Before committing an entire season's seed budget to the field, testing a small sample tells you what percentage will actually sprout — information you need both to judge whether the seed lot is worth planting and to calculate how much extra seed to buy if germination is below ideal.
Germination Rate (%) = (Seeds Germinated ÷ Total Seeds Sown in Test) × 100. This calculator then uses that rate along with your desired final plant population and field area to tell you how much seed you'll need to sow to hit your target stand.
| Germination Rate | Recommendation |
|---|---|
| 90%+ | Excellent — sow at standard rate |
| 75-89% | Usable — increase seed rate proportionally |
| 60-74% | Marginal — consider replacing seed lot |
| Below 60% | Poor — not recommended for sowing |
You sow 100 seeds from a seed lot in a germination test and count 78 sprouted after 8 days: Germination rate = 78 ÷ 100 × 100 = 78%. This falls in the "usable but increase rate" range — for a target of 10,000 plants/acre, you'd need to sow roughly 10,000 ÷ 0.78 ≈ 12,820 seeds/acre instead of the standard count, to end up with the plant population you actually want.
Testing 100 seeds gives a directly readable percentage and is the standard sample size for a quick field test. For a more statistically reliable result, testing 400 seeds split across four groups of 100 and averaging the results is the standard laboratory approach.
This varies by crop — most vegetables and cereals show germination within 5-10 days under warm, moist conditions, but always check the specific crop's typical germination window since counting too early will understate the true rate.
The most common causes are seed age (viability naturally declines over 1-3 years depending on the crop), poor storage conditions (high humidity or temperature), and mechanical damage during harvesting or handling.
It's good practice, especially if the seed has been stored for several months since certification testing, since germination can decline during storage and transport even for certified lots.