How long do zinnia seeds take to germinate?
Zinnia seeds sprout in 4-8 days at an optimal soil temperature of 70-75 °F. Use the planner to estimate days and a sprout date for your soil temperature.
Quick answer
Germination planner
The marker shows your soil temperature; the curve is University of Minnesota Extension (4-8 days at 70-75 F), corroborated by the Old Farmer's Almanac..
Notes & troubleshooting
A fast warm-season cut flower: 4-8 days at 70-75 F per University of Minnesota Extension. Direct-sow once soil is at least 70 F (transplants can go out once soil reaches ~60 F). Dislikes root disturbance, so direct-sowing or cells are best.
If they will not sprout
- Too cold: wait for ~70 F soil to direct-sow; cold, wet media causes rot.
- Surface-sown won't sprout: zinnia needs darkness — cover the seed.
- Transplant shock: zinnias resent disturbance; sow in cells or direct-sow.
Sources & how the planner works
The germination range (60-90 °F), optimal band (70-75 °F, best ~75 °F), 4-8 days to germinate, and 1/4 in sowing depth are taken from the sources below and last reviewed 2026-06-18.
Data basis: University of Minnesota Extension (4-8 days at 70-75 F), corroborated by the Old Farmer's Almanac.
For vegetables the planner reads Oregon State University Extension's measured days-to-seedling at the nearest tested soil temperature (the Harrington table, at 1/2 in planting depth) — it is a direct lookup of published data, not a prediction. For flowers, which have a published optimum range and days but no full temperature curve, the planner shows the cited day range within the optimum band and flags soil that is too cold or too hot. The 'sow date -> sprout window' is the sow date plus the day range. It is general guidance, not a zone-based planting calendar.
General seed-starting guidance only. Soil temperature (not air temperature) drives germination; use a soil thermometer for best results. The OSU/Harrington vegetable data assumes nighttime fluctuation to 60 F or lower and a 1/2 in planting depth. Verify timing for your specific variety and region; extension services publish local recommendations.