Testing seed germination rate reveals if it will produce a successful crop.
The basic paper towel test
- Moisten a paper towel with a spray bottle. Set the damp towel on a plate.
- Place at least 10 seeds on towel, ½” apart.
- Top with a second damp paper towel.
- Cover the plate with loose plastic wrap.
- Annotate variety, date and time.
- Keep plate in a warm (70-80 degree F) place. Moisten paper towels with additional water if they start to dry out. Check seeds daily until the majority of seeds have germinated. 2-20 days depending on vegetable variety.
- After 20 days, calculate germination rate. 8 out of 10 seeds in an 80% germination rate.
The soil test
Some seeds just don’t germinate well in paper towels. For these, plant the seeds in a tray of wet potting soil. Keep the soil evenly moist and warm until you have concluded that all the viable seeds have germinated. Each time you count the germinated seeds, clip their sprouts near ground level. The bigger the little plants get, the more water they will use from the soil each day; if they get too big, the soil will dry out much more quickly. Clipping sprouts also ensures that you won’t get a confusing tangle of growth.
A low germination rate indicates poor seed quality. You may choose to plant your seed at greater density to make up for germination shortfalls.