Guide · reviewed November 14, 2026
How many seeds should you sow for a transplant target?
Distinguish germination, usable seedlings, multiple seeds per cell and rounding.
Open Seedling Batch Calculator →Start with a rate you can explain
The germination percentage is the estimated chance that an individual seed sprouts. Use a recent seed test or relevant packet information. Usable seedlings is a second estimate: among germinated cells, how many you expect to keep through transplanting. The calculator leaves both rates visible rather than hiding an optimistic assumption in a preset.
Understand the multiple-seed model
With one seed per cell, 80% germination and 90% usable seedlings, the modeled usable probability is 0.8 × 0.9 = 0.72. A target of 24 plants therefore needs 34 cells after rounding up. With two seeds per cell, the model uses 1 − 0.2² = 0.96 for at least one germination, then multiplies by 0.9. This assumes individual seed germinations are independent, which may not hold for a poor seed lot or shared growing problem.
Treat the result as an expectation
A batch with an expected 24 usable plants can still produce fewer or more. Multiple seeds may also require thinning. University of Minnesota Extension discusses sowing individually and thinning extra seedlings where appropriate. Follow the crop’s packet and growing method. This tool plans quantities; it does not predict a particular seed lot’s outcome or replace a measured germination test.