18 Flowers to Deadhead in August for One More Big Burst of Blooms

By August, even a beautiful flower bed can look as though it has suddenly given up. Fresh petals have been replaced by brown buttons, dry stalks, and half-empty flower clusters.

Many of those plants are not actually finished. They are simply putting their energy into seeds instead of new buds. Removing the spent flowers at the right point can encourage fresh branches and another round of color before frost.

The location of the cut matters. Snipping off only the petals may leave the seed-producing portion behind, while cutting too far down can remove the very buds you are trying to encourage. It is also worth leaving a few late seed heads for birds, natural reseeding, or next year’s seed collection.

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1. Zinnias

Pink zinnia flower viewed from above among green foliage

Zinnias are some of the best flowers to deadhead in August because they can respond surprisingly fast. A patch that looks tired and brown may begin producing fresh side branches once its old flowers are removed.

Where to cut: Follow the flower’s stem down until you reach the first strong pair of leaves or a leafy side branch. Make the cut about ¼ inch above that junction. Cutting only beneath the flower head leaves an awkward bare stem and usually produces a weaker-looking plant.

Red double zinnia flower blooming in a garden

The deeper cut also produces longer new stems, which is useful if you like bringing zinnias indoors. Continue removing faded flowers throughout August, especially before their centers become dry and crumbly.

Leave for seeds? Yes, but wait until later in the season. Leave several flowers on your healthiest plants and allow the heads to become completely brown and dry. Keep in mind that seeds collected from hybrid zinnias may produce different colors or flower shapes next year.

2. Marigolds

Several large orange and yellow marigold flowers growing in a container

Marigolds can bloom until frost, but they may slow down dramatically once dozens of old flowers begin developing seeds. The common mistake is pulling away the dry petals while leaving the thick green base attached.

Where to cut: Remove the faded petals, the swollen flower base, and the short piece of stem beneath it. Pinch or cut the stem immediately above the first healthy set of leaves or small side shoot.

Two ruffled orange marigold flowers in close view

That swollen base is where the seeds develop. As long as it remains on the plant, the marigold may continue investing energy in it even though the colorful petals are gone.

Leave for seeds? Leave several late flower heads on your strongest plants. Wait until they are dry, brown, and papery before opening them. Inside, you should find narrow black-and-cream seeds that are easy to store.

3. Cosmos

White cosmos flower with an insect resting on its yellow center

Cosmos often become tall, airy, and a little unruly by August. They can still put on a strong fall show, but old seed heads must be removed before the plant decides its job is finished.

Where to cut: Trace the thin flower stem down to the nearest leafy side branch. Cut just above the branch instead of leaving a long, bare stem. New growth can then take over from that junction.

Magenta cosmos flower with unopened buds and feathery green foliage

If the whole plant has become tall and thin, shorten several of the longest stems by roughly one-third. Always cut above a leafy node and avoid stripping away most of the green foliage during very hot weather.

Leave for seeds? Cosmos are excellent seed producers. Deadhead the early flowers, then allow a few of the healthiest late blooms to form long, pointed brown seeds. They are easy to collect, and those left behind may scatter themselves around the garden.

4. Petunias

Deep purple petunia flower surrounded by green leaves

Petunias can look spectacular in June and completely exhausted by August. A container may be covered with long stems, sticky foliage, and faded flowers hanging from the ends.

Where to cut: Pinch off the wilted flower, its short stem, and the small swollen seed capsule directly beneath the petals. Removing only the limp trumpet does not fully deadhead the plant.

Pink and white striped petunia flower in close view

For a leggy petunia, ordinary deadheading may not be enough. Cut the longest stems back by one-third to one-half, making each cut just above a leafy node. The plant may look sparse for a week or two, but the remaining nodes can produce several new branches.

Leave for seeds? Usually not. Many popular petunias are hybrids, so seedlings may not resemble the parent plant. Some newer varieties are also sold as self-cleaning petunias and naturally drop their faded blooms, although they can still benefit from an August trim when they become stringy.

5. Dahlias

Pink dahlia flower covered with small water droplets

A healthy dahlia can continue flowering until frost, but each fading bloom begins taking energy away from the buds waiting below it. The hardest part is sometimes telling an old flower from a new bud.

A developing dahlia bud is generally firm and rounded. A spent flower head becomes pointed, soft, papery, or slightly hollow. Check carefully before cutting so you do not remove tomorrow’s flower.

Magenta dahlia flower blooming among stems and unopened buds

Where to cut: Follow the finished flower stem down to the first strong pair of leaves or branching point. Cut immediately above that junction. Do not leave an empty flower stalk standing above the foliage.

Leave for seeds? Deadhead them all when flowers are the main goal. Dahlias grown from collected seed can be fun, but they rarely reproduce the exact color and form of a named parent. Gardeners normally save a favorite variety by storing its tubers.

6. Geraniums

Red pelargonium flower cluster commonly sold as a container geranium

The familiar “geraniums” sold for porches and containers are usually pelargoniums. Each rounded cluster contains many flowers, and the entire cluster eventually collapses on one long stalk.

Where to cut: Follow that long flower stalk all the way down to the point where it joins the main stem. Cut it cleanly at the junction, or gently snap it downward if it releases easily. Do not leave several inches of empty stalk behind.

Bright magenta pelargonium flower cluster above rounded green leaves

Removing the complete stalk opens the plant, improves its appearance, and directs growth toward younger flower stems. Yellow leaves can be removed at the same time, but avoid stripping away healthy foliage.

Leave for seeds? Most container geraniums can be deadheaded completely. Gardeners who want an identical plant usually take cuttings rather than collecting seed, since hybrid seedlings can vary considerably.

7. Snapdragons

Pink snapdragon flowers arranged along a green stem

Snapdragons often produce one impressive central spike followed by shorter side shoots. Once the central spike turns brown, those smaller shoots may be the plant’s best chance for another display.

Where to cut: When most flowers on the spike have faded, follow it down to the highest strong pair of leaves or visible side shoots. Cut the old spike just above those shoots.

Bright pink snapdragon flowers with unopened buds at the top of the stalk

Look closely before using the shears. The small green growth emerging from the leaf joints is exactly what you want to preserve. Cutting through it removes the stems that could carry the fall flowers.

Leave for seeds? Save one or two of the final spikes if you want seed. Otherwise, remove the round developing pods. Snapdragons can produce a surprising amount of seed once flowering is allowed to finish.

8. Verbena

White garden verbena flower clusters rising on green stems

Verbena can develop a layer of faded flower clusters over otherwise healthy foliage. Removing those brown clusters helps expose the fresh growth underneath and prevents the plant from looking finished too early.

Where to cut: Follow each finished cluster down to the next full pair of leaves. Cut directly above that leaf pair rather than removing only the tiny individual flowers.

Close view of a rounded purple verbena flower cluster

When nearly every cluster has faded at once, lightly shear the plant back by about one-quarter. Keep plenty of green foliage on the plant, particularly during a stretch of intense August heat.

Leave for seeds? Leave a few late clusters only if you want natural reseeding. Seedlings from hybrid verbena may not match the original plant, and some varieties produce little useful seed.

9. Salvia

Upright woodland sage flower spike with small blue flowers

Perennial salvia frequently forms a second, smaller round of flowers after its first spikes are removed. By August, the brown spikes may be hiding short green shoots that are already forming below them.

Where to cut: Trace each faded spike down to the first pair of healthy leaves or side shoots. Make the cut immediately above that point.

Purple woodland sage flower spike with violet flowers and reddish bracts

If nearly every spike has finished together, the top third of the plant can be trimmed evenly. Keep the lower leafy mound intact. Fresh flowering stems often emerge from the nodes beneath the cuts.

Leave for seeds? Remove the early spikes when another bloom is the priority. Leave some of the final spikes if you want seeds, natural seedlings, or additional late-season structure in the garden.

10. Coreopsis

Yellow threadleaf coreopsis flower surrounded by narrow green foliage

A mature coreopsis may carry hundreds of small brown heads by August. Deadheading every stem individually works, but it can turn a simple garden job into an all-day project.

Where to cut: For scattered faded flowers, follow each stem down to the next leaf or side bud and cut immediately above it. When the first major flush is completely finished, shear the flowering portion of the plant back by roughly one-third.

Several yellow lanceleaf coreopsis flowers blooming above green leaves

Do not cut into the crown or remove the entire mound of green basal foliage. The plant needs those leaves to recover and build the smaller buds that may carry its late-season flowers.

Leave for seeds? Deadhead the first flush, then allow some of the final heads to mature. The dry seed heads can feed small birds and may produce volunteer plants nearby.

11. Blanket Flowers

Yellow blanket flower blooming above green foliage

Blanket flowers can bloom for an impressively long time, but the round seed heads form quickly. Once those heads cover the plant, new flower production often slows and the entire clump begins to look dry.

Where to cut: Trace each bare flower stalk down to the first healthy leaf, unopened bud, or side branch. Cut just above that living growth.

Red and yellow blanket flower with a rounded central disk

When there are too many old heads to remove individually, lightly shear the plant back by about one-third. Leave a healthy green framework underneath and water the plant after trimming if the soil is dry.

Leave for seeds? Yes. Remove the earlier heads for more flowers, then allow several of the final round heads to remain. They can provide seeds for birds and give you material to collect for future planting.

12. Bee Balm

Red bee balm flower blooming against broad green leaves

Bee balm often hides smaller flower buds beneath its large central bloom. Cutting in the wrong place can remove those buds, while a careful cut can give them room to open.

Where to cut: Remove the faded central head by cutting immediately above the next pair of leaves or visible side buds. When the entire stem has finished, follow it lower and cut above a strong leafy side branch.

Pink bee balm flower surrounded by green leaves

Do not automatically cut every flowered stem to the ground in August. Healthy lower leaves are still feeding the plant, and some stems may contain buds that are difficult to see from above.

Leave for seeds? Deadhead the first round, but consider leaving some of the final heads. Their dark shapes provide winter texture, hold seeds for birds, and may produce a few new plants.

13. Garden Phlox

Large clusters of pink garden phlox flowers

The large central cluster on garden phlox usually opens first. Smaller green buds may be tucked immediately beneath it, ready to extend the show if the old cluster is removed carefully.

Where to cut: Remove the entire faded flower cluster just above the first full pair of leaves or developing side buds beneath it. Do not cut through those small buds or leave a long bare stump.

Purple-pink garden phlox flower cluster growing among green leaves

The side clusters are often smaller than the original display, but they can keep color on the plant for several more weeks. Removing faded clusters also gives a crowded phlox planting a cleaner appearance.

Leave for seeds? Most gardeners can deadhead garden phlox completely. Leave several final clusters only when volunteer seedlings are welcome. Named cultivars may produce seedlings that differ from the parent plant.

14. Shasta Daisies

Many white Shasta daisies with yellow centers growing in a garden

A brown Shasta daisy left on top of a long empty stem can make the whole clump look neglected. Fortunately, there is often another bud or leafy branch farther down that can take its place.

Where to cut: Follow the spent stem down to the next unopened bud, leafy side branch, or healthy leaf. Cut immediately above that point.

Single white Shasta daisy with a yellow center against a dark background

If the stem has no additional buds or leafy branches, remove it close to the basal foliage. This is better than leaving a collection of bare sticks rising above the healthy mound.

Leave for seeds? Deadhead most flowers when continued bloom is the goal. A few of the final heads can remain for seed, although seedlings from cultivated Shasta daisies may not look exactly like the parent.

15. Catmint

Purple Little Titch catmint flowers among soft green leaves

Catmint frequently produces one heavy early flush and then relaxes into a sprawling mound with scattered flowers. A midsummer haircut can expose fresh foliage and encourage a neater second bloom.

Where to cut: Shorten the flowering stems by roughly one-third to one-half. Make the cuts just above fresh leafy growth near the lower portion of the plant.

Purple dwarf catmint flowers rising above textured green leaves

Avoid cutting below every green leaf, especially during hot and dry weather. The remaining foliage helps the plant recover. Water deeply after shearing if the soil has become dry.

Leave for seeds? Many widely planted catmint cultivars are sterile or produce little useful seed, so they can be trimmed completely. Species catmint may self-sow, so leave a few late stems only when extra seedlings are welcome.

16. Yarrow

Close view of a white yarrow flower cluster

Yarrow clusters can remain upright long after their color is gone. From across the yard they may still look like flowers, but up close the centers are dry and the supporting stem is often bare.

Where to cut: Follow the complete flower stem down to a low leafy branch or the basal rosette. Cut just above healthy foliage. Removing only the flat flower cluster leaves a long naked stalk behind.

White yarrow flower cluster viewed from above

New flowers are not guaranteed after an August cut, especially in a dry garden, but removing finished stems can expose fresh foliage and encourage smaller side growth.

Leave for seeds? Leave several well-shaped late clusters for seed, dried arrangements, or winter texture. Remove the earlier brown clusters when one more flush of flowers is the priority.

17. Coneflowers

Butterfly resting on a purple coneflower above a second fading bloom

Coneflowers present a real tradeoff. Removing the first fading blooms may encourage smaller flowers farther down the stem, but the mature cones later become valuable seed heads.

Where to cut: Follow the fading flower down to the next side bud, leafy branch, or strong leaf junction. Cut about ¼ inch above that point.

Extreme close view of the orange-red cone and pink petals of a purple coneflower

That cut preserves the smaller buds below the original flower. Cutting the entire stalk to the ground would remove those buds along with the faded head.

Leave for seeds? Definitely leave some. Deadhead the first flowers, then stop removing every head later in August. The dark cones can provide food for goldfinches and other seed-eating birds, while a few seeds may develop into new plants.

18. Black-Eyed Susans

Yellow black-eyed Susan flowers with an insect resting on the dark center of the nearest bloom

Black-eyed Susans can produce flowers over a long stretch, but the earliest blooms may already be black seed heads while newer buds are still opening. Selective deadheading lets you keep both.

Where to cut: Trace the faded flower stem to the next side bud, leafy branch, or healthy leaf node. Cut immediately above that point.

Large garden planting filled with blooming yellow black-eyed Susans

If a stem has completely finished and contains no additional buds, remove it near the leafy base. This keeps the planting tidy without cutting down stems that are still working.

Leave for seeds? Deadhead some of the earliest flowers, but leave a generous number of late heads. The seeds can feed birds, and the plants may reseed themselves in open patches of soil.

After a major August cutback, give the plants a deep drink rather than a quick surface sprinkle. Avoid pushing them with a heavy dose of fertilizer, which may produce soft leaves instead of flowers. Diseased stems and spotted foliage should go into the trash rather than the compost pile.

A practical compromise is to deadhead the plants at the front and center of the bed while allowing less-visible seed heads toward the back to mature. The garden gets one more polished burst of color without taking every last seed away from birds or next year’s seedlings.