How to deadhead cosmos?



Genus Cosmos has about 20 species of annual and perennial plants in the Asteraceae family, the family of sunflowers, Daisies and Asters. Cosmos genus includes, Cosmos bipinnatus, commonly known as Mexican Aster and Cosmos sulphureus, Yellow Cosmos , and Cosmos atrosanguineus Chocolate Cosmos.

Kingdom Plantae Division Magnoliophyta Class Magnoliopsida Order Asterales Family Asteraceae Tribe Heliantheae Genus Cosmos

Cosmos flowers are produced in a capitulum. Cosmos flower Capitulum is surrounded by a ring of broad ray florets and a center of disc florets. There is a lot of color variation in between the species. Cosmos flowers are 2-4 inches in diameter. Cosmos flowers come in brightly colored single or double flowers which include white, pink, orange, yellow, and scarlet colors.

Facts about Cosmos flower

  • Cosmos are herbaceous perennial flowering plants.
  • Cosmos flower plants grow to 3-6 feet tall.
  • The leaves of Cosmos plant are simple, pinnate, or bipinnate, and are arranged in opposite pairs.
  • The word Cosmos is derived from the Greek, which means a balanced universe.
  • Cosmos flower blooms twice a year and only once in the season.
  • Cosmos flowers blooms heavily, but dies with first frost.
  • Cosmos flowers can regrow in the following spring if seed falls on bare ground.
  • Cosmos flowers occurs in Solid pink, white, maroon, and pink with deep pink flares.
  • Cosmos flowering plants can be grown quickly and successfully in all regions.
  • Cosmos seeds are miniature pine needles.
  • Cosmos seeds are one of the easiest seeds in the world to grow.
  • Chocolate cosmos or Cosmos atrosanguinea, fills the air with its sweet scent of vanilla tinged chocolate.
  • Lace cosmos have more rows of petals, and have ferny foliage of a very delicate texture. Cosmos sulphureus plant leaves resemble those of marigolds (member of the Compositae, to which Cosmos belongs).

from our stores – Pickupflowers – the flower expert

Growing Cosmos flowers

  • Sow the cosmos seeds directly just before the last frost.
  • Give 12 inches of space between the plants.
  • Spread the cosmos seeds over freshly turned bare soil.
  • Press the seed into the dirt, and do not cover the seed.
  • Cosmos seeds germinate quickly.
  • Cosmos plants normally grow to 4-5 feet in a season.
  • Most of the Cosmos varieties are annuals, but there are perennial varieties also.
  • Perennial varieties of cosmos are Rhizomes and can be propagated by division.

Caring Cosmos flowers

  • Spent flowers should be deadheaded regularly, as it keeps cosmos in bloom for many weeks.
  • Overfertilizing and overwatering reduces the flower production.
  • Cosmos flower plants are drought tolerant but water Cosmos plants during long dry spells.
  • After the plants die after the first frost, remove them, and keep as compost, which helps as mulch for the next year plants.

Also have a look at some other Flowers

Rose Flower Daisy Flowers Iris
Jasmine Tiger Lillies Lily Flower
Marigold Morning glory Larkspur Flower
Peony Flower Sampaguita Daffodils
Lisianthus Agapanthus Gladiolus
Carnations Tulips Summer Flowers
Exotic Flowers Tropical Flowers Spring Flowers

Cosmos Flowers

With finely cut leaves, showy flowers and a long blooming season, Cosmos are half-hardy annuals or perennials blooming profusely from early or midsummer until fall, depending on varieties. Ridiculously easy to grow, fairly pest-free and low maintenance, they attract birds, bees, and butterflies to your garden. They are grown in borders, in containers and for cutting. They make excellent cut flowers thanks to their long vase life and richly colored petals which compliment any bouquet.

Native to Mexico, most of the cosmos we grow derive from three species:

Cosmos atrosanguineus (Chocolate Cosmos)

Highly sought after, Cosmos atrosanguineus are half-hardy, tuberous perennials boasting chocolate-scented, velvety deep crimson flowers, up to 2 in. across (5 cm), from midsummer to fall. Their pinnately divided leaves are often lobed at the base and are attached to the stems by winged petioles. These profuse bloomers create a striking visual impact in the garden and look particularly outstanding when combined with ornamental grasses. They are also ideal in containers where their fragrance can be enjoyed.

Cosmos atrosanguineus

Cosmos atrosanguineus Chocamoca

Cosmos bipinnatus (Mexican Aster)

True eye-catchers, Cosmos bipinnatus are bushy, half-hardy annuals boasting single, semi-double or double daisy-like flowers, as large as 5 in. across (12 cm), in a wide array of colors including pink, white, red and bicolor varieties. Blooming for months from early summer to fall, the ravishing blossoms are borne atop branching stems and float above the fine, feathery foliage. Ranging from 2-5 ft (60-150 cm), tall varieties are ideal towards the back of mixed borders or in a row for cutting, while smaller cosmos varieties are perfect for the patio and terrace or at the front of borders.

‘Sensation Picotee’


Cosmos sulphureus (Sulphur Cosmos)

Also called Orange Cosmos or Yellow Cosmos, Cosmos sulphureus are half-hardy annuals boasting vibrant, semi-double or double flowers, up to 2 in. across (5 cm), in shades of yellow, orange or scarlet. Neat and tidy, with profuse blossoms and slightly broader, darker leaves, these cosmos generally grow up to 1-3 ft tall (30-90 cm) and perform very well in hot climates. Bringing showers of sparks in the landscape or containers, they can also be cut.

‘Cosmic Yellow’

‘Bright Lights’

‘Cosmic Red’

Growing Cosmos Flowers

  • Cosmos perform best in full sun, in average, moist, well-drained soils. They like soil that is not too rich, as rich soil will encourage foliage at the expense of bloom.
  • They are ideal additions to beds and borders, containers, cottage gardens, prairies and meadows and cutting gardens.
  • Cosmos are perfect for mixing with roses (such as summer-long hybrid musks, English roses), or with buddlejas, border phlox, penstemon, monardas, campanulas or veronicas.
  • Propagate by seeds. Seed can be sown outside after the danger of frost has passed. It takes about 7 weeks to first bloom. If you want a head start, you can plant cosmos indoors 4-6 weeks before the last spring frost.
  • Pinching off dead blossoms will promote continuous blooming. If the flower heads remain, the cosmos will self-seed, but will not become a nuisance.
  • Keep an eye out for aphids, slugs, gray moulds.

‘Sonata White’


Eight plants to grow with cosmos

Cosmos are half-hardy annuals with daisy-like flowers that are easy to grow from seed and are incredibly long flowering, from midsummer until the first frosts.


They’re very useful for filling gaps in summer borders, look good in meadow-style planting schemes and are ideal for container displays. They make fantastic cut flowers and are great for wildlife, too – they attract bees, butterflies and hoverflies.

Discover 10 colourful cosmos to grow.

For the best results, sow seeds in March or April. Harden off the seedlings before planting out in a sunny spot, and deadhead the spent blooms regularly to prolong flowering.

Cosmos look good with many different plants – here are eight inspirational combinations.

Cosmos look great in meadow-style planting schemes.

Cosmos and calendula

Here, the magenta Cosmos bipannatus ‘Dazzler’ is grown in drifts, combined with a tall marigold, Calendula officinalis ‘Indian Prince’. Both are easy to grow from seed and make excellent cut flowers.

Magenta cosmos with contrasting orange marigolds

Cosmos and zinnia

In this all-pink combination, the daisy-like flowers of pale pink cosmos are enhanced by magenta zinnias. Discover eight essential border daisies to grow.

Pale-pink cosmos complemented by magenta zinnias

Cosmos and tobacco plant

White cosmos and tobacco plant (nicotiana are two essential components of a white garden. If you mostly enjoy your garden in the evening after work, white plants work really well as they show up well in the fading light. Discover how to grow nicotiana from seed.

White tobacco plant flowers with white cosmos

Cosmos and dahlias

Cosmos and dahlias both bring colour and long-lasting blooms to gaps in borders and both are staples of the cutting patch. As their flower forms can be quite similar, grow contrasting colours. Browse our plant database for over 70 beautiful dahlias to grow.

Bright-pink cosmos with pale orange dahlias

Cosmos, thalictrum, nepeta and hardy geranium

In this blue and white display, annuals and perennials combine – the white cosmos is combined with the spray like white flowers of Thalictrum delavayi ‘Album’, the blue flowers of catnip (Nepeta racemosa ‘Walkers Low’) and Geranium ‘Orion’.

White cosmos and thalictrum with blue nepeta and hardy geranium

Cosmos, French marigold and bidens

Orange and white is quite an unusual flower combination – the yellow/orange centre of the cosmos complements the orange of the double flowers of French marigold (tagetes) and tickseed (bidens).

White cosmos with orange marigolds and tickseed

Cosmos and eryngium

Cosmos bipinnatus ‘Antiquity’ has flowers that start off crimson, then fade slightly. They contrast with the icy blue, spiky flowers of Eryngium x zabelii ‘Big Blue’.

Advertisement Pink cosmos paired with blue eryngium

Cosmos and Verbena bonariensis

Cosmos look great in meadow-style planting schemes. Here they are paired with airy Verbena bonariensis. Both plants will flower for months on end.

Mauve and white cosmos paired with purple verbena

Should You Deadhead Cosmos: Tips For Removing Cosmos Spent Flowers

Cosmos adds bright color to the summer flower bed with relatively little care, but once the flowers begin to die, the plant itself is nothing more than background filler. Plants produce flowers so that they will make seeds, and cosmos spent flowers are where the seed production happens. If the bloom is removed, the plant tries to make another flower to start the process all over again. Deadheading cosmos after the blooms start to fade will rejuvenate the plant and cause it to bloom over and over again, up until the autumn frost.

Reasons for Picking off Faded Cosmos Blossoms

Should you deadhead cosmos? The flowers are so small it seems like it may be more trouble than it’s worth, but there are ways to make the job go quicker. Instead of nipping off individual flowers with a thumbnail like you might do with a marigold or petunia, use an inexpensive pair of scissors to cut multiple blooms at the same time.

Cosmos is among the easiest of flowers to naturalize in your garden, which means when it goes to seed it will grow wildly anywhere it can reach. Picking off faded cosmos flowers before they go to seed will prevent the plant from spreading throughout the flower beds and keep your landscaping design in check.

How to Deadhead Cosmos

For flower beds with large amounts of cosmos plants, the best way in how to deadhead cosmos is by cutting back the entire group of plants at once. Wait until most of the blossoms on the plant has begun to die back, then use a pair of grass clippers or handheld hedge trimmers to shave back the entire plant.

You’ll encourage these plants to grow in bushier and thicker, while starting the entire flowering process all over again. In a couple of weeks your cosmos will be covered in a fresh batch of blooms.

Crazy for Cosmos

Of all the annual flowering plants you can grow in your cutting garden (or even the back of your veggie patch), none is more productive than cosmos. They truly are a cut-and-come-again flower: The more you harvest them, the more they bloom.

A single planting will produce buckets of airy, delicate, daisy-like blossoms for many months. You can arrange them on their own or weave them into mixed bouquets. The possibilities are endless.

Cosmos are incredibly easy to grow, making them perfect for beginning gardeners. Seeds can be started indoors to get a jump-start on the season or sown directly into garden beds once the weather warms.

Either way, cosmos will bloom in just under 3 months from the date you sow them.

To start indoors, sow seeds 4 to 5 weeks before the last spring frost, then plant seedlings into the garden once all danger of frost has passed. Be careful not to sow seed too early, because seedlings will quickly outgrow their pots before the weather has warmed enough to put them out into the garden.

Alternatively, you can sprinkle seeds in your garden once danger of frost has passed. In about a week, you’ll see seedlings sprout up from the soil. Keep the young plants protected from slugs and snails as they are getting established since new growth is quite tender.

Plants get very bushy and prefer a little extra room to spread out, so space plants 12 to 18 inches (30.5 to 46 cm) apart. Once in the ground, cosmos will grow rapidly, so be sure to stake them early, while they are still young. Cosmos also benefit from a technique called pinching, as this will encourage the already highly productive plants to branch even more vigorously.

Here’s how it’s done: When plants are young, between 8 to 12 inches (20 to 30.5 cm) tall, take sharp pruners and snip the top 3 to 4 inches (7.5 to 10 cm) off the plant, just above a set of leaves. This signals the plant to send up multiple stems from below where the cut was made, resulting in more abundant flower production as well as longer stem length.

I typically do two sowings of cosmos, a month apart. This gives me a wide range of flower types and loads of blooms for cutting from summer into fall. I list some of my favorites here.

The ‘Double Click’ series is available as a mix or in single colors. This unique double-flowered variety is loaded with fluffy blooms that look great in bouquets.

The (pictured above) includes snow white, vibrant cranberry, rosy mauve, and a lovely soft blush.

Individual colors are also available, and I am particularly fond of ‘Bicolor Rose’, ‘Cranberries’, and ‘Snow Puff’.

Nothing says country charm like pure white cosmos, and two of my favorite white varieties are ‘Purity’ and ‘Psyche White’.

‘Purity’ (pictured left) is a cheerful daisy-like bloomer that produces an abundance of pure white single, wildflower-like blooms.

The large, pure white blooms of ‘Psyche White’ (pictured right) are a mixture of single and semi-double flowers with a central ring of fluffy miniature petals. The ruffled flowers look like snowflakes dancing in the breeze.

Two recent introductions to the cosmos family remind me of the Sugarplum Fairy.

The pale blush petals of ‘Cupcake Blush’ are fused together, forming a teacup-shaped flower. Blooms are as big as the palm of your hand, and the edges look as if they have been cut with pinking shears. This romantic variety is a mix of single, semi-double, streaked, and solid flowers. Perfect for wedding work, this variety is a must-grow!

‘Cupcake White’ is a pure white version of its blush sister. Flowers are just as big and are extremely versatile for arranging.

If you’re drawn to rich, dramatic colors, look no further than these stunning beauties.

‘Rubenza’ (pictured left) is an uncommon cosmos in a vibrant range of colors. The large single blooms open with deep ruby petals and then fade into shades of muddy rose and terracotta as they age. There is nothing like this variety.

‘Velouette’ (pictured right) has fast become a new favorite on the farm and features deep mahogany flowers with delicate white striping. Tall and dramatic, this variety churns out armloads of long stems that are perfect for bouquets.

Two fun new novelty cosmos carry the most unusual colors. While both are on the shorter side, they make up for it in their exquisite coloring.

The delicate, pale yellow flowers of ‘Xanthos’ (pictured left) have green undertones. The unique ruffled flowers have a subtle inner collar and pale throat, and blossoms have a dark yellow eye encircled by tiny fringed petals with pale, serrated tips.

There is absolutely no cosmos like the beautiful ‘Apricot Lemonade’. The unique color reminds us of ‘Distant Drums’ roses—water-colored petals start out a soft apricot with a dusty lavender reverse and fade to a buttery yellow. Variations among the blooms include some flowers with a mauve ring at the throat. A bit of separation between the petals gives the impression of a pinwheel with snipped dovetail edges. A must-grow for event work.

Striking in both the garden and the vase, these fun and eye-catching varieties are a must-grow if you’re looking for something different.

The palest pink blooms with dark rosy throats make ‘Daydream’ (pictured left) an eye-catching addition to the landscape and a sweet treasure for the cutting garden or flower border. This variety has proven to be the most heat-tolerant cosmos we’ve grown.

‘Xsenia’ (pictured right) is an early-to-flower gem that is a new favorite on the farm. Shades of magenta, purple, and raspberry have an iridescent quality and age to an apricot cast. Blooms are more petite than those of other cosmos varieties, and medium-sized, healthy plants carry flowers on strong, upright stems. So many colors give the flowers a chameleon-like quality, and they mix well with a wide range of colors.

Finally, we have to mention two beautiful and hardworking pink treasures.

The delightful ‘Seashells Mix’ (pictured left) is filled with large, showy blooms that have fluted, tubular petals resembling seashells. Flowers come in a sweet pastel mix of pink, rose, white, carmine, and other unique bicolors.

‘Rosetta’ (pictured right) is a new variety that’s a must-have for arranging and looks stunning en masse. Blooms have a layer of half double petals that resemble fluffy petticoats. ‘Rosetta’ is a mix of soft pink, blush, and rose; each petal looks hand painted.

To prolong their flowering time, keep cosmos harvested regularly, and deadhead any spent flowers before they set seed. The individual blooms of cosmos don’t last a particularly long time in the vase, about 4 to 6 days, but each stem is loaded with multiple blossoms that open individually over a period of a week.

Harvest when the buds are colored but haven’t opened up yet; this will keep insects from pollinating them and help stretch the vase life by a few additional days.

For a small investment of time and garden space, you will be able to fill your house with these cheerful flowers all summer long.

I would love to hear your experience with this wonderful group of plants. Do you grow cosmos or plan to add them to your garden this coming season? If so, what are your favorite varieties?

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Bright green fernlike foliage is the perfect complement to the daisylike flowers of cosmos, which come in shades of white, pink, yellow, or orange. This cottage-garden favorite is a magnet for pollinators and easily grown from seed sown directly in the garden. Plant petite varieties, such as ‘Little Ladybirds’, in containers for a pretty splash of color on the patio. Because cosmos is so easy to grow, it is a fun choice for a children’s garden.

genus name
  • Cosmos
  • Sun
plant type
  • Annual
  • 1 to 3 feet,
  • 3 to 8 feet
  • 1-2 feet wide
flower color
  • Red,
  • Orange,
  • White,
  • Pink,
  • Yellow
foliage color
  • Chartreuse/Gold
season features
  • Fall Bloom,
  • Summer Bloom
special features
  • Low Maintenance,
  • Attracts Birds,
  • Good for Containers,
  • Cut Flowers
  • 2,
  • 3,
  • 4,
  • 5,
  • 6,
  • 7,
  • 8,
  • 9,
  • 10,
  • 11
  • Seed


Cutting-Garden Essential

Pair cosmos with three or four other easy-to-grow annuals and enjoy weeks of freshly cut flowers right from your own garden. Anchor the cutting garden with multiple varieties of cosmos. Try ‘Cupcake White’ or ‘Psyche White’ along with the ‘Sonata’ mix in white, pink, rose, and cherry. You may also want to include other annuals like zinnias, sunflowers, larkspur, bells of Ireland, and bachelor’s buttons.

For a low-maintenance cutting garden that is low-cost, too, grow cutting flowers from seeds planted in rows. The row-style planting makes it easy to manage weeds. A $15 investment in seeds will yield armloads of flowers in multiple varieties.

Share your passion for gardening with your kids using these ideas!

Cosmos Care Must-Haves

This tough warm-weather annual likes average, well-drained soil in full sun. (Avoid soil that is rich and fertile.) Make seed-starting even easier by directly sowing cosmos in the garden just before the last frost date in spring. Sow seeds 2 to 3 inches apart and ¼ inches deep. Cover with fine soil. Seedlings will emerge in 5 to 10 days. Keep the seed bed well weeded and watered. Cosmos will begin blooming about two months after planting. If you prefer to start seeds indoors, do so 6 to 8 weeks before the last frost date in spring.

Plants that come from tall cosmos varieties should be spaced close to each other for support. They still may need staking. Use tall bamboo stakes and garden twine to support plants quickly and easily. Deadhead spent flowers to encourage plants to unfurl new flowers. Leave some flowerheads for self-seeding, if desired. When planted in the garden, cosmos does not need fertilizer. Plants growing in containers flower best when fertilized every two weeks or so with an all-purpose garden fertilizer.

What is deadheading? Find out here.

Colorful Combinations

Depending on the variety, cosmos features single saucer-shape flowers with yellow centers and white, pink, or red rays. This annual’s green leaves are deeply cut into feathery threadlike segments. Cosmos cultivars sport a larger number of colors than regular cosmos—including bicolor—expressed in single, semi-double, or double flowers. Look for sizes ranging from dwarf to tall.

More Varieties of Cosmos

‘Sonata White’ cosmos

Cosmos ‘Sonata White’ bears pure-white flowers on sturdy, 18-inch-tall plants.

‘Cosmic Yellow’ cosmos

Cosmos sulphureus ‘Cosmic Yellow’ is a compact selection with double yellow flowers over dark green foliage. It grows 12 inches tall.

‘Cosmic Orange’ cosmos

This cultivar of Cosmos sulphureus bears many double orange flowers that are great for cutting. It grows 12 inches tall.

‘Sensation’ cosmos

This Cosmos mix bears large, 4-inch-wide flowers in a mix of lavender, pink, red, and white on plants that can reach 5 feet tall.

‘Versailles’ cosmos

This Cosmos variety is especially good for cutting because of its strong stems and large flowers in shades of pink, white, and red.

Yellow cosmos

Cosmos sulphureus bears orange, yellow, or red flowers and finely divided foliage.

‘Candystripe’ cosmos

Cosmos bipinnatus ‘Candystripe’ has pure white petals edged in deep pink. It reaches 3 to 5 feet tall. Zones 2-11

Plant Cosmos With:

There are few flowers as showy as celosia. Whether you plant the plumed type, which produces striking upright spires, or the crested type, which has a fascinating twisted form, you’ll love using celosia in bouquets. The flowers are beautiful fresh, but you can also dry them easily. And they bloom in all the colors of a glowing sunset.Plant established seedlings in spring after all danger of frost has passed. Celosia likes rich, well-drained soil with moderate water. Spider mites can sometimes be a problem in hot, dry weather.Shown above: New Look celosia

Dusty miller is a favorite because it looks good with everything. The silvery-white color is a great foil for any type of garden blossom and the fine-textured foliage creates a beautiful contrast against other plants’ green foliage. Dusty miller has also earned its place in the garden because it’s delightfully easy to grow, withstanding heat and drought like a champion.

There are few gardens that don’t have at least one salvia growing in them. Whether you have sun or shade, a dry garden or lots of rainfall, there’s an annual salvia that you’ll find indispensable. All attract hummingbirds, especially the red ones, and are great picks for hot, dry sites where you want tons of color all season. Most salvias don’t like cool weather, so plant them outdoors after all danger of frost has passed.

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