# Why won't my seeds germinate?

> Cannabis seeds usually fail to germinate because they are too cold, too wet, too dry or old. Fresh seed shows a taproot in 1–5 days at 22–27 °C (72–81 °F); old seed can take up to 10 days. Below about 18 °C (64 °F) germination slows sharply, and soaking longer than 24 hours or a sopping towel can drown the seed. Old seed may still sprout in 1% hydrogen peroxide.

- Canonical: https://genetixbay.com/knowledge/answers/why-wont-my-seeds-germinate.html
- Topic: Germination · Type: Troubleshooting
- Evidence: Supported · 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: Why are my seeds not germinating? | Seeds not sprouting after a week | No taproot after 5 days | My seed didn't pop, what went wrong? | Why won't my cannabis seeds crack?
- 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

[Cannabis seeds](https://genetixbay.com/knowledge/glossary/achene.md) that won't [germinate](https://genetixbay.com/knowledge/glossary/germination.md) are usually too cold, too wet, [too dry](https://genetixbay.com/knowledge/glossary/over-drying.md) or too old. Fresh seed shows a [taproot](https://genetixbay.com/knowledge/glossary/taproot.md) in 1–5 days at 22–27 °C (72–81 °F); old seed can take up to 10 days. Fix the temperature and moisture before blaming the seed. *Supported*.

## Why

Germination speed is set by temperature. [Hemp](https://genetixbay.com/knowledge/glossary/hemp.md) seed germinates across roughly 19–30 °C, with an optimum near 29.6 °C, and slows sharply on a cold windowsill [1].

A seed needs oxygen as well as water. Long soaks and [waterlogged](https://genetixbay.com/knowledge/glossary/overwatering.md) towels or plugs suffocate the embryo and favour the rot organisms that cause [damping-off](https://genetixbay.com/knowledge/glossary/damping-off.md) [4].

Seed age and storage matter. Seeds kept cold and dry at about 5 °C (41 °F) held their germination capacity for around six years; warm, humid storage costs viability far sooner [3].

Old, slow seed can sometimes be pushed. Germinating in 1% [hydrogen peroxide](https://genetixbay.com/knowledge/glossary/hydrogen-peroxide.md) in the dark gave faster, higher germination than water, including for very old seed [2].

## The numbers

| Factor | Good | Problem |
|---|---|---|
| Temperature | 22–27 °C (72–81 °F) | Below ~18 °C (64 °F): slow or stalled |
| Soak | ≤ 24 h | Over 24–36 h: oxygen starvation |
| Time to taproot | 1–5 days fresh seed | Nothing after 10 days |
| Storage | ~5 °C (41 °F), dry, airtight | Warm, humid, bright |

## What to do

1. Measure the temperature where the seeds sit, not the room. Aim for 22–27 °C.
2. Keep towels damp, not dripping; plugs moist, not wet.
3. Wait 10 days before giving up on older seed.
4. For old stock, try 1% hydrogen peroxide in a closed tube in the dark [2]. Gloves and eye protection when diluting stronger peroxide.
5. Run a 10-seed test on a batch before planting the lot.

## Common mistakes

- Germinating on a cold windowsill or floor.
- Soaking for days "until it cracks".
- Letting a paper towel dry out once the [shell](https://genetixbay.com/knowledge/glossary/seed-coat.md) has split.
- Storing seed in a warm drawer for years, then blaming the breeder.

## 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)
- [Do floating seeds mean duds?](https://genetixbay.com/knowledge/answers/do-floating-seeds-mean-duds.md) · [Do seeds need light to germinate?](https://genetixbay.com/knowledge/answers/do-seeds-need-light-to-germinate.md)
- Terms: [germination](https://genetixbay.com/knowledge/glossary/germination.md) · [radicle](https://genetixbay.com/knowledge/glossary/radicle.md)

## Follow-up questions

**How long should I wait before giving up on a seed?** Wait about 10 days before giving up on a cannabis seed. Fresh seed normally shows a taproot within 1–5 days at 22–27 °C (72–81 °F), but old or hard seed can take up to 10. If nothing has happened by then and the seed is soft, mouldy or smells sour, it has rotted. Check the temperature first, because a cold room is the most common cause of a slow start.

**Can a seed rot from too much water?** Yes. A cannabis seed needs air as well as water to germinate. Soaking it for more than 24–36 hours, or leaving it in a sopping paper towel or waterlogged plug, starves the embryo of oxygen and invites mould and damping-off organisms. Use a towel that is damp but not dripping, a medium that holds together when squeezed but does not drip, and never soak for days.

**Can I rescue old seeds that won't sprout?** Old cannabis seeds can sometimes be rescued. In a lab protocol, germinating seeds in 1% hydrogen peroxide in the dark gave faster, higher germination than plain water and helped very old, low-viability seed. Seeds stored cold and dry at about 5 °C (41 °F) keep their germination capacity for around six years, so warm storage is a common hidden cause. Wear gloves when diluting stronger peroxide.

## Sources

1. Geneve RL, et al., 2022. Temperature limits for seed germination in industrial hemp (Cannabis sativa L.). Crops 2(4):415–427. https://doi.org/10.3390/crops2040029
2. 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
3. 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
4. University of Minnesota Extension. How to prevent seedling damping off. https://extension.umn.edu/solve-problem/how-prevent-seedling-damping