Seed Germination Rate Calculator
Calculate expected seedling count and germination rate from any seed packet.
Plan your planting for the seedlings you actually need.
Germination rate is the percentage of seeds that successfully sprout, and it decides how many you need to sow to end up with the plants you actually want. Sow to your target count and you will be short; sow blindly and you will spend an evening thinning a tray of two hundred lettuces.
What Affects Germination Rate?
Germination rate depends on several factors:
- Seed quality and age: Fresh seeds from reputable suppliers germinate at 80–95% for most vegetables. Seeds stored more than 2–3 years may drop to 50–60%.
- Species: Some plants germinate reliably (lettuce, beans, peas: 90%+), while others are more variable (parsley, peppers: 60–75%).
- Soil temperature: Most seeds germinate within a specific temperature range. Outside this range, germination slows dramatically or fails.
- Moisture: Seeds must absorb water (imbibition) to activate germination. Inconsistent moisture is a major cause of germination failure.
- Light/dark requirements: Some seeds need light to germinate (lettuce, basil); others prefer darkness (onions, phacelia). Most are neutral.
Typical Germination Rates by Vegetable
| Vegetable | Typical Germination % | Days to Germinate |
|---|---|---|
| Bean | 90–95% | 6–14 days |
| Pea | 85–90% | 7–14 days |
| Corn | 75–85% | 6–10 days |
| Tomato | 75–85% | 6–14 days |
| Pepper | 65–75% | 10–21 days |
| Lettuce | 90–95% | 5–10 days |
| Cucumber | 80–90% | 5–10 days |
| Carrot | 55–75% | 12–25 days |
| Parsley | 55–65% | 14–28 days |
| Onion | 70–80% | 10–20 days |
The Germination Rate Formula
Expected Seedlings = Number of Seeds × (Germination Rate / 100)
Seeds Needed for a Target Count = Target Seedlings / (Germination Rate / 100)
Improving Poor Germination
- Scarification: Scratching hard seed coats (e.g., morning glory) improves water penetration
- Soaking: Pre-soaking beans and peas overnight increases germination speed and rate
- Stratification: Cold-moist stratification breaks dormancy in many perennials and trees
- Fresh seed: Always use seeds within their recommended use-by date
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.