the entire stalk or stem once all flowers are spent.

How and Why to Deadhead Flowers - Longfield Gardens

Cut stems of matricaria, also known as feverfew, to the ground after the flowers fade. New stems, with new flowers, will appear within a few weeks.

Removing Stems and Stalks

For other plants, it’s best to remove the stem as well as the flower. Use scissors or garden snips to make clean cuts. This technique is good for most annual cut flowers including zinnias, dahlias, asters, ageretum and snapdragons. It’s also a good way to rejuvenate petunias, coleus, calibrachoa and other annuals that tend to get leggy by midseason.

Perennial plants that should have both flowers and all or part of the stem removed include delphiniums, peonies, yarrow, foxgloves, matricaria, Shasta daisies, reblooming iris, salvias, sweet William, hostas and columbine.

How and Why to Deadhead Flowers - Longfield Gardens

Dianthus is a good candidate for shearing. Cut off the spent flowers and enjoy the lush, mounding foliage right until frost.

Shearing

Some perennials should get a haircut right after they flower. This encourages a new flush of foliage that dramatically improves the plant’s appearance. You can use snips or hedge shears, taking care to leave the newly developing foliage intact. Perennials that respond well to shearing include coreopsis, hardy geranium, perennial alyssum, silver mound artemisia, lavender, creeping phlox, candytuft, and nepeta. Shear on a cloudy day and follow it up with a dose of water-soluble fertilizer and a generous drink of water.

How and Why to Deadhead Flowers - Longfield Gardens

Learn as You Go

Don’t stress out about deadheading. No one is able to remove every spent flower in their garden. This task is about experimenting and learning as you go. Over time you’ll discover which plants benefit from it the most. This will help you determine where to focus your energy. If you grow lots of perennials, you’ll find a wealth of plant-specific deadheading recommendations in this book by Tracy DiSabata-Aust: The Well-Tended Perennial Garden.

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Starting Flowers From Seeds, Bulbs or Plants