Species

Cosmos sulphureusSulphur Cosmos

2 other cultivars

annualN. America Native

Sulfur Cosmos

Cosmos sulphureus 'Cosmic Yellow'

The Story

Plant Bio

A half-hardy annual native to Mexico, featuring fern-like foliage and daisy-like flowers. It is exceptionally tolerant of heat, humidity, and poor, dry soils, making it easy to grow.

An All-America Selections winner, 'Cosmic Yellow' is a compact cultivar with vibrant, semi-double, golden-yellow flowers. It is known for being more floriferous and shorter than the species.

Uses & Benefits:

Cosmos sulphureus Cosmic Yellow adds vibrant yellow color to gardens and cut flower arrangements, attracting pollinators like butterflies and bees.

Its easy care and drought tolerance make it an excellent choice for low-maintenance gardens.

Provides nectar for beneficial insects, supporting local ecosystems.

SpeciesCosmos sulphureusSulphur Cosmos

Essentials

At a Glance

Plant Type

Annual

Height

18"

Width

18"

Light

Full Sun

Zones

Water

Low to Medium

Humidity

Average

Lifespan

Annual

Native To

Mexico, Central America

Toxicity

Non-toxic to humans and pets

Bloom period

Summer to Fall – Late summer

In flower about 3 months of the year

Planting

How to Grow

Tuck seeds about 1/4 inch deep into well-draining soil.
Mist seeds lightly until germination occurs, usually in 7-14 days.
Place in full sun for optimal growth and vibrant color.
Water regularly, keeping soil moist but not waterlogged.
Thin seedlings to 12-18 inches apart once established.
Deadhead spent flowers to encourage continuous blooming.

Pro Tip

Start seeds indoors 4-6 weeks before the last frost date for earlier blooms.

Keep It Thriving

Care Guide

Do

Water consistently, especially during dry spells 🌱
Deadhead to promote more flowers
Provide full sun for best color and growth
Use well-draining soil to prevent root rot

Don't

Avoid overwatering, which can cause root rot ❌
Don’t fertilize excessively as it may lead to leggy plants
Never plant in shady areas; Cosmos thrive in full sun

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Deadhead
Harvest
Pinch
Plant
Spring Cleanup

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Bright, cheerful border plantWildflower meadow accentVivid cut flower in bouquets

Companion Plants

Marigolds Zinnias Sunflowers Lavender

Multiply

Propagation Methods

Good to Know

Common Questions

Sulfur Cosmos questions

What zones can Sulfur Cosmos grow in?

Sulfur Cosmos is hardy in USDA Zone 10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Sulfur Cosmos deer resistant?

Yes — Sulfur Cosmos is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.

When does Sulfur Cosmos bloom?

Sulfur Cosmos typically blooms in summer to fall through late summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Sulfur Cosmos need full sun?

Sulfur Cosmos does best in full sun (6+ hours).

Is Sulfur Cosmos drought tolerant?

Yes — once established (usually after the first full season), Sulfur Cosmos handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.