Cosmos Growing Guide

All you need to know to grow successfully!

Plant Family:
Plant Type:
Growing Difficulty:
Typical Zones Grown In:
4, 5, 6, 7, 8, 9, 10, 11

Planting Depth:

6-12 mm
Maturity Time:
40-60 days
Companion Plants:
Zinnia , Marigold

Planting Guidelines

The following are general guides to follow. However, nothing is set in stone. Feel free to experiment!

How to Start:
Direct Sow or Start Indoors if you want an extra challenge
When to Direct Sow:
May, June, July
Sprouting Time:
7-14 days
Spacing (cm):
20 cm
Row Spacing (cm):

Square Foot Spacing:

4 Plants
Sun Exposure:
Full Sun
Typical Season:
When To Harvest:
July, August, September, October
How to Harvest:
Cut stems off

Tips to Growing Organically

Growing without the use of pesticides and herbicides is easier than you may think and it’s better for the environment!

Companion Plants:
Zinnia , Marigold
Common Pests:
Aphids, Whiteflies, Spider Mites
Common Disease:
Downy Mildew, Root Rot
Bonus Grow Tips:
Plant in sunny location, harvest flowers when they are fully open

Cosmos is a popular garden flower that produces showy blooms in shades of pink, white, and red. It is a member of the Asteraceae family and is native to Mexico and some parts of South America. Cosmos plants are easy to grow and can reach up to 6 feet in height. They bloom from mid-summer to early fall and attract bees, butterflies, and other pollinators to the garden. Cosmos can be grown in containers, beds, or borders, and make excellent cut flowers. They prefer full sun and well-draining soil, and are drought-tolerant once established.

How to Grow Cosmos Organically

  1. Choose the right time: Cosmos are warm-season annuals that should be planted in the spring after the last frost date in your area.
  2. Select a location: Cosmos prefer full sun and well-draining soil. They can tolerate a variety of soil types, including sandy or clay soils.
  3. Prepare the soil: Loosen the soil to a depth of 6-8 inches and remove any rocks or debris. Add compost or aged manure to the soil to improve soil fertility and drainage.
  4. Plant the seeds: Cosmos are usually grown from seed. Sow the seeds about 1/4 inch deep and 12-18 inches apart. If you’re planting a large area, consider using a seed spreader.
  5. Water the plants: Keep the soil evenly moist, but not waterlogged. Water the plants deeply once or twice a week, depending on the weather.
  6. Fertilize the plants: Cosmos do not need a lot of fertilizer. You can add a light application of balanced fertilizer, such as 10-10-10, once or twice during the growing season.
  7. Control pests and diseases: Cosmos are generally pest and disease-free. However, they can attract aphids and spider mites. Use organic methods like neem oil or insecticidal soap to control pests.
  8. Deadhead the flowers: Deadheading is the process of removing spent flowers to encourage more blooms. Pinch off the spent flowers at their base to promote new growth.
  9. Support the plants: Cosmos can become top-heavy and flop over without support. Use stakes or cages to keep the plants upright.

Following these steps will help you grow beautiful, colorful cosmos in your garden. Cosmos are often used in floral arrangements and can also attract pollinators to your garden. There are many different colors and varieties of cosmos to choose from, each with their own unique characteristics.

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