Annual Flower

When to Plant Cosmos in South Carolina

Delicate, daisy-like blooms that dance in the breeze. Cosmos thrive in poor soil and practically grow themselves.

The Short Answer

In South Carolina, plant cosmos based on your regional frost dates. Upstate has a last frost around Mar 25 - Apr 10, while Coastal sees frost end around Feb 25 - Mar 15. Long, hot growing season. Subtropical on coast. Two main planting seasons. Summer heat can stress cool-season crops.

South Carolina Frost Dates

Your planting dates depend on which part of South Carolina you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Upstate 7a, 7b Mar 25 - Apr 10 Oct 20 - Nov 5
Midlands 7b, 8a Mar 15 - Apr 1 Nov 1 - Nov 15
Coastal 8a, 8b, 9a Feb 25 - Mar 15 Nov 10 - Dec 1

Cosmos Planting Schedule for South Carolina

Upstate (Zones 7a, 7b)

Average last frost: Mar 25 - Apr 10 · Average first frost: Oct 20 - Nov 5

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Midlands (Zones 7b, 8a)

Average last frost: Mar 15 - Apr 1 · Average first frost: Nov 1 - Nov 15

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Coastal (Zones 8a, 8b, 9a)

Average last frost: Feb 25 - Mar 15 · Average first frost: Nov 10 - Dec 1

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Growing Cosmos in South Carolina

Cosmos in South Carolina's Climate

Cosmos love your heat and sun. Plant from March and enjoy blooms for 6+ months. They handle drought well — one of the most water-efficient flowers for warm-climate gardens. Let some flowers go to seed for naturalized volunteer displays in subsequent years.

Soil Considerations for South Carolina

Red clay in Piedmont. Sandy soils on coast. Acidic throughout. Rich alluvial soils in river valleys. Make sure soil has warmed to at least 60°F before planting cosmos outside.

South Carolina Climate & Growing Season

Long, hot growing season. Subtropical on coast. Two main planting seasons. Summer heat can stress cool-season crops. Cosmos cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.

Growing season length varies across South Carolina: Upstate (7a, 7b) has a last frost around Mar 25 - Apr 10, while Coastal (8a, 8b, 9a) sees frost end around Feb 25 - Mar 15. This difference matters for cosmos — transplant timing shifts by several weeks across the state.

Growing Tips

Don't over-fertilize — rich soil produces more leaves and fewer flowers. Let some flowers go to seed for next year's crop.

Companion Planting

Plant cosmos alongside these companions for better growth:

Tomatoes Squash

The Bottom Line

Cosmos can be grown successfully across South Carolina, but your exact planting dates depend on which region you're in. Upstate gardeners should plan around a Mar 25 - Apr 10 last frost, while those in Coastal can typically plant earlier. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Cosmos Growing Guide National planting guide with all states South Carolina Planting Calendar All plants for South Carolina Cosmos in Alabama Alabama planting dates Cosmos in Alaska Alaska planting dates Cosmos in Arizona Arizona planting dates Cosmos in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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