There are few sights that can lift your mood as a meadow full of Cosmoses. Their name comes from the Greek word ‘kosmos’ meaning ‘beautiful’ and indeed, the flowers sit atop long slender stems and form a cloud of colour all summer, attracting bees, butterflies, and birds.
The best part? Cosmoses are rather low maintenance.
Cosmoses are freely flowering annuals in the Sunflower family. They are easy to grow and reach maturity in about two months. Cosmoses bloom quickly after germination and continue to flower through autumn. They are day-sensitive plants that blooms best in late summer when the days get shorter. It can grow one to 6ft in height to 1 to 3 ft in width.
Its botanical name is Cosmos sulphureus/ Cosmos bipinnatus and it is native to central and southern America. There are several varieties like Sonata White Cosmos, Cosmic Yellow Cosmos, Cosmic Orange Cosmos, Sensation Pink Cosmos, Versailles’ Cosmos, Candystripe Cosmos, Chocolate Cosmos etc.
Cosmos flowers look a lot like Daisies. There are more than 25 species of Cosmos and numerous varieties and cultivars. They come in a broad range of colours like golden yellow, white, pink, magenta, orange, yellow, red, chocolate, with more cultivars developed every year. There are even bicolour varieties. The choices don’t end here. Cosmos come with single, semi-double, or double flowers, and in sizes ranging from dwarf to tall. They tend to be invasive.
Cosmoses grow easily in beds and make great cut flowers. When established, the plants can handle drought, poor soil conditions, and general neglect. This is a truly low-maintenance plant.
Light
Cosmoses need at least eight hours of full sun. Too much shade will lead to poor bloom and spindly growth.
Soil and water
Cosmos grows in a wide range of soil types. Soil with average to poor fertility is excellent and soil drainage is a key requirement. Cosmoses are also tolerant of most soil pH levels but grow best in neutral to alkaline soils like pH of 7.0-7.5. Keep the soil moist at all times during the growing period and water as often as needed. Once the plants are established, no watering is required. Cosmoses thrive in dry soil.
Temperature and humidity
The Cosmos is a warm-climate plant native to Mexico that needs temperatures above 16 degrees centigrade. Growth is stunted in temperatures below 12 degrees. It can handle high humidity.
Fertiliser
Do not fertilise Cosmos regularly. This is a plant that thrives in poor soil. Rich soil produces floppy, weak plants, as well as a sparse bloom.
Pruning
It takes seven weeks to its first bloom. After that, your flowers should continue to bloom until the summer. Deadheading (pinching off the dry dead flower heads that contain the seeds) the spent flowers promotes re-blooming. If the plants are getting tall and spindly, cutting them back to half of their height to encourages bushier growth habit.
Pests and problems
The Cosmos is rarely affected by serious pests or diseases. But they attract aphids. Powdery mildew, gray mold, and stem canker are common diseases. Good airflow helps to prevent diseases. While some pests like aphids, flea beetles, and thrips feed on cosmos, they’re easy to control with a strong spray of water or insecticidal soap. Aster yellows and bacterial wilt may also affect cosmos.
Pro tips
- Plant in full sun in well-drained soil. Protect from strong winds.
- Deadhead regularly. This helps encourage new growth and more flowers
- Cosmos can grow quite tall. Provide support stakes that they can lean on.