It often happens that the best flowers are also easy to grow, and Cosmos is definitely in this category. If you’d like to start a cut flower garden, attract pollinators, or simply add color and texture to your landscape, veggie beds, or borders, cosmos may be exactly what you’re looking for.
Cheat Sheet for Growing Cosmos
- An annual or herbaceous perennial originally heralding from Mexico and parts of North America.
- Cosmos atrosanguineus, or chocolate cosmos, is a popular perennial that is typically propagated from root cuttings.
- Grow annuals from seed or nursery starts.
- Start annuals from seed indoors 4 to 6 weeks before your last spring frost or direct sow in spring after last chance of frost is past. Can be scatter sown in fall in mild climates such as hardiness zones 9 through 11.
- Seedlings grow quickly, so starting seeds indoors plan to pot them up once they’re a few inches tall to encourage continued growth.
- Not too fussy about soil.
- Requires full sun.
- Water moderately when taking hold but it’s possible to reduce watering once mature, though you’ll get more consistent blooms with consistent watering.
- In all honestly, Cosmos can practically be ignored and still continue to thrive.
- Blooms about 7 weeks after germination and continues to bloom until your first all frost.
- Deadhead to encourage blooming.
- Choose from a great number of cultivars that vary in color, shape, and size.
- Protect taller varieties from strong, summer winds with simple stakes, much like you would with dahlias.
- Cosmos are happy to self-sow depending on your climate and in some instances can become weedy. Be prepared to strategically move volunteers for optimal placement and give extras away to friends and neighbors (they’ll love you for it).
Cosmos sulphureus ‘Polidor,’ ‘Fruit Crush,’ ‘Cosmic Orange,’ or ‘Bright Lights’ (top photo) is a mix of bright yellow and tangerine blooms. It’s an annual that grows to about 2 feet tall and produces masses of blooms with semi-double petals that are gorgeous when planted in drifts. This particular species is also edible. Use flowers in salads or as a garnish for a splash of color and try adding young leaves to salads. However, it’s important to note that only Cosmos sulphureus is edible.
Cosmos bipinnatus ‘Lemonade’ (above) is as dreamy as it looks. With a warm, unique way of catching the light, it’s soft yellow blooms pair well with most other hues in the garden. It’s an annual that blooms about 10 weeks after sowing, so start it a little earlier than others with quicker bloom times. Grows about 2 feet in height.
Cosmos bipinnatus ‘Sensation’ produces large blooms often measuring 3 to 4 inches across and can be found in white, pink, and magenta. Another annual, ‘Sensation’ grows to about 4 feet tall or taller.
This particular cultivar has long been a garden favorite, receiving it’s first award as an All America Selections winner is 1936!
Cosmos bipinnatus ‘Cupcakes White’ is an annual cosmos with a twist. The original, 5 free petaled form is now a fusion of petals forming a cup-like shape. You’ll find it has a light, airy appeal that catches the breeze and seems to float above borders and beds. Like ‘Sensation,’ it grows to about 4 feet in height.
Voted in 2016 as the Royal Horticulture Society visitor’s favorite, it’s worth planting to simply see it for yourself.
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