About SeedCheck

A seed germination viability calculator for home gardeners.

How It Works

SeedCheck estimates the germination probability of your seeds based on a deterministic formula:

  1. Age calculation:The age of your seeds (years since purchase) is compared to the crop's baseline viability years.
  2. Storage adjustment: A piecewise-linear modifier based on temperature, humidity, and light conditions adjusts the baseline probability. Ideal storage (cool, dry, dark) = 1.0 multiplier; poor storage = as low as 0.3.
  3. Germination rate:The adjusted probability is multiplied by the crop's expected fresh-seed germination rate to get the final percentage.
  4. Health classification:Green (≥70%), Yellow (40-69%), Red (<40%).

Data Sources

The viability lookup table is curated from the following sources:

  • USDA Extension Publication G6151 (Missouri Extension)
  • Oregon State University Extension Service
  • Cornell University Department of Horticulture
  • Seed Savers Exchange viability guidelines

Storage-condition modifiers are based on USDA qualitative guidance and use a single generic curve applied to all crops. This is an honest approximation — per-crop curves are not available in published research.

Storage Modifier Details

Temperature

4-10°C → 1.0 (ideal) · 10-21°C → 1.0→0.8 · 21-27°C → 0.8→0.6 · >27°C → 0.5

Humidity

≤40% → 1.0 · 40-60% → 1.0→0.85 · 60-75% → 0.85→0.6 · >75% → 0.4

Light

Dark → 1.0 · Dim → 0.9 · Bright → 0.6

Disclaimer

SeedCheck provides estimates based on published USDA extension data and generalized storage-condition curves. Actual germination depends on many factors beyond the scope of this calculator, including seed variety, seed quality at purchase, disease, soil conditions, and weather. Always use the paper-towel test to verify viability before planting. Results are for informational purposes only.

Privacy

SeedCheck is a client-side-only application. All seed data is stored in your browser's localStorage. No data is sent to any server. You can export your seed list as CSV at any time for backup.