Organic Rubenza Cosmos Seeds

These elegantly colored flowers are super easy to grow and a favorite of cut flower farmers. They give you bountiful blooms with very little work and pollinators love them too!

Cosmos reseed easily. They grow through the warm season and extend well into the cool season in Zone 9 and 10.

Planting by Zones

Zones 9-10

• Cosmos are fabulous delicate-looking flowers that attract pollinators to the garden. Cosmos grow best in Zones 9 and 10, from spring through late summer; if happy, they may bloom well into the winter!

Zones 2-8

• Grown as an annual. Start seed indoors four weeks before the last frost or direct sow after the danger of frost has passed. 

Planting Cosmos Seeds

• Cosmos seeds are long and pointed on each end. They should be sown close to the surface of the soil. If you start the seeds indoors in trays or starter pots, start seeds in a high-quality seed starting mix. Sprinkle the seed on top of well-moistened soil and cover with 1/4″ of finely sifted soil. Seeds will germinate in 3-10+ days.
• If you wish to direct sow the seeds, plant in well-worked soil that has been finely raked clear of debris. Cover with 1/4″ well-sifted soil.
• Plant in a full-sun location. Cosmos are fuss-free flowers that can thrive in a wide range of soils and conditions.

Growing Cosmos

• This old-fashioned annual flower works well in any garden! Cosmos are easy to grow and make an excellent cut flower. We grow cosmos both for cut flowers and to bring important pollinators to the farm.

Growing Cosmos in Containers

• If you are planting cosmos in containers, make sure your container is at least 10″ deep. Rubenza cosmos grow about 12″ tall, a manageable height for containers. Keep in mind containers will dry out faster because they have more surface area and less soil to hold onto moisture.

Harvesting Cosmos Flowers 

• Cosmos spread joy in the garden and make excellent cut flowers too. Harvest flowers early in the morning and place them directly in a vase of room temperature water for the longest-lasting blooms.

Southern California Pro-tips

• In Zones 9 and 10, cosmos flowers will grow happily from early spring through fall.
• DO NOT overhead water as this promotes disease.
• Cosmos can be grown in relatively poor soil, but they respond well to small compost and fertilizer additions.
• Deadhead spent blooms to encourage more flowers.

Companion Flowers/Crops

• Cosmos grow well with wildflower and cut-flower garden favorites like zinnias, sunflowers, and our wildflower mixes. Plant flowers near your veggie garden to attract pollinators! Shop all our flowers here.
• Do you LOVE cosmos? Try all our cosmos varieties in various sizes and colors: Candy Stripe, Sensation Mix, and Sulphur Dwarf Mix.

Additional Learning Resources

• New to starting crops from seeds? Please watch our Seed Starting Presentation to learn the basics!
• Learn about growing all our crops on our YouTube page!
• Having pest issues? Check out the in-depth information on pests that can be an issue to cosmos flowers at the UC Integrated Pest Management site.

Fill your garden with pollinator plants to attract beneficial insects like bees, moths, and butterflies. Learn more about growing Pollinator Plants in our Garden Wisdom Blog.