When to Plant Zinnias in Kansas
The cut-and-come-again champion. The more you cut zinnias, the more they bloom. A cottage garden essential.
The Short Answer
Kansas Frost Dates
Your planting dates depend on which part of Kansas you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern Kansas | 5b, 6a | Apr 20 - May 5 | Oct 1 - Oct 15 |
| Central Kansas | 6a, 6b | Apr 10 - Apr 25 | Oct 10 - Oct 25 |
| Southern Kansas | 6b, 7a | Apr 1 - Apr 15 | Oct 15 - Nov 1 |
Zinnias Planting Schedule for Kansas
Northern Kansas (Zones 5b, 6a)
Average last frost: Apr 20 - May 5 · Average first frost: Oct 1 - Oct 15
Central Kansas (Zones 6a, 6b)
Average last frost: Apr 10 - Apr 25 · Average first frost: Oct 10 - Oct 25
Southern Kansas (Zones 6b, 7a)
Average last frost: Apr 1 - Apr 15 · Average first frost: Oct 15 - Nov 1
Growing Zinnias in Kansas
Zinnias in Kansas's Climate
Your warm, humid summers grow zinnias prolifically. Direct sow from mid-May. Powdery mildew is the main issue in humid conditions — water at the base, never overhead, and choose mildew-resistant varieties. Cut or deadhead regularly for continuous bloom through frost.
Soil Considerations for Kansas
Prairie soils in east — rich and deep. More alkaline and thinner soils in west. Wind erosion can be an issue. Make sure soil has warmed to at least 60°F before planting zinnias outside.
Kansas Climate & Growing Season
Hot summers with strong winds. Severe thunderstorms and hail risk. Drier in the west. Good growing conditions for heat-loving crops. Zinnias 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 Kansas: Northern Kansas (5b, 6a) has a last frost around Apr 20 - May 5, while Southern Kansas (6b, 7a) sees frost end around Apr 1 - Apr 15. This difference matters for zinnias — transplant timing shifts by several weeks across the state.
Growing Tips
Water at the base to prevent powdery mildew. Cut flowers just above a leaf node to encourage more branching and blooms.
Companion Planting
Plant zinnias alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026