Cosmos Flower Seeds

Cosmos Flower Seeds

46 varieties

46 products

Learn how to plant

How to Plant Cosmos Flower Seeds

Fast Facts

Planting season
Spring
Life cycle
Annual
Sowing method
Direct Sow, Start Indoors
Seed prep
Requires Light
Light
Full Sun, Partial Shade
Water needs
Average, Low
Planting depth
1/4 inch
Spacing
12 inches, 18 inches, 9 to 12 inches
Mature height
Varies by variety
Hardiness zones
2 to 10
Bloom season
Summer, Summer through Fall
Days to maturity
60 to 90 days, 75 to 90 days, 90 to 100 days

Ranges cover every variety in this group. Check the product page for the exact figures.

About Cosmos Flower Seeds

Cosmos Flower Seeds grow in full sun, partial shade positions. Flowering runs summer or summer through fall. The figures below are the ones on the packets in this group; each product page carries the exact numbers for that variety.

When to plant

Plant in spring. Seed can be started indoors ahead of the season or sown straight into prepared ground once it has warmed. Hardy in zones 2 to 10 — your local frost dates decide the exact week.

Where to plant

Choose a site in full sun, partial shade. Water needs are average, low once the plants are established. Free-draining soil matters more than rich soil; seed sown into ground that stays wet rots before it germinates.

How to plant

Sow 1/4 inch deep. This seed needs light to germinate, so press it onto the surface and firm it in rather than burying it. Water gently to settle the soil, then keep the surface evenly moist until seedlings or shoots appear. Indoor starts do best in warmth and bright light; harden the seedlings off over a week before planting out.

How to care

Keep watering average, low, at the base of the plant rather than over the leaves. Grown as an annual, so plan to sow again next season. Flowers appear summer or summer through fall; cutting or deadheading regularly keeps more coming.

Find your growing zone All planting guides