# Seed germination testing and quality control for breeders

> Before seed leaves your hands, test it: germinate a random sample of at least 100 seeds (400 in four replicates is the lab standard) and count normal seedlings, not just cracked seeds. Report the result with the date on the batch record. Store seed cool and dry; one study recommended about 5 °C to keep germination for years.

- Canonical: https://genetixbay.com/knowledge/breeding/seed-germination-testing-qc.html
- Category: Breeding · Level: Breeder
- Evidence: Supported · Status: Draft: awaiting expert review (some figures are being checked)
- Stage: Seedling · Systems: Any system
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Questions and answers

**How do I test [cannabis seed](https://genetixbay.com/knowledge/glossary/achene.md) [germination](https://genetixbay.com/knowledge/glossary/germination.md) rate?** Test cannabis seed germination by randomly counting out 4 x 25 seeds from the mixed batch, placing each replicate on two layers of moist paper towel with distilled water in a closed container, and incubating at about 24-26 °C (75-79 °F) in the dark. Count normal [seedlings](https://genetixbay.com/knowledge/glossary/seedling.md) at days 3, 5 and 7, then report the percentage, date and sample size.

**What is a good germination rate for cannabis seeds?** A good germination rate for fresh, well-made cannabis seed is 85-90% or higher, a grower practice target. Count only normal seedlings with a healthy root and intact [cotyledons](https://genetixbay.com/knowledge/glossary/cotyledon.md); a seed that cracks but produces a stunted or deformed seedling doesn't count. Always publish the rate with the test date and the number of seeds tested.

**How many seeds should I test?** Test at least 100 cannabis seeds per batch, as 4 replicates of 25, the GenetixBay suggested minimum; official seed labs test 400. For batches under 200 seeds, test at least 10% or 20 seeds and state the number. Small tests are rough: at a 90% rate, 20 seeds gives about plus or minus 13 points, 100 seeds about 6.

**How should I store cannabis seeds?** Store cannabis seeds cool, dry, dark and sealed, at about 5 °C. Dry them at room conditions for about a week before sealing so moisture stays low, and keep them in a sealed container, because a fridge without one exposes seeds to moisture cycles. Avoid warm drawers, and re-test germination every 12 months.

**How long do cannabis seeds stay viable?** Cannabis seeds stored dry and sealed at about 5 °C were reported to maintain germination for roughly 6 years, though that figure comes from a secondary report. Germination falls over time, faster in warm or humid storage, so re-test stored batches every 12 months and regenerate seed before germination drops too far.

**What is a tetrazolium test?** A tetrazolium (TZ) test is a quick seed viability test that stains living seed tissue red, usually within 24-48 hours. It estimates the percentage of seeds that are alive, which can be higher than the germination rate because some living seeds are dormant or weak. A germination test remains the measure of normal seedlings.

**Short answer.** Count normal seedlings from a random sample, under controlled conditions, and report the percentage with the test date and sample size. Official labs test 400 seeds in replicates [2][3]; a small breeder should test at least 100 per batch (or 4 x 25). A seed that cracks but makes a deformed or weak seedling is not "germinated" for QC purposes.

## What's happening

**Germination** (in seed-testing terms) is the percentage of seeds that produce normal seedlings under favourable conditions [1]. **Viability** is the percentage alive, which can be estimated quickly with a tetrazolium (TZ) stain that turns living tissue red, typically in 24-48 hours [1]. Germination ≤ viability, because some living seeds are dormant or weak.

## Numbers that matter

| Item | Standard or target | Notes |
|---|---|---|
| Official test size | 400 seeds, in replicates | AOSA practice reported by state labs [2][3] |
| Breeder in-house test | ≥100 seeds (4 x 25) per batch | GenetixBay suggested minimum |
| Small batch (<200 seeds) | Test ≥10% or 20 seeds, state the n | Smaller tests are wide-error estimates |
| Official [hemp](https://genetixbay.com/knowledge/glossary/hemp.md) test timing | 7-day prechill then 7-14 days warm; up to 3 weeks total | As described by Oregon State seed lab [1] |
| TZ test | 24-48 h | [1] |
| Storage | ~5 °C, dry, sealed | Recommended to maintain germination about 6 years in [4] (secondary report) |
| Seed moisture | Low; dry seeds at room conditions for a week before sealing | *Grower practice* |
| Good fresh germination | ≥85-90% | *Grower practice* target for well-made seed |

## Error bars for small tests

A germination percentage from a small sample is rough. Approximate 95% margin of error for an observed 90% rate [6]:

| Seeds tested | ±margin (approx.) |
|---|---|
| 20 | ±13 points |
| 50 | ±8 points |
| 100 | ±6 points |
| 400 | ±3 points |

(Normal approximation, 1.96 x √(p(1-p)/n); less accurate at very small n.)

## Step by step: an in-house test

1. **Sample randomly.** Mix the whole batch, then count out 4 x 25 seeds without picking the nicest.
2. **Set up.** Two layers of moist paper towel (or germination paper) in a closed container, one replicate each. Use distilled water. Label each with batch ID and date.
3. **Incubate** at ~24-26 °C (75-79 °F) in the dark.
4. **Count at day 3, day 5 and day 7** (and day 10-14 if many are slow). Remove counted seedlings.
5. **Classify** each seed: normal seedling (healthy root, intact cotyledons emerging), abnormal (stunted, rotten root, no shoot), dead, or ungerminated firm (possibly dormant).
6. **Calculate** germination = normal seedlings / seeds tested x 100. Report per replicate and total.
7. **Optional sex check** for [feminised](https://genetixbay.com/knowledge/glossary/feminised-seed.md) batches: DNA-sex a sample of seedlings (e.g., 20-50) with validated markers [5]; one male in 50 suggests contamination worth investigating.
8. **Record** the result on the GB-BAT with date, method, n and the person who ran it.

## Quality control beyond germination

| Check | Why |
|---|---|
| Seed count per pack (count, not weigh) | Customer trust |
| Visual: cracked, immature (pale), insect damage | Removes poor seed before packing |
| Off-type rate in a grow-out | Shows whether the line is what you say |
| Sex ratio (regular) / male or [intersex](https://genetixbay.com/knowledge/glossary/hermaphrodite.md) rate (feminised and regular) | Core product claim; a line that herms under normal conditions is not released (see [diagnosing hermaphrodites](https://genetixbay.com/knowledge/diagnosis/hermaphrodites.md)) |
| [Chemotype](https://genetixbay.com/knowledge/glossary/chemotype.md) (where claimed) | Legal and customer claim |
| Re-test after storage (every 12 months) | Germination falls over time |

## Common mistakes

- Testing the 10 best-looking seeds.
- Counting a cracked [shell](https://genetixbay.com/knowledge/glossary/seed-coat.md) as germination.
- Storing seed in a warm drawer, or in a fridge without a sealed container (moisture cycles).
- Publishing a germination rate with no date or sample size.

## Evidence

- Germination and TZ definitions, lab sample sizes: *Established* (seed-testing standards) [1][2][3].
- Cool, dry storage of Cannabis seed: *Supported* [4].
- In-house sample sizes and thresholds: *Grower practice* / GenetixBay practice.

## Sources

1. Oregon State University Seed Laboratory. Industrial hemp seed testing. https://seedlab.oregonstate.edu/seed-testing/industrial-hemp
2. Minnesota Department of Agriculture. Cannabis seed testing. https://www.mda.state.mn.us/cannabis-seed-testing
3. Alaska Plant Materials Center, State Seed Laboratory. Seed testing. https://plants.alaska.gov/SeedTest.html
4. Small E, Brookes B. 2012. Temperature and moisture content for storage maintenance of germination capacity of seeds of industrial hemp, marijuana, and ditchweed forms of Cannabis sativa. Journal of Natural Fibers 9(4):240-255. https://doi.org/10.1080/15440478.2012.737179
5. Toth JA, Stack GM, Cala AR, et al. 2020. Development and validation of genetic markers for sex and cannabinoid chemotype in Cannabis sativa L. GCB Bioenergy 12(3):213-222. https://doi.org/10.1111/gcbb.12667
6. Suza W, Lamkey K (eds). 2023. Quantitative Methods for Plant Breeding. Iowa State University Digital Press. https://iastate.pressbooks.pub/quantitativeplantbreeding/