# Do seeds that float mean they are duds?

> No. A cannabis seed that floats is not necessarily a dud; the float test is unreliable because it mostly measures air trapped in or on the shell, and many floaters sink within a few hours and germinate normally. The only reliable check is a germination test: 10 seeds on a damp towel at 22–26 °C (72–79 °F) in the dark for 7 days.

- Canonical: https://genetixbay.com/knowledge/answers/do-floating-seeds-mean-duds.html
- Topic: Germination · Type: Myth check
- Evidence: Myth · Status: Draft: awaiting expert review
- Full article: [Germination methods compared: soak, paper towel, plugs, direct sow](https://genetixbay.com/knowledge/germination/germination-methods.md)
- Also asked as: Does the float test work for seeds? | My seeds are floating, are they dead? | Sink or float: which seeds are good? | Should I throw away seeds that float?
- 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)"

## Short answer

No. A floating [cannabis seed](https://genetixbay.com/knowledge/glossary/achene.md) is not necessarily dead; the float test mostly measures trapped air, and many floaters sink within hours and [sprout](https://genetixbay.com/knowledge/glossary/seedling.md) normally. Judge seeds with a 7-day [germination](https://genetixbay.com/knowledge/glossary/germination.md) test instead. *Myth*.

## Why

A dry seed carries air in and around its [shell](https://genetixbay.com/knowledge/glossary/seed-coat.md). Until water gets in, that air can keep a perfectly viable seed on the surface.

Hydration, not viability, decides when it sinks. Seeds take up water over several hours, which is why a 12–24 hour soak is used to speed germination [3]. A floater on hour one often sinks by hour six.

Viability is measured by germinating seeds. Seed laboratories test [hemp](https://genetixbay.com/knowledge/glossary/hemp.md) by putting seeds in a germinator for 7–14 days and counting sprouts [4]; the simple home version is 10 seeds on a damp towel.

What really kills seeds is storage. Warm, moist storage costs germination capacity, while cold, dry storage at about 5 °C (41 °F) kept it for around six years [2]. Old, slow seed may still be pushed with a 1% [hydrogen peroxide](https://genetixbay.com/knowledge/glossary/hydrogen-peroxide.md) protocol [1].

## The numbers

| Check | Reliable? | Notes |
|---|---|---|
| Float test | No | Mostly measures trapped air |
| Colour and hardness | Rough guide | Varies by genetics |
| 10-seed towel test | Yes | 22–26 °C (72–79 °F), dark, 7 days |
| Lab germination test | Yes | 7–14 days in a germinator |
| Soak length | ≤ 24 h | Longer risks oxygen starvation |

## What to do

1. Ignore floating; plant or towel the seed anyway.
2. If a seed floats after 12 hours, tap it under gently, then move on at 24 hours.
3. For a big or old batch, run a 10-seed test first.
4. Store the rest cold, dry and airtight.

## Common mistakes

- Binning floaters from a precious pack.
- Soaking for days waiting for a seed to sink.
- Squeezing seeds to "test" them and cracking good ones.

## Related

- Full article: [Germination methods compared](https://genetixbay.com/knowledge/germination/germination-methods.md)
- [Seed viability and storage](https://genetixbay.com/knowledge/germination/seed-viability-storage.md) · [Seed germination testing](https://genetixbay.com/knowledge/breeding/seed-germination-testing-qc.md)
- [Why won't my seeds germinate?](https://genetixbay.com/knowledge/answers/why-wont-my-seeds-germinate.md)
- Terms: [seed coat](https://genetixbay.com/knowledge/glossary/seed-coat.md) · [germination](https://genetixbay.com/knowledge/glossary/germination.md)

## Follow-up questions

**How do I test if my seeds are viable?** Test cannabis seed viability with a germination test, not a float test. Place 10 seeds on a damp paper towel in a closed dish at 22–26 °C (72–79 °F) in the dark, check daily for 7 days, then count the seeds with a taproot. Eight sprouts means 80% germination. Old stock can take up to 10 days, so give it a little longer.

**Should I soak seeds before planting?** Soaking cannabis seeds before planting is optional. A 12–24 hour soak in room-temperature water speeds water uptake, and one study found soaking improved germination, but soaks longer than 24–36 hours risk starving the seed of oxygen. Never soak for days. Floating during a soak means nothing on its own: plant the seed once it has soaked or cracked.

**Do dark seeds germinate better than pale ones?** Darker cannabis seeds are usually mature and harder, but colour varies with genetics, so a pale seed is not necessarily a dud and a dark one is no guarantee. Treat colour as a rough sign of maturity only. Very pale, soft or crushed seeds are poor bets; anything firm deserves a fair germination test before you judge it.

## Sources

1. Sorokin A, Yadav NS, Gaudet D, Kovalchuk I, 2021. Development and standardization of rapid and efficient seed germination protocol for Cannabis sativa. Bio-protocol 11(1): e3875. https://doi.org/10.21769/BioProtoc.3875
2. 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
3. Physical and chemical pretreatments on germination efficiency and seedling growth of Cannabis sativa. Nativa (UFMT). https://periodicoscientificos.ufmt.br/ojs/index.php/nativa/article/view/20226
4. Oregon State University Seed Laboratory. Industrial hemp seed testing. https://seedlab.oregonstate.edu/seed-testing/industrial-hemp