Calculate germination rate, germination energy, and adjust seeding rate based on actual germination test results.
Test seed germination rate and energy, then adjust your seeding rate accordingly. Input total seeds tested, normally germinated, early germination (day 4), field area, theoretical rate, and label germination. Get actual seed rate, total seed required, and extra seed needed. Always test before planting.
You bought "certified 95% germination" alfalfa seed and planted at the standard 15 kg/ha. Emergence was patchy — only 60% ground cover. You sent a sample to the lab and got 72% germination. The seed was 3 years old and had been stored in a hot shed. You needed 20 kg/ha, not 15. The 5 kg/ha shortage cost you 30% yield in the first cutting. A $5 germination test would have saved you $200/ha in lost production.
Enter number of seeds tested and number that germinated, or enter known germination percentage. Also enter desired plant population and seed weight. Click calculate to see germination rate, viable seed percentage, adjusted seeding rate, and number of viable seeds.
The germination calculator measures seed viability and helps you adjust seeding rates based on actual germination percentage. It calculates germination rate from test results, determines how much extra seed is needed to compensate for low germination, and estimates the number of viable seeds in a given quantity.
A: Place 100 seeds (or 50 for large seeds) evenly spaced on moist paper towels or blotting paper. Roll or fold to keep seeds moist but not soaking. Place in a warm area (20-25°C for most crops). Keep moist. Count germinated seeds after 7-14 days (varies by crop: lettuce 7 days, beans 7 days, corn 7 days, peppers 14 days). Germination % = (Germinated ÷ Total tested) × 100. Repeat for accuracy.
A: Most commercial seed has 85-95% germination (minimum standards vary by crop: corn 90%, soybeans 80%, wheat 85%, vegetables 70-80%). Seed below 70% germination should be replaced or used at significantly higher rates. Germination decreases over time: store seed in cool, dry conditions (ideal: 5-10°C, 30-40% relative humidity) to maintain viability. Old seed may have lower vigor even if germination is acceptable.
A: Adjusted seeding rate = Desired population ÷ Germination rate (as decimal). Example: if you want 50,000 plants/ha and germination is 80%, seeding rate = 50,000 ÷ 0.80 = 62,500 seeds/ha. You can also account for seedling survival (typically 80-90% of germinated seeds establish): Final rate = Desired population ÷ (Germination × Survival). Always use current germination test results, not the bag label rate (which may be from testing done months ago).