Sea Shells Mix

Family: Asteraceae Annual flowering plant

Planting Schedule

Provide your location or planting zone to unlock dates and add Sea Shells Mix to a garden.

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.

Light: Full SunMaturity: 60 DaysHabit: Upright

Botanical illustration of Sea Shells Mix

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Sea Shells Mix Planting Dates by USDA Zone

Estimated US hardiness-zone windows for sow, transplant, and harvest. Enter a US ZIP above for exact local dates, or open a zone below.

Zone	Start Indoors	Sow / Transplant	Harvest
Zone 1a	Protected Environment Only
Zone 1b	Direct Sow	Jun 1st	Jul 31st – Aug 1st
Zone 2a	Direct Sow	May 25th	Jul 24th – Aug 29th
Zone 2b	Direct Sow	May 15th	Jul 14th – Aug 25th
Zone 3a	Direct Sow	May 15th	Jul 14th – Sep 1st
Zone 3b	Direct Sow	May 19th	Jul 18th – Sep 21st
Zone 4a	Direct Sow	May 15th	Jul 14th – Sep 24th
Zone 4b	Direct Sow	May 13th	Jul 12th – Sep 27th
Zone 5a	Direct Sow	May 8th	Jul 7th – Sep 30th
Zone 5b	Direct Sow	May 4th	Jul 3rd – Oct 5th
Zone 6a	Direct Sow	May 1st	Jun 30th – Oct 10th
Zone 6b	Direct Sow	Apr 25th	Jun 24th – Oct 16th
Zone 7a	Direct Sow	Apr 20th	Jun 19th – Oct 20th
Zone 7b	Direct Sow	Apr 10th	Jun 9th – Oct 28th
Zone 8a	Direct Sow	Apr 1st	May 31st – Nov 5th
Zone 8b	Direct Sow	Mar 23rd	May 22nd – Nov 12th
Zone 9a	Direct Sow	Mar 6th	May 5th – Nov 26th
Zone 9b	Direct Sow	Feb 9th	Apr 10th – Dec 9th
Zone 10a	—	Oct 1st	Nov 30th – Feb 28th
Zone 10b	—	Oct 1st	Nov 30th – Feb 28th
Zone 11a	—	Oct 1st	Nov 30th – Feb 28th
Zone 11b	—	Oct 1st	Nov 30th – Feb 28th
Zone 12a	—	Oct 1st	Nov 30th – Feb 28th
Zone 12b	—	Oct 1st	Nov 30th – Feb 28th
Zone 13a	—	Oct 1st	Nov 30th – Feb 28th
Zone 13b	—	Oct 1st	Nov 30th – 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.