Cosmos (Cosmos bipinnatus) will provide a pop of floral color in a landscape area that has poor soil. As a hardy member of the daisy family, cosmos thrives in soil and environmental conditions that other plants cannot.
So how do you grow Cosmos? Self-seeding and easy care cosmos is a great plant for difficult landscape areas or areas that you don’t want to regularly maintain. Use these growing tips and start your own colorful crop of cosmos this spring.
Planting Location
A full sun location is best but this annual will perform well almost anywhere. Sow seeds directly into soil after all danger of frost has passed.
Thin seedlings 12 inches (30 cm) apart and in less than 10 weeks you will have an abundance of bright candy-colored blooms. Depending on the variety planted, cosmos will reach a mature height of between 1-6 feet (30 – 180 cm).
After Care
Cosmos does best without being fed. If the soil is too rich, these annuals won’t reach their full growth and color potential.
Water cosmos only during times of severe drought. These hardy flowers are drought-tolerant and grow well in dry, arid climates.
Taller varieties will need a structure to help support them during heavy rains and high winds.
Plant cosmos next to a fence, trellis or tie them up to stakes that are as tall as the expected mature height.
Dwarf or compact types of cosmos grow well in containers indoors or outdoors. Place container in a sunny location and keep soil moist.
If plants become leggy they need more direct sunlight.
Bloom Time
Bloom time goes from early summer until late fall/autumn. Deadhead spent blooms throughout the growing season to encourage more blooms.
Blooms resemble a daisy bloom and can have single or double petals. Bloom size will be 3-5 inches (7 – 12 cm) across. Colors range from red, white, purple, yellow, pink, or orange and attract a variety of birds, butterflies, and bees.
Cosmos is self-seeding and will return next year with new plants. To encourage the plant to re-seed itself, leave some of the spent flower heads on the plants at the end of the season. Do not disturb the soil during the winter or in spring. When the soil warms up in spring, the flower seeds will germinate and a new crop of cosmos will spring up.
Regions that have warm winters can have cosmos blooming year-round.
You might be interested in reading my other post about “What Flower Seeds Should I Sow in February?“.
Plant facts
| Genus | Cosmos |
| Light | full sun |
| Soil type | chalk, loam, sand |
| Soil drainage | moist but well drained |
| Height x Width | 1~8 x 1~2 feet (30~240 x 30~60 cm) depending on type |
| Flowering seasons | Summer, Autumn/Fall |
| Life span | half hardy annual, perennial |
| Plant hardiness zones | 2 – 11 |
What Flower Seeds Should I Sow in February?
