Sea Shells Cosmos on a white background.
See Shell Cosmos held in hands on top of yarn ball
Seashell cosmos on yarn
Sea Shells Cosmos on a white background.
See Shell Cosmos held in hands on top of yarn ball
Seashell cosmos on yarn

Cosmos Seeds,
Sea Shells

4.723 ReviewsSKU: #FL247
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Min. 50 seeds

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Description

(Cosmos bipinnatus). Here's something unusual for cottage gardens or for cut flowers: the ray flowers of this charming cosmos are tubular or cone-shaped rather than flat, giving the blooms an intricate look. Three-inch flowers are produced abundantly all summer until frost, in the usual cosmos shades of deep rose, shell pink, and pure, snowy white. Plants reach 3-4 feet; like most cosmos, it tolerates poor and dry soils, hot conditions.

Growing Tips: Sea Shells cosmos is a unique heirloom variety that reaches 3-4 feet. Like most cosmos, it tolerates poor and dry soils, as well as hot conditions. Regular deadheading encourages more blooms. Avoid excessive fertilization, as that can lead to the growth of foliage at the expense of flowers.

Plant Details

Botanical Name
Cosmos bipinnatus
Life Cycle
Annual
Sun Requirement
6–8 hr.
Days to Germinate
7–14
Days to Maturity
60–90
Planting Depth
⅛–¼ in.
Plant Spacing
10 in.
Ideal Temperature
70–75°F
Frost Hardy
No

Growing Guide

When to Grow

Plant cosmos only after all danger of frost has passed, and temperatures remain steady at 70-75 F for optimal germination. Since cosmos are not frost-hardy, it's important to check your local region's last frost date before planting outdoors. Blooming starts about 60-90 days after sowing and continues through summer and early fall until the first frost. Learn more about your area's hardiness zones and first/last frost dates in our blog post 'Our Experts Answer Questions, Share Resources.'

How to Sow and Plant

Sow seeds directly in the garden after the last frost, or start indoors 3-4 weeks earlier to get a head start on the growing season. Plant seeds at a depth of 1/8-1/4 inch, as they need some light to germinate. Space plants around 10 inches apart for good airflow and healthy growth. Germination typically takes 7-14 days. Choose a location that gets 6-8 hours of direct sunlight every day for the best flowering.

How to Grow

Sea Shells cosmos thrives in poor to average soil, as rich soil can lead to excessive foliage with fewer blooms. Water moderately, allowing the soil to dry between waterings to prevent weak, leggy growth. In windy areas, taller plants may need staking to prevent them from falling over. To keep the flowers blooming all season, remove spent blooms regularly. Cosmos tolerate heat and drought well, making them an excellent choice for low-maintenance summer gardens.

How to Save Seeds

  • Cosmos are insect pollinated, and there may be some crossing between varieties in the garden. You can enjoy the mixing or use caging techniques and hand pollination to avoid crossing.
  • Saving seeds from cosmos is easy: simply allow the heads to brown and dry on plants and collect seeds. Store in a cool, dry, dark place over winter.

FAQ

What makes Sea Shells cosmos different from other cosmos varieties?

This variety has unique tubular petals. This gives the blooms a fluted, seashell-like appearance, unlike the flat petals of standard cosmos.

Can Sea Shells cosmos be grown in containers?

Yes, but choose a large pot with good drainage, as cosmos have long taproots and need room to spread. This variety also grows quite tall, so the plants might need staking.

Do Sea Shells cosmos reseed themselves?

Yes, cosmos readily self-seed, meaning new plants may sprout in the same area the following year if seed heads are left to drop naturally.

Browse our full range of cosmos seeds.

Customer reviews

4.7 / 5 23 Reviews

What gardeners are saying

  • Towering plants: Often six to seven feet tall, well past the listed height.

  • Fast, easy start: Sprouts within days, direct sown or started indoors.

  • Pastel shell petals: Fluted petals in white, yellow and pinks, each plant different.

  • Pollinator favorite: Bees and butterflies flock to the blooms.

  • Growing tips: Give them space and a stake; blooms come late summer.

More to grow!
See all Cosmos Seeds