Xanthos

Cosmos

55d to harvest

Feathery, airy blooms rise like warm sparks above the garden—Xanthos Cosmos opens into luminous, petal-rich flowers that sway with every breath of wind. Expect a delicate, satiny texture and a vivid, show-stopping presence that holds its charm in arrangements, making it a favorite for long-lasting cut stems. Grow Xanthos for a breezy, cloudlike display that turns beds and borders into living color from early summer through fall.

Crop Dates

Growing note: In frost-free Zone 11a, grow this cool-season crop during the cooler dry season (October–February).

Milestone	Date
Start Indoors	—
Climate	Frost-Free Climate
Transplant / Sow Outdoors	Oct 1st
Harvest Begins	Nov 25th
Harvest Ends	Feb 28th

Crop Details

Trait	Value
Days to Maturity	55
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	70
Min Soil Temp (°F)	55
Min Night Temp (°F)	45
Harden Off (days)	7

Frequently Asked Questions

What pest or disease commonly affects Cosmos bipinnatus, and how can I control it?

Cosmos bipinnatus is often troubled by aphids, especially on tender new growth and flower buds. Rinse plants with a strong water jet, then spray insecticidal soap (follow label directions) and repeat every 5–7 days until aphid numbers drop. If you see powdery-white growth on leaves, remove badly affected foliage and increase airflow (thin plants and avoid overhead watering) to slow the spread.

How often should I water Cosmos bipinnatus during peak growth?

During the main growing phase, keep the soil evenly moist but not soggy—water when the top 1 inch of soil feels dry. Cosmos will tolerate some dryness once established, but consistent moisture helps it branch and produce steady flowers, especially in warm weather. Water at the base to avoid wetting foliage, which can encourage leaf diseases.

How can I tell when Cosmos bipinnatus is ready to harvest?

Harvest flowers when the bloom is fully open and the petals are crisp and brightly colored, usually about 55 days from sowing under good conditions. For seed harvest, leave seed heads on the plant until they turn brown and feel dry, then collect them before they shatter. Cut flowers regularly to keep plants producing fresh blooms throughout the season.