Psyche White

Cosmos

70d to harvest

Silken, cloudlike blooms open in a luminous wash of pure white, each daisy face edged with a crisp ring that catches the light like fine porcelain. Psyche White forms airy, upright stems with feathery foliage that moves in the breeze, creating a fresh, weightless texture in the garden. Grow it for long-lasting cut-flower bouquets and for bright, breezy drifts of white in borders where its daisy-like presence stays picture-perfect from early summer through fall.

Crop Dates

Milestone	Date
Start Indoors	Feb 23rd
Last Frost	Mar 23rd
Transplant / Sow Outdoors	Mar 23rd
Harvest Begins	Jun 1st
Harvest Ends	Nov 12th

Crop Details

Trait	Value
Days to Maturity	70
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	70
Min Soil Temp (°F)	60
Min Night Temp (°F)	40
Harden Off (days)	7

Frequently Asked Questions

What’s the most common pest or disease on Cosmos bipinnatus (Asteraceae) and how can I treat it at home?

Cosmos bipinnatus commonly gets powdery mildew, especially in humid weather or when plants are crowded. Water at the soil line (not the foliage), thin seedlings so leaves dry quickly, and remove heavily affected leaves early. If mildew appears, spray a labeled horticultural sulfur or potassium bicarbonate product per the label, repeating as directed because cosmos growth continues for about 70 days.

How often should I water Cosmos bipinnatus during active growth?

During the main growing phase, keep the soil consistently moist but not soggy—aim for watering about 1–2 times per week depending on heat, with deeper soakings rather than frequent light sprinkles. Let the top 1–2 inches of soil dry slightly between waterings to prevent stress and reduce mildew risk. Once plants are established and flowering, continue regular moisture; drought-stressed cosmos often makes smaller blooms and can slow flower production.

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

Harvest when the flower heads are fully formed and the ray petals are open and crisp, typically around 60–70 days after sowing. Cut in the morning, snipping stems just above a leaf node to encourage side branching and additional blooms. If you’re saving seed, leave heads on the plant until they turn dry and brown and the seeds release easily from the center.