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Cosmos are flowering plants that have freely-growing flowers annually. The plants are not difficult to grow, some reaching full maturity in a span of three months. For those who are looking to get a flower that will remain in bloom for many months, the cosmos flower is just that. It is so simple to grow, that you can just scatter seeds after winter frost has disappeared and cosmos will begin its life.

Flowers are perched on long and slender stems, forming a colorful cloud that looks appealing in summer. Cosmos not only attracts human admirers, but bees, birds and butterflies absolutely adore these plants. Cosmos of the garden variety is native to Mexico and the Southwest of the USA.

Cottage Garden Cosmos

Quintessentially, cosmos flowers are suited to a cottage garden and blend well with any other plants. Cosmos comes in tall varieties that look great in the center of a border, or at the ends. Flowers that have spiky appearances such as agastache and goat’s beard look good with accents of cosmos. Other beautiful flower mixes with cosmos are Black-eyed Susans and coneflowers. The shorter varieties of cosmos are ideal to show off as airy, colorful plants on edges and sides.

Daisy-like, with florets that resemble rays, flowers have central floret discs, as if like a cup that is shallow. Cosmos blooms in a wide variety of colors, with more to choose from year in and year out. Flower heads have widths from 10 to 15 mm. Leaves are arranged in an opposite way and are compound (two or more leaflets). Each leaf blade has lengths of 60 to 100 mm. They are lobed deeply, bipinnate and feather-like or pinnate, according to the sub-type of the flower. It’s a good thing that cosmos is resilient to pests, and look good throughout the blooming season.

A Glimpse of Cosmos Ideal Growing Conditions

Here’s an overview of Cosmos’s breed and growth information:

  • Cosmos flowers have the botanical names of sulphureus cosmos and bipinnatus cosmos
  • The flower blooms on an annual basis with heights of 1 to 6 feet when matured. Spreads go up to 3 feet.
  • Plants have to have full sunshine and soil that is drained out properly, but moist. Soil pH should be at 6.0 to 6.7 levels and very mild acidic soil is required.
  • Flowers come to full bloom in summer and fall.
  • You get a range of colors from Magenta, white and pink to yellow, red, orange and chocolate. Some blooms are bi colored as well.
  • You’ll find these flowers flourishing in Mexico and other parts of Southern America.

Growing Cosmos

Cosmos flowers grow very easily in flower beds. Due to their long, narrow stems, they make really lovely cut flowers and will last in a vase. Fully grown Cosmos is able to handle drought, soil conditions that are poor, and even being neglected. People who work and can’t tend to them regularly love them for precisely this reason. They are robust. What’s more, Cosmos can self-sow. In the southeast of the USA, Cosmos sulphureus is an invasive variety of the plant. It hampers plant growth of other blooms and can take over a garden rather fast.

Overall, Cosmos isn’t high on maintenance. Pests such as fleas, aphids, thrips and beetles tend to damage Cosmos. Nonetheless, these are easily got rid of with strong water sprays and pesticide soaps. Powdery mildew, bacterial wilt and Aster yellow are growths that can adversely affect cosmos sometimes. Plants should be spaced appropriately so that they have room to breathe and grow freely without interference.

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Soil Requirements

Cosmos plants need mildly acidic to neutral soil to grow in. This ensures optimal growth of the plant and results in the best Cosmos flowers. Still, plants are tough enough to grow in poor conditions of soil in which other flowers would wilt. Soil should be of a level of medium moisture, yet drained well. Nonetheless, Cosmos uniquely grows in drier soil too. If soil is too rich in nature, plants may grow to elaborately tall heights and stoop. Eventually, they will flop over and languish. A way to avoid this situation is to stake plants, so they get support. Another way to prevent plants from falling over is to plant them near other plants, so they get support. Just keep a watch that they don’t get invasive if they’re much too close to other plants and flowers.


Cosmos thrives in warm to hot weather. It even withstands tropical weather and can take any level of humidity.


To grow the best Cosmos flowers, select spots that get a great deal of sun. This plant likes full sunshine. Partial shade will also do for this strong plant, but you will see a reduced number of blooms. Also, in some shady areas, Cosmos’s growth doesn’t tend to be as vigorous as it does in complete sunshine. The hottest weather with uninterrupted sun is the perfect comfort zone for Cosmos. In arid locales like those of Central and Southern America, Cosmos grows vibrantly. Mexico is famously known for this flower in all its vivid hues. Countries that have the same conditions are great homes for Cosmos.

Watering Cosmos

After Cosmos has reached its full blooming stage, there’s no need to water plants at all. Unless a prolonged drought condition exists, your Cosmos can do without water. In areas where water is scarce, these plants are the last to diminish for lack of water.

Applying Fertilizer

Cosmos doesn’t need any kind of fertilizer. Unless your plants are suffering, you can just ignore the use of fertilizer. Cosmos is okay with poor soil. Unnecessary use of fertilizer will actually have an adverse effect on the plant. In case you do use it, you will grow plants with abundant foliage but limited Cosmos flowers. Remember that these flowers are magnets for insects such as lacewings, tachinid flies and parasitic wasps that feed on many pests and actually protect the flowers. They provide beneficial pollination and protect valuable flora.

Trimming and Pruning

All that cosmos plants need in terms of pruning is deadheading. This will prolong the plant’s blooming season. In the event you forget to trim in time, you can always shear the plants by a third of their size. Do this when most of the blooms have faded away. As a result of this, you will see a second wave of flowers and foliage.

Cosmos Propagation

These plants display so much convenience, it’s hard not to love them! They are readily self-seeding flora. If you collect the seeds that have dried at the end of the season, you can save them until the following one to replant. It’s important to note that seeds that come from hybrid cosmos varieties may not turn out like the parent plant. In such cases, plants may revert to one of the original species.

Cosmos from Seeds

You can get cosmos flower seedlings in any nursery. This makes little sense if you are already growing cosmos. You can use seeds of your plant by starting seeds indoors, around five weeks before the last frost occurs. You can also sow seeds directly outdoors and the plant will start its growth rapidly. Seeds will germinate between 7 and 21 days at a temperature of 75 degrees Fahrenheit. Flowering will follow in the next 50 days or so. You’ll notice that seed packets advise very exact spacing of planting, like a 2-foot distance between plants. Scattering seeds gives a better display though. Plants tend to support each other as they develop. Let the last frost die down completely as this can kill plants if it comes about.

Cosmos Varieties

Two kinds of cosmos flowers are common to gardens. Cosmos sulphureus is typical of regions in Mexico, the northern part of South America and Central America. These flowers are a bright golden yellow hue, tolerant of arid conditions and hot weather. Growing as tall as 6 feet, with a minimal height of 2 feet, the plant grows double florets. Some flowers may be orange as well. The other popular flower is that of Cosmos bipinnatus. These are flowers that look like daisies and come in white, pink, red and orange hues. Hybrid flowers are grown from this cultivar of the cosmos flower. Not as tolerant of heat as their Mexican relatives, they can stand very sunny weather.

Popular Flowers

Some very sought-after cosmos cultivars are the following ones:

  • Blend of “Bright Lights” – This is a hybrid mix of all the brightest nature colors and flowers come in ravishing yellows, golds, reds and orange colors.
  • “Cosmic Orange Flower” – This flower in a dual orange mix is vibrant and bright. It has an awesome tolerance for drought-like conditions.
  • Series of “Seashells” – A cosmos flower with tubular petals and flowers that are a mix of pastel pinks and peachy shades.
  • “Peppermint Candy” Cosmos – A distinct award-winner, this variety has petals that are white with magenta splashes of color.
  • Variety of “Chocolate Cosmos” – This is a unique variety called Cosmos astrosanguineus by its botanical name. This is much-loved as a perennial plant. People adore it because, believe it or not, it actually has the scent of rich cocoa. It is a hardy cultivar, but needs more care than other varieties. Unlike its counterparts, it can tolerate the cold better than the heat, but doesn’t do badly under sunlight. Like dahlias, these cosmos flowers grow and bloom from tubers.