Floridata Plant Encyclopedia

A Floridata Plant Profile 536 Cosmos bipinnatus

Common Names: cosmos, Mexican aster Family: Asteraceae (aster/daisy Family)
Image Gallery

This is one of the large flowered, dwarf statured cosmos varieties from the 'Sonata Series'.


Imagine bright colorful disks gracefully balanced on long slender stems, imagine lacy foliage, and best of all, imagine a plant that's easy to grow and that thrives even on poor soil! It's not my imagination, it's Cosmos bipinnatus. This tender annual has fine feathery foliage, its pinnate leaves growing to 10 in (25.4 cm) in length. Cosmos will grow 1-7 ft (0.3-2 m) tall depending on variety and growing conditions. The Mexican aster, as this cosmos is also called, has showy solitary red, white, pink or purple flowers that are 2-3 in (5-7.6 cm) in diameter and up to 4 in (10 cm) in some selections. 'Sea Shells' is a variety with flower petals curled on the edges that provides an unusual two toned look.

A foamy green sea of cosmos fronts a chaste tree in Jack's bee and butterfly garden.


Several species of Cosmos and their hybrids are available to gardeners. Most of these, including C. bipinnatus, are native to Mexico and the southwestern United States.


Cosmos like rather lean, well drained, sandy soils. Do not apply large doses of fertilizer as flowering will be suppressed. Except for the dwarf selections, cosmos usually requires staking to hold stems upright. Light: Bright sunlight. Moisture: Needs adequate moisture, water during times of drought. Hardiness: USDA Zones 9 - 10. is cosmos' natural range but cosmos is a popular garden annual in Zones 5 to 10 and will reseed itself in warm winter climates. In cold zones start plants indoors and transplant after danger of frost has past to ensure flowers. Cosmos seedlings are easy to transplant. Propagation: Cosmos is very easy to grow from seed - sow right in the garden in warmer zones. In climates with shorter growing seasons, start indoors and transplant in garden when frost has past.


Use cosmos as a background plant in beds and borders. The dwarf selections like the 'Sonata Series' are great for container plantings where their toughness and showiness can keep the flower show going all through the summer. Cosmos are popular components of wildflower and meadow gardens where seed is planted and left to its own devices to sprout, bloom, seed and sprout the following year. Cosmos is one of the best nectar plants for attracting butterflies to the garden.

The 'Sonata Series' cosmos is a dwarf selection that grows to about 1 ft (0.3 m) and has large flowers in dark rose, pink and pure white.


Cosmos is easy to germinate, has spectacular flowers that are great for cutting and is virtually pest free - these attributes make it great for kids and beginners. Cosmos flowers are also perfect for pressing.

There are a couple other Cosmos species that are grown in the garden, one is C. sulphureus, features 3 in (7.6 cm) flowers in shades of yellow and orange. C. diversifoius is a perennial that grows up to 3 ft (0.9 m) in height and has rose and lavender flowers with gold centers.


Before planting cosmos check with your local county extension office to make certain that it is not invasive in your area.

Jack Scheper 2/22/99; updated 6/3/01, 6/27/03, 10/8/03, 3/7/04, 1/27/05

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Cosmos species profiled on Floridata:

Cosmos atrosanguineus

( chocolate cosmos, black cosmos, perennial cosmos )

Cosmos bipinnatus

( cosmos, Mexican aster )

Cosmos sulphureus

( orange cosmos )

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