How to Store Cannabis Seeds (and How Long They Last)
To store cannabis seeds, keep them dry, cool and dark: an airtight glass jar with a silica gel sachet, placed at the back of the fridge (4–6 °C / 39–43 °F), keeps most seeds viable for 5 years or more. In a drawer at room temperature they last 1–2 years before germination rates start to drop. This guide explains how to store seeds for the next season or for the next decade, and how to check whether old seeds are still good.
Why seeds lose viability
A seed is alive. Inside the shell an embryo waits in dormancy, slowly using up its reserves. Fresh seeds from a good breeder usually germinate at 90% or more; how fast that rate falls depends almost entirely on storage. Three things speed up ageing:
- Moisture: damp seeds "wake up" metabolically, burn their reserves and attract mould.
- Heat: every few degrees more makes the seed age faster.
- Light and air: light warms the seed, and oxygen slowly oxidises the oils in the embryo.
Control those three and seeds keep for years. Ignore them and a pack can be half dead by the following spring.
Storage options compared
| Where | Temperature | How long seeds stay good | Watch out for |
|---|---|---|---|
| Drawer or cupboard in a cool room | 15–20 °C | 1–2 years | Warm rooms, kitchens and bathrooms |
| Fridge, in a sealed jar | 4–6 °C | 5 years or more | Condensation when the jar is opened cold |
| Freezer, dried and vacuum-sealed | −18 °C | 10 years or more | Seeds that aren't fully dry can be damaged |
Short-term storage: up to one year
If you'll germinate the seeds this season or next, keep it simple. Leave them in the original breeder pack — usually a small tube or a sealed foil sachet — and put the pack in a closed box or jar, in a drawer of a cool room away from radiators, ovens and sunny windows.
- Temperature: stable and below 20 °C (68 °F).
- Humidity: low; a silica gel sachet in the box helps.
- Light: none.
Long-term storage: from one to ten years
For seeds you won't use for a while, lower both humidity and temperature, and keep them stable.
The right container
Use small glass jars with a rubber seal, or vials with a screw cap. Glass doesn't let moisture through, unlike thin plastic bags. One small jar per strain is better than one big jar: you open only what you need. Write the strain, breeder and storage date on each jar.
Silica gel
Put a small sachet of silica gel in each jar to absorb the moisture left inside. The air in the jar should stay around 20–30% relative humidity; a small humidity indicator card lets you check it at a glance. When the gel is saturated (indicator gels change colour), dry it in the oven at low heat and reuse it.
The fridge
The fridge is the best option for most home growers. Put the sealed jar at the back of a middle shelf, where the temperature is most stable, never in the door. A dedicated container also keeps it away from food.
Tip: when you take the jar out, let it reach room temperature for an hour or two before opening it. Opening a cold jar lets warm air condense on the seeds.
The freezer (only for archiving)
Freezing makes sense for rare genetics or seeds you won't touch for many years, and only if the seeds are thoroughly dry. Dry them for a week or two at room temperature in a jar with fresh silica gel, then vacuum-seal small portions so you never need to thaw the whole lot. Once frozen, take out one portion at a time and don't refreeze it.
Mistakes to avoid
- Thin zip bags as the only protection: they let moisture in over time.
- Warm spots: on top of the fridge, near the boiler, in the car.
- Opening the jar often: every time it goes in and out of the fridge, humidity can condense inside. Take what you need in one go.
- Sunlight: even a windowsill for a few weeks speeds up ageing.
- Damp places: cellars, sheds and greenhouses are among the worst spots to keep seeds.
How to test old seeds before you grow
Before planning a whole grow around old seeds, test a few. Take 3–5 seeds from the batch (or 10% of a large lot) and germinate them on a damp paper towel, as described in our guide to germinating cannabis seeds.
- 8 out of 10 or more open: storage worked, use the seeds as normal.
- 5–7 out of 10: plant a few more seeds than the plants you want.
- Fewer than 5: soak the remaining seeds for 12–24 hours before germinating and use them soon; they won't get better.
Keeping track of your collection
Once you have more than a few packs, a simple notebook or spreadsheet saves rare genetics from expiring unnoticed. For each lot write down:
- strain and breeder;
- date of purchase or harvest;
- number of seeds left;
- where it is stored (jar, shelf);
- date and result of the last germination test.
Use the oldest stock first and keep the fresh seeds in reserve.
Storing seeds you produced yourself
Seeds from your own plants must be fully ripe: hard, dark, often with stripes or a mottled pattern, and they split out of their pods easily. Pale, soft or green seeds are immature and won't keep. After harvesting, let them dry in a dark, dry place at room temperature for 2–3 weeks before putting them in a jar for the fridge.
FAQ
How long do cannabis seeds last?
At room temperature in a dark drawer, 1–2 years with good germination. In a sealed jar in the fridge, 5 years or more. Well dried and frozen, 10 years or more.
Should I store seeds in the fridge or the freezer?
The fridge, unless you are archiving seeds for many years. The freezer only pays off with fully dried, vacuum-sealed seeds that you take out one portion at a time.
Can I keep seeds in their original packaging?
Yes. Breeder packs protect from light and knocks; put them inside an airtight jar with silica gel for longer storage.
How can I tell if old seeds are still good?
Look and feel won't tell you much: the only reliable check is a small germination test on a few seeds.
Good storage turns your seeds into a reserve you can count on. When you're ready to add new strains, compare them in the seed catalogue and read our tips on buying cannabis seeds.