What to check first
Read the crop's requirements first
Use the packet or species-specific Extension guidance for temperature, light and expected time. Many vegetables suit a simple warm-paper test, while some flowers need chilling or another dormancy treatment. No sprouts under the wrong conditions do not prove all the seed is dead. [3] [2]
Choose a representative sample
Take seeds randomly rather than selecting only the plumpest. Iowa recommends at least 20 when available, with larger samples giving more information; Illinois demonstrates a ten-seed test. If only a few seeds remain, recognize that testing uses some of a limited supply. [1] [2]
Set up a labeled, moist test
Dampen paper towels, spread the seeds so they remain separate, and fold or roll the paper. Put it in a bag or covered container to limit drying. Label the crop, variety, seed year, test date and number used. [1] [2]
Choose the next step for your plant
Check regularly without ending too soon
Keep the paper damp, without submerging the seeds. Inspect every day or two once germination is expected, recording sprouts as they appear. Allow the crop's normal interval before judging slow seeds, and check temperature or dormancy needs if nothing happens. [2] [3]
Calculate and use the result
If 16 of 20 seeds sprout, the observed rate is 80 percent. Record that as a sample result. You might sow extra where thinning is easy, or replace weak seed when space and timing are tight; compare with the packet's original germination information. [1]
What to avoid
- Do not call a ten-seed test a precise prediction: one additional sprout changes its result by ten percentage points.
- Do not use one universal seven-day deadline or pass percentage for every vegetable, flower and native seed.
What to watch next
If the first test gives an unexpected result, check the setup and repeat with another sample when enough seed remains. Watch the seedlings as well as counting initial sprouts; old seed can sprout but produce weak plants. Use fresh seed when uncertainty would jeopardize a time-sensitive planting.
Common questions
Does a 50 percent result mean I must discard it?
Not automatically. Extension guides offer different practical thresholds. Replacement may save space and effort, but scarce seed may still be worth growing with realistic expectations. Correct conditions and the value of the seed matter alongside the percentage. [1] [2]
Can I plant the sprouted test seeds?
Sometimes, if the planting time and conditions are suitable. Handle them gently and avoid damaging the new root. Do not count on salvaging every tested seed when deciding how large a sample you can afford. [1]
Sources and review
This guide was prepared with AI assistance and checked against the sources below. It has not been reviewed by a botanist. Conditions and plant responses vary; use the checks above to decide what applies. Read our editorial standards.
- Iowa State University Extension: How to store seeds and test germination rates
Random counted samples, damp paper tests, germination calculation and dry sealed storage.
- University of Illinois Extension: Are my seeds still good? Testing seed germination
Small-sample germination tests, packet timing, dormancy exceptions and declining seed quality.
- NC State Extension: Extension Gardener Handbook, Chapter 13 — Propagation
Species-specific germination and dormancy; softwood/hardwood growth stages and draining rooting media.