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Green Valley Supply's Gardening Encyclopedia

Cosmos Bipinnatus (Garden Cosmos)

Cosmos Bipinnatus (Garden Cosmos)

Cosmos bipinnatus Flowers

Cosmos bipinnatus Flowers

KENPEI, Cosmos bipinnatus7, CC BY-SA 3.0

What is Cosmos bipinnatus?

Also known as Mexican aster or garden cosmos, Cosmos bipinnatus is a herbaceous flowering plant. The mid-sized plant is native to Mexico. Cosmos varieties, species or cultivars are used as ornamental plants. The popular flowering plants thrive in temperate climatic regions.

The plant also grows in the West Indies, South and North America, Australia, Italy and Asia. It also grows in other regions across the world as a weed.

Cosmos Etymology

Cosmos is a Greek word for orderliness. It's beauty is compared to an ornament and the universe for its arrangement. The Cosmos genus is made up of about 20 plant species with Mexican roots.

Cosmos bipinnatus Description

The plant is a partially-hardy annual with a tendency of self-sowing for many years. It grows in height up to four feet. Cultivated Cosmos varieties feature purple, pink and white flowers. It has thread-like foliage and flowers heavily.

Cosmos bipinnatus Leaves

Cosmos bipinnatus Leaves

Photo by and (c)2006 Derek Ramsey (Ram-Man), Cosmos bipinnatus 'Double Click' Leaves 1600px, CC BY-SA 2.5

Cosmos bipinnate leaves interlock when grown together for support, eliminating the challenge of plant tops being bulky with flowers.

Cosmos bipinnatus Species

Some popular Cosmos bipinnatus varieties for cultivation are as follows:

  • Daydream with pink flowers on the inside and white flowers on the outside.
  • Sensation Pinkie
  • Seashells with quilled flower petals
  • Versailles - short species grown for cut flowers
  • Sonata series

Cosmos bipinnatus Cultivation

The plants thrive in alkaline soils with a 6 to 8.5 pH. They require moderate temperature for growth and take about 7 to 10 days to germinate. Cosmos plants first flower from two to three months after germination. They're shade-tolerant and bloom in the full sun.

The plant stems are delicate and thus don't require excessive rain because it can lead to plant breakage. It's heat tolerant, but has poor tolerance to strong winds, droughts and cool temperatures. They grow up to 4 feet high upon maturity.

The plants lure slugs, snails and aphids, making up the common pests. Honey bees, butterflies and birds are the major plant pollinators. Cultivated varieties are annual or perennial herbaceous flowering plants.

Honey Bee Pollinating a Cosmos Flower

Honey Bee Pollinating a Cosmos Flower


Uses of Cosmos bipinnatus

Cosmos plants are ideal for butterfly gardening and ornamental use.

Other Cosmos Varieties

Other popular Cosmos species include the following:

  • Cosmos carvifolius
  • Cosmos atrosanguineus
  • Cosmos longipetiolatus
  • Cosmos caudatus
  • Cosmos sulphureus
  • Cosmos parviflorus
  • Cosmos sherffii
  • Cosmos pacificus
  • Cosmos ochroleucoflorus

Plant Cosmos bipinnatus at Home

You can grow Cosmos bipinnatus from seeds in a raised bed and transplant them in  a grow bag for easy placement around your garden.

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