Seed Storage Guide
Quality cannabis seeds stored properly can remain viable for 5–10 years or longer. Stored poorly, they can fail to germinate in months. The enemies are simple: heat, light, humidity, and oxygen.
The Four Enemies of Seed Viability
Heat accelerates metabolic activity within the seed, depleting its stored energy reserves. Store above 25°C consistently and germination rates drop significantly within a year. Light triggers metabolic activity and can damage the embryo — always store in opaque containers or dark locations. Humidity above 8–10% triggers premature germination attempts and promotes mold growth on seed surfaces. Below 5%, seeds can desiccate. The ideal range is 5–8% relative humidity. Oxygen drives oxidative degradation of seed oils and genetic material. Reducing oxygen exposure (vacuum sealing, oxygen absorbers) significantly extends viable life. Temperature fluctuations are particularly damaging — condensation from temperature changes introduces moisture.
Short-Term Storage (Under 6 Months)
For seeds you plan to use within a growing season: a cool, dark drawer or cabinet is sufficient. Keep seeds in their original breeder packaging (typically sealed envelopes or vials) or transfer to opaque film canisters or small glass jars. Add a small desiccant packet (silica gel) to control humidity. Keep away from temperature extremes — avoid areas near radiators, ovens, or in direct sunlight. Room temperature (18–22°C) with low humidity and darkness will maintain viability well for 6–12 months with minimal degradation.
Long-Term Storage (1–10 Years)
For long-term preservation of genetics: use the refrigerator (3–8°C) or freezer (-18°C to -20°C) with proper preparation. Refrigerator: Place seeds in an airtight glass jar with desiccant packets, wrap jar in black tape or aluminum foil, store in the back (most stable temperature). Do not open frequently — condensation from temperature changes damages seeds. Freezer: For multi-year storage (5–10+ years), freezing is optimal. Seeds must be completely dry before freezing (6–8% RH) — freeze-thaw cycles with moisture cause ice crystal damage. Vacuum-sealed packets with oxygen absorbers inside an airtight jar provide near-optimal preservation. Bring seeds to room temperature before opening to prevent condensation.
Testing Viability Before Planting
Before planting stored seeds, a simple float test provides a rough viability check: place seeds in room-temperature water for 1–2 hours. Seeds that sink are generally viable (denser, with intact embryos); seeds that float may have damaged or absent embryos — though this is not definitive, and many float-test failures still germinate successfully. A more reliable test: attempt to germinate 2–3 seeds before committing to a full grow. Germination rates below 50% after 7 days suggest compromised viability. Visual inspection: healthy seeds are dark (tan, brown, gray, or mottled), hard, and symmetrical. Pale, green, or white seeds are immature; cracked or very soft seeds are likely damaged.
- ✓Under 6 months: cool dark drawer + desiccant
- ✓6–24 months: sealed jar in refrigerator (3–8°C)
- ✓2–10 years: vacuum-sealed, freezer (-18°C)
- ✓Ideal humidity: 5–8% RH
- ✓Always use desiccant packets
- ✓Never freeze wet seeds — ice crystals kill embryo
- ✓Bring frozen seeds to room temp before opening