All About Yellow Cosmos

Yellow cosmos belong to the vast family of plants known as Compositae. There are 20 known species of cosmos out of which the two annual species called Cosmos Bipinnatus and Cosmos Sulphureus are familiar to home gardeners and easy to grow. While the former consists of long pink flowers, Cosmos Sulphureus or yellow cosmos is the shorter of the two and sports warm toned flowers. 

Yellow cosmos are generally 3 to 4 inches in diameter, comprising of attractive center flowers that are yellow, and outer petals that range in color from pale yellow to orange. Their leaves are long and thread like in appearance, with very narrow lobes and hairy margins. 

Sunlight Requirements

Requiring full sun, yellow cosmos grow well when planted in an area that receives 8 to 10 hours of direct sunlight. They are also known to grow in temperatures up to 100 degrees F. These warm weather annuals do not have any specific soil requirement other than to be planted in well-drained soil, nor do they need any particular care. Since the seedlings are not winter hardy, spring is the ideal time to plant them, and they can reach a height of 2 to 4 feet depending on the variety grown.  

Growing Cosmos

Growing cosmos in your garden is very easy. Pick a sunny location and prepare the soil by loosening it. You do not need to amend the soil. Scatter the crescent shaped seeds into the soil after the last frost and rake them in gently to prevent them from going too deep. Keep the soil lightly moist for a week. Germination will take between 7 to 21 days. 

Additional Considerations

One reason they do not thrive is because they are over watered or over fed. Water these drought tolerant annuals only when the flowers begin to wilt, and do not provide any shade for them, no matter how hot the weather gets. Fertilizing too frequently will severely reduce flower production.   

Using Yellow Cosmos

Cosmos are great for attracting butterflies to the garden. These sun-loving annuals are also an excellent source of nectar and are frequented by bees. They also attract beneficial insects to the garden, so make sure you scatter them around your vegetable patch. Cosmos make beautiful cut flowers that are used for flower arrangements, decorating any indoor space with their warm inviting hues of yellow, and can last up to a week.  

Yellow cosmos do not need to be deadheaded since dying flowers continue to produce seeds that are picked by goldfinches and scattered all over. These self-seeding annuals thus spare the gardener the need to replant the annuals for next year.  

Cosmos are so easy to grow and maintain while in bloom from May to November that they should be a part of every garden. Not requiring much basic flower care, they can grow easily where soil conditions are poor, provided the climate is hot and dry. They are generally pest free so do not need any insecticide.