Botanical Information and How to Grow Cosmos
Botanical and Common Name: Cosmos flowers are called by their scientific names.
Plant Category: Most cosmos plants are annuals but some are considered tender perennials.
Bloom Time and Color: Cosmos flowers appear in late summer and will last for weeks, often until the first frost. The bright, colorful flowers of Cosmos are highly attractive.
Foliage: Cosmos plants have fine cut foliage that lends an airy feel to the garden and provides a backdrop for the tall flowers on their wiry stems.
Growth Habit: Cosmos have a bushy growth habit and some of the taller forms can tend to sprawl a bit without staking.
Dimensions: Cosmos plants can reach as tall as 4-6' but other forms only grow to 18” tall so be sure to check which species and cultivar you are purchasing.
Preferred Conditions: Cosmos prefer full sun and are heat-resistant. Provide medium to poor soil since Cosmos plants grown in soil too rich will be lanky with weak stems. Once established Cosmos plants are moderately drought tolerant and do best in well-drained soil making them good choices for container plantings.
Maintenance: Cosmos plants require very little maintenance unless the variety is a taller one that needs staking. Many gardeners report seedling volunteers if seedheads are allowed to ripen rather than dead heading Cosmos plants.
Pests or Diseases: Cosmos plants do not have any real threats from pests and disease.
Propagation Methods: Cosmos are easy to grow from seed and while they are ready self-sowers the seedlings will not always grow true to seed.
Using Cosmos Plants in the Garden Landscape
Companion Plants: Cosmos plants do well with other sun-loving annuals and drought-tolerant perennials like Echinacea, Zinnia, Lavender, Dianthus, Rosemary, Sweet Potato Vine and Thyme.
Seasons of Interest: Cosmos provides great interest in late summer through fall seasons when many other flowering annuals wane.
Uses in the Garden: Cosmos has so many uses in the garden because it is deer-resistant, drought-tolerant, an excellent cut flower, great for a kids garden because of it's large bright flowers, and is attractive to butterflies. Heirloom varieties are readily available and cosmos is a great addition for cottage garden plantings as well.
Varieties and Cultivars of Cosmos Plants
Garden Cosmos (Cosmos bipinnatus): Generally taller forms up to 6' tall with smaller flowers about 2” wide these Cosmos are native to Mexico. Many cultivars are available.
- Sonata Series: A dwarf form about 18” tall with flowers available in white, pale pink, and other solid colors.
- Sensation Series: About 3' tall these cosmos have several named colors including red, white and yellow.
- Daydream Cosmos: A bi-colored Cosmos that grow 4' tall, the Daydream cosmos has white petals with a dark crimson center.
Yellow Cosmos (Cosmos sulphureus): More dwarf forms are available and the foliage can sometimes be less finely-cut than C. bipinnatus.
- Ladybird Scarlet Cosmos: Bright orange-red flowers on compact growth this Cosmos grows to about 20” tall and have brilliantly colored flowers.
- Cosmic Red: Part of the Cosmic Series, this Cosmos has true red colored flowers on compact 15” tall stems.
- Klondike or Sulphur Cosmos: Orange and yellow-orange flowers that grow to 24-36" tall.
Chocolate Cosmos (Cosmos atrosanguineus): Deep burgundy colored flowers with rich chocolate scent making them a great choice for fragrant garden beds. C. atrosanguineus is hardier than some of the other cosmos species and will often survive winters to zone 6 . Chocolate cosmos will also tolerate richer soil as well.
Angela England - Angela England is a problogger, mother of four (yes I know what causes that), speaker, teacher, labor doula, gardener and so much more.
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