Cosmos are renowned for their profusion of blooms from late spring until fall, and they are especially lovely when grown closely together to create a backdrop in the garden. These lovely flowers are also attractive to birds, butterflies and beneficial insects, and the benefits of growing these flowers have only just begun!
Native to Mexico and South America, it is said that Cosmos were grown by Spanish priests in their mission gardens, and that they were the ones who named the flowers after the Greek work “kosmos” which means harmony or ordered universe. The evenly spaced and orderly petals inspired the name. Cosmos are said to symbolize balance and harmony.
Cosmos belongs to the vast family of plants known as Compositae. There are approximately 25 known species of Cosmos, but two annual species are the most familiar to the home gardener:
Cosmos sulphureus – also known as Sulphur Cosmos, Yellow Cosmos, Orange Cosmos, Klondike Cosmos
In this species the blooms are always in shades of yellow, orange or red, and the leaves are long with narrow lobes and slightly hairy margins. The blooms can be 2 to 3 inches in width and daisy-like in appearance. Native species can reach 4 to 7 feet in height, but the cultivated varieties are not as tall, usually ranging from 1 to 3 feet.
Cosmos bipinnatus – also known as Garden Cosmos, Tall Cosmos, Mexican Aster, Cut Leaf Cosmos
This species has 2 – 3 inch white flowers or flowers in shades of lavender, pink and maroon, and the leaves are finely cut, appearing almost threadlike. The foliage looks similar to ferns and has a very lacey appearance. Height can vary from 1 to 6 feet. There are many cultivated varieties offering different heights, colors, and variation in blooms such as double and picotee.
Annual Cosmos are considered to be an easy to grow from flower seeds. Choose a location that receives 8 hours of direct sun. Cosmos will grow in partial shade but the number of blooms will be less. Sow Cosmos seeds directly outdoors in the spring once soil temperature is at least 65° and danger of frost is past. Prepare the soil by raking through to loosen it and remove weeds, scatter the flower seeds, rake them under no more than 1/16 inch, and keep the soil moist. The Cosmos seeds usually germinate in 7 to 21 days. Early pinching of the seedlings will encourage branching and will increase the density of the plants. Blooms usually appear in 2 to 3 months after seeding.
Rich, fertile soil is not needed for growing Cosmos but well-draining soil is. Excess fertilization of Cosmos will produce lots of foliage but few blooms. Water sparingly after seedlings emerge, but water deeply to make the plants more drought hardy. Cosmos will self-seed but they are not considered to be aggressive. Deadhead the spent blooms to prolong the flower display. The plants can be cut back to 12 to 18 inches and will re-bloom in about 30 days. The stems can be somewhat weak, so staking may be required and some protection from wind especially for the taller cultivars.
Cosmos plants grow under the worse conditions, yet they provide beautiful blooms that provide nectar for butterflies and make excellent cut flowers. It’s best to cut the flowers in the morning and then immediately place them in tepid water. Remove the foliage from the stems before arranging. Cosmos also can be preserved nicely.
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Native to Mexico and South America, it is said that Cosmos were grown by Spanish priests in their mission gardens, and that they were the ones who named the flowers after the Greek work “kosmos” which means harmony or ordered universe. The evenly spaced and orderly petals inspired the name. Cosmos are said to symbolize balance and harmony.
Cosmos belongs to the vast family of plants known as Compositae. There are approximately 25 known species of Cosmos, but two annual species are the most familiar to the home gardener:
Cosmos sulphureus – also known as Sulphur Cosmos, Yellow Cosmos, Orange Cosmos, Klondike Cosmos
In this species the blooms are always in shades of yellow, orange or red, and the leaves are long with narrow lobes and slightly hairy margins. The blooms can be 2 to 3 inches in width and daisy-like in appearance. Native species can reach 4 to 7 feet in height, but the cultivated varieties are not as tall, usually ranging from 1 to 3 feet.
Cosmos bipinnatus – also known as Garden Cosmos, Tall Cosmos, Mexican Aster, Cut Leaf Cosmos
This species has 2 – 3 inch white flowers or flowers in shades of lavender, pink and maroon, and the leaves are finely cut, appearing almost threadlike. The foliage looks similar to ferns and has a very lacey appearance. Height can vary from 1 to 6 feet. There are many cultivated varieties offering different heights, colors, and variation in blooms such as double and picotee.
Annual Cosmos are considered to be an easy to grow from flower seeds. Choose a location that receives 8 hours of direct sun. Cosmos will grow in partial shade but the number of blooms will be less. Sow Cosmos seeds directly outdoors in the spring once soil temperature is at least 65° and danger of frost is past. Prepare the soil by raking through to loosen it and remove weeds, scatter the flower seeds, rake them under no more than 1/16 inch, and keep the soil moist. The Cosmos seeds usually germinate in 7 to 21 days. Early pinching of the seedlings will encourage branching and will increase the density of the plants. Blooms usually appear in 2 to 3 months after seeding.
Rich, fertile soil is not needed for growing Cosmos but well-draining soil is. Excess fertilization of Cosmos will produce lots of foliage but few blooms. Water sparingly after seedlings emerge, but water deeply to make the plants more drought hardy. Cosmos will self-seed but they are not considered to be aggressive. Deadhead the spent blooms to prolong the flower display. The plants can be cut back to 12 to 18 inches and will re-bloom in about 30 days. The stems can be somewhat weak, so staking may be required and some protection from wind especially for the taller cultivars.
Cosmos plants grow under the worse conditions, yet they provide beautiful blooms that provide nectar for butterflies and make excellent cut flowers. It’s best to cut the flowers in the morning and then immediately place them in tepid water. Remove the foliage from the stems before arranging. Cosmos also can be preserved nicely.