When to Plant Cosmos in Louisiana
Delicate, daisy-like blooms that dance in the breeze. Cosmos thrive in poor soil and practically grow themselves.
The Short Answer
Louisiana Frost Dates
Your planting dates depend on which part of Louisiana you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern Louisiana | 8a, 8b | Mar 1 - Mar 15 | Nov 10 - Nov 25 |
| Southern Louisiana | 9a, 9b | Feb 1 - Feb 20 | Dec 1 - Dec 20 |
Cosmos Planting Schedule for Louisiana
Northern Louisiana (Zones 8a, 8b)
Average last frost: Mar 1 - Mar 15 · Average first frost: Nov 10 - Nov 25
Southern Louisiana (Zones 9a, 9b)
Average last frost: Feb 1 - Feb 20 · Average first frost: Dec 1 - Dec 20
Growing Cosmos in Louisiana
Cosmos in Louisiana'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 Louisiana
Rich alluvial soils in river valleys. Heavy clay in many areas. Acidic throughout. Sandy in some coastal areas. Make sure soil has warmed to at least 60°F before planting cosmos outside.
Louisiana Climate & Growing Season
Subtropical. Long growing season. Very hot and humid summers — some crops need shade. Year-round gardening possible. 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 Louisiana: Northern Louisiana (8a, 8b) has a last frost around Mar 1 - Mar 15, while Southern Louisiana (9a, 9b) sees frost end around Feb 1 - Feb 20. 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:
The Bottom Line
Last reviewed: March 29, 2026