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 test timing | 7-day prechill then 7-14 days warm; up to 3 weeks total | As described by Oregon State seed labbeing reviewed [1] |
| TZ test | 24-48 h | [1] |
| Storage | ~5 °C, dry, sealed | Recommended to maintain germination about 6 years in [4] (secondary report)being reviewed |
| 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
- Sample randomly. Mix the whole batch, then count out 4 x 25 seeds without picking the nicest.
- 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.
- Incubate at ~24-26 °C (75-79 °F) in the dark.
- Count at day 3, day 5 and day 7 (and day 10-14 if many are slow). Remove counted seedlings.
- Classify each seed: normal seedling (healthy root, intact cotyledons emerging), abnormal (stunted, rotten root, no shoot), dead, or ungerminated firm (possibly dormant).
- Calculate germination = normal seedlings / seeds tested x 100. Report per replicate and total.
- Optional sex check for feminised batches: DNA-sex a sample of seedlings (e.g., 20-50) with validated markers [5]; one male in 50 suggests contamination worth investigating.
- 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 rate (feminised and regular) | Core product claim; a line that herms under normal conditions is not released (see diagnosing hermaphrodites) |
| Chemotype (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 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.
A seedling is a young cannabis plant from emergence of the cotyledons until it has several sets of true leaves, typically the first 2-3 weeks.Germination is the stage where a viable seed absorbs water, splits its shell and pushes out a root (radicle), usually within 1-7 days at 20-30 °C.Hemp is cannabis grown for fibre, seed or other uses and, in many laws, defined as Cannabis sativa with no more than 0.3% THC by dry weight.One of the two rounded seed leaves packed in the embryo that open first after germination and feed the seedling until the true leaves take over.Feminised seed is seed made by pollinating a female with pollen from another female (or itself) that was chemically reversed, so nearly every seed grows into a female.The share of offspring that are female; because only females lay eggs, a female-biased ratio speeds population growth.In cannabis growing, a plant (usually female) that develops both pistillate and staminate flowers or anthers; botanists call it intersex or monoecious expression.A chemotype is a plant's chemical phenotype, in cannabis usually its dominant cannabinoid class: THC-dominant (I), mixed (II), CBD-dominant (III), CBG-dominant (IV) or cannabinoid-free (V).The protective outer layer of a seed; in cannabis it is fused to the fruit wall and forms the hard shell that cracks open at germination.The dry, single-seeded fruit of cannabis that growers call a seed; a hard shell (pericarp plus seed coat) encloses one embryo and does not split open.
