Germination Rate Test

A germination rate test shows what percentage of a seed lot is still capable of producing normal seedlings under suitable conditions. It is useful for older seed, home-saved seed, uncertain storage history, and packets that produced uneven stands in the past. A simple test can prevent wasted tray space and help you adjust sowing rates before planting a large crop.

Know What the Test Measures

The basic result is the percentage of tested seeds that produce usable seedlings.

Use a Representative Sample

Select seed from different parts of the packet or container rather than choosing only the largest or best-looking pieces.

Use More Seeds When Possible

Larger sample sizes give a more stable estimate of the whole seed lot.

Use Smaller Samples for Rare Seed

If seed is scarce, test fewer seeds and interpret the result with more caution.

Count the Seeds Before Starting

You need the original number tested to calculate a percentage later.

Label the Test Clearly

Record crop, variety, harvest or purchase year, and test date.

Test One Seed Lot at a Time

Do not mix old and new seed or several varieties into a single test.

Use a Suitable Germination Method

Paper towels, coffee filters, seed trays, or other clean moist media can work depending on the crop.

Use a Clean Container

Clean materials reduce the chance that mold or residue interferes with the test.

Moisten the Medium Evenly

The test material should be moist enough for seed to absorb water without leaving seeds submerged.

Do Not Saturate the Test

Excess water can reduce oxygen and encourage rot.

Keep Seeds Separated

Spacing makes roots easier to observe and reduces confusion when counting.

Use Crop-Appropriate Temperature

Seeds tested too cold or too warm may appear weak even when the lot is still viable.

Use Crop-Specific Light Conditions

Some seeds have particular light or darkness requirements during germination.

Keep Moisture Consistent

Drying out during the test can produce a falsely low result.

Avoid Excess Condensation

Constant dripping moisture can promote mold and oxygen problems.

Check the Test Regularly

Observe emergence and seed condition without disturbing roots unnecessarily.

Record the First Germination

The first sprout provides useful information about speed as well as final percentage.

Count Normal Seedlings

For practical garden use, focus on seedlings that emerge and appear capable of continued normal growth.

Note Abnormal Seedlings

Malformed or extremely weak seedlings can indicate aging seed or other problems.

Record Moldy or Rotten Seeds

Seed that decays during the test provides useful information even if it never germinates.

Use a Reasonable End Point

Different crops germinate at different speeds, so use crop-specific expectations rather than ending every test on the same day.

Do Not Stop Too Early

Older seed may germinate more slowly than fresh seed.

Do Not Wait Indefinitely

A test should eventually be closed once the crop's normal germination window has clearly passed.

Calculate the Percentage

Divide the number of normal seedlings by the number of seeds originally tested, then multiply by one hundred.

Example With Ten Seeds

If eight of ten seeds produce normal seedlings, the measured germination rate is eighty percent.

Example With Twenty Seeds

If fifteen of twenty seeds produce normal seedlings, the measured germination rate is seventy-five percent.

Remember That Small Samples Swing Easily

With ten seeds, one seed changes the result by ten percentage points.

Repeat Questionable Tests

If temperature, moisture, or cleanliness was poor, repeat the test before judging the entire seed lot.

Compare Old and New Seed

Testing both under identical conditions can show whether storage age is responsible for poor performance.

Use Results to Adjust Sowing Rate

A moderately reduced germination rate does not always mean seed must be discarded; sowing more heavily may compensate.

Discard Severely Failed Lots When Practical

If repeated good tests show extremely poor germination, replacement seed may save time and space.

Track Germination Speed Too

Slow emergence can matter even when final percentage is acceptable.

Record Storage Conditions

Heat, humidity, and frequent container opening may explain why one lot deteriorated faster than another.

Keep Test Results With the Seed Lot

Write the percentage and date on the packet, label, or inventory record.

Retest Older Seed Periodically

Seed viability declines over time at different rates depending on crop and storage conditions.

Do Not Compare Unrelated Crops Directly

Different species have different natural germination speeds and storage lives.

Use Controlled Tests for Viability Questions

A controlled indoor test helps separate seed quality from outdoor weather, pests, and soil crusting.

Practical Takeaway

Test a representative labeled sample under suitable moisture, temperature, and light conditions, count normal seedlings at an appropriate end point, calculate the percentage, and use the result to decide whether to sow normally, sow more heavily, retest, or replace the seed.