Growing Cosmos in Zone 10B

Cosmos are elegant, easy flowers that thrive in poor soil and attract pollinators all season.

Zone 10B has a very long growing season with mild winters. Many crops can be grown nearly year-round with successive plantings.

Top Growing Tips

• Actually perform better in lean soil — don’t over-fertilize
• Direct sow after frost; seeds germinate in 7-10 days
• Tall varieties (4-6 feet) may need staking
• Deadhead to prolong blooming or let self-seed for next year
• Chocolate cosmos has a genuine chocolate scent (but is more tender)

Companion Planting

Good companions: vegetables and herbs — attracts beneficial insects

Avoid planting near: none — cosmos are universally friendly

Harvest Timeline

Flowering in 60-90 days from seed; excellent cut flower

About Zone 10B

USDA Hardiness Zone 10B has an average last spring frost around Jan 15 and first fall frost around Dec 31. All planting dates above are calculated from these frost dates. Your specific location may vary — check with your local extension office for the most accurate dates.