Growing Guide on Cosmos Sulphurous | Sulfur Cosmos Care

Last Updated: 18.10.2023
Written by
Chandrima, a flower enthusiast and writer at India Gardening with over 5 years of content writing experience. She combines her love for flowers with her background in gardening and literary expertise to create informative content. In addition to her passion for gardening, she's an aspiring traveler and nature lover.

Cosmos sulphureus showcases lovely yellow flowers that can be a great addition to the garden! Here’s how to grow it!

Cosmos sulphureus


sulphureus is also popular by the names Yellow Cosmos and Sulfur Cosmos. It is a species of flowering plant native to Mexico and grows quite well in the Indian climate too!

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Cosmos Sulphureus Information

Cosmos sulphureus is a species of flowering plant in the Asteraceae family. It is native to Mexico and parts of Central and South America. It is commonly known as the sulfur cosmos or yellow cosmos due to its bright yellow, orange, or red flowers.

The plant typically grows to a height of 2-4 feet and has feathery, fern-like leaves. The flowers are daisy-like with a single row of petals and a central disk, and they bloom from mid-summer until the first frost. The flowers are popular with bees, butterflies, and other pollinators.

Cosmos sulphureus is an annual plant that is easy to grow and care for. It prefers full sun and well-drained soil and can tolerate drought conditions. It is often used in flower beds, borders, and wildflower gardens, and it also makes a great cut flower.

How to Grow Cosmos sulphureus?

Here are some general tips on how to grow Sulfur Cosmos from seeds:

  • Collect the seeds: Wait until Cosmos sulphureus flowers have faded and the seed heads have dried out on the plant. Then, collect the seeds by gently shaking the seed head or by snipping them off with a pair of scissors.
  • Prepare the soil: Choose a well-draining potting soil and fill a container with it. Make sure the container has drainage holes in the bottom.
  • Sow the seeds: Sow Cosmos sulphureus seeds on the surface of the soil and cover them with a thin layer of soil. Lightly water the soil to moisten it.
  • Provide the right conditions: Place the container in a warm, bright location that receives at least 6 hours of sunlight per day. Keep the soil moist but not waterlogged.
  • Transplant the seedlings: Once the Cosmos sulphureus seedlings have developed their first set of true leaves, they can be transplanted into larger pots or directly into the garden. Harden off the seedlings by gradually exposing them to outdoor conditions before planting them in the garden.

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Requirements to Grow Cosmos sulphureus

Cosmos sulphureus 2


Sulfur Cosmos needs full sun to thrive, meaning at least 6 hours of direct sunlight daily. It can tolerate shade, but its growth and flowering will improve in full sun.


The plant prefers well-draining soil with a neutral to slightly alkaline pH. Sulfur Cosmos can tolerate many soil types but will do best in loose, well-drained soil with good organic matter content.

If the growing medium is heavy, amend it with compost, sand, or other materials to improve drainage.


When growing Cosmos sulphureus, make sure you water the plant only when the topsoil goes a little dry to the touch. Do not water the plant on a daily basis.


Cosmos sulphureus is an annual plant that prefers warm temperatures. Sulfur Cosmos can tolerate some frost but will not survive a hard freeze. The optimal temperature range is between 15-32°C (60-90°F).

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Cosmos sulphureus Care


Cosmos sulphureus doesn’t require a lot of feed, but a light application of a balanced fertilizer (such as 10-10-10) can help promote growth and flowering. Do it once in 2-3 months for best results.


Sulfur Cosmos doesn’t require much pruning, but deadheading spent blooms will encourage more flowers to form. You can also pinch back the tips of the plants when they are young to encourage bushier growth.

Pests and Diseases

It is generally free of serious pest and disease problems. However, the plant can be susceptible to fungal diseases such as powdery mildew, which can be prevented by providing good air circulation around the plants and avoiding overwatering.

Aphids, spider mites, and whiteflies may also attack the plants, which can be controlled by washing them off with a strong stream of water or using insecticidal soap.

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Advantages of Cosmos sulphureus

  • It produces bright, colorful flowers in shades of yellow, orange, and red, adding beauty and visual interest to your garden.
  • It is a hardy, low-maintenance plant that is easy to grow from seed. It can tolerate many growing conditions and is a good choice for beginner gardeners.
  • Once established, Cosmos sulphureus is drought-tolerant and can handle dry conditions, making it an excellent choice for gardeners in hot and dry climates.
  • The bright, showy flowers of Cosmos sulphureus are attractive to bees, butterflies, and other pollinators, making it an excellent choice for gardeners looking to support pollinator populations.
  • Cosmos sulphureus make for an excellent cut flowers and can create beautiful bouquets and arrangements.
  • The plant contains a natural insect-repellent compound, pyrethrin, which can help keep pests like mosquitoes and other flying insects at bay.
  • Cosmos sulphureus has a long blooming period, typically from midsummer to fall, providing a stable source of color in your garden.

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