Sea Shells Mix

Cosmos

60d to harvest

Feathery, seashell-swirled blooms rise like confetti on airy stems, opening into luminous, daisy-like faces that shimmer in the sun. The petals are satisfyingly crisp and lightly ruffled, holding their shape with a graceful, wind-kissed texture—ideal for bouquets that look fresh and abundant from the first day. Sea Shells Mix is a pollinator favorite with a vivid, mixed palette, perfect for gardeners who want a long season of color and movement in the flower bed.

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 30th
Harvest Ends	Feb 28th

Crop Details

Trait	Value
Days to Maturity	60
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	75
Min Soil Temp (°F)	55
Min Night Temp (°F)	45
Harden Off (days)	Not Required

Frequently Asked Questions

What pest or disease is most likely on Cosmos bipinnatus, and how do I control it?

Cosmos bipinnatus commonly suffers from powdery mildew (white, dusty growth) and occasional aphid outbreaks, especially in warm, humid weather or crowded plantings. Improve airflow by spacing plants and watering at soil level; remove heavily infected leaves early. For aphids, spray plants with a strong jet of water or treat with insecticidal soap, and avoid nitrogen-heavy feeding that can trigger soft, aphid-friendly growth.

How often should I water Cosmos bipinnatus during the main growing phase?

During active growth, water deeply when the top 1 inch of soil feels dry, then let excess water drain—cosmos dislikes staying soggy. Aim for roughly 1 inch of water per week total (from rainfall plus irrigation) during typical conditions, increasing slightly during hot spells and reducing in cool, wet weather. Consistent moisture supports steady flowering, but overwatering encourages mildew.

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

Harvest for cut flowers when the blooms are fully open and the petals are crisp, not limp; new buds should continue forming for about 60 days after sowing. If harvesting for seed, let the flower heads dry on the plant until the seeds are brown and firm, then cut and finish drying indoors before storing. Deadheading spent flowers regularly will keep cosmos flowering longer.