Cosmos bipinnatus
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| Cosmos bipinnatus |
Cosmos bipinnatus, commonly called the Cosmos or the "Mexican Aster", is a medium sized flowering herbaceous plant sometimes grown in gardens.
This species is considered a half-hardy annual, although plants may re-appear via self-sowing for several years. The plant height varies from two to four feet. The cultivated varieties appear in shades of pink and purple as well as white. Its foliage is finely-cut into threadlike segments.
Some of the varieties of Cosmos bipinnatus in cultivation today include:
- Sensation is a widely available mix of tall varieties
- Versailles and Sonata, developed for the cut flower trade, are shorter than the species, with heights remaining below three feet
- Daydream features a pink inner ring on a white background
- Seashells features quilled petals
Growth characteristics of this plant include:
- Germination takes between 7 and 10 days at the optimal temperature of 75 degrees Fahrenheit (24 °C); flowering begins between 60 and 90 days after germination
- It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America
- Flowering is best in full sun, although partial shade is tolerated
- The plant is tolerant to drought after germination, and is seldom subject to insect or disease damage
The flowers of Cosmos attract birds and butterflies, including the Monarch butterfly.

