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How to Store Cannabis Seeds

Cannabis seeds, when stored properly, can retain their viability for extended periods, allowing growers to plan future harvests or preserve valuable genetics. This guide explores the key factors affecting seed longevity and provides practical techniques for successful long-term storage.


How Long Do Cannabis Seeds Last in Storage



The longevity of cannabis seeds in storage depends on various factors, including storage conditions and seed quality. When stored properly in a cool, dry, and dark environment, cannabis seeds can typically last for a few months to a year before their viability starts to decline. However, if seeds are refrigerated, their lifespan can be significantly extended. With refrigeration, cannabis seeds can remain viable for up to a decade or even longer, provided they are stored in airtight containers to minimize exposure to moisture and light. By optimizing storage conditions, growers can preserve the quality and viability of their cannabis seeds for an extended period, ensuring successful germination when they are ready to cultivate.


Key Factors to Consider When Storing Cannabis Seeds



Key Factors to Consider When Storing Cannabis Seeds
Key Factors to Consider When Storing Cannabis Seeds
Key Factors to Consider When Storing Cannabis Seeds
Key Factors to Consider When Storing Cannabis Seeds

Light Exposure

While sunlight is essential for plant growth outdoors and artificial lighting aids indoor cultivation, light should be avoided when storing cannabis seeds. To keep seeds dormant, they should be stored in a dark environment with low temperatures and low humidity.

Even the light from a refrigerator bulb can potentially affect seed viability. Therefore, it’s best to store seeds in a dark place within the fridge and minimize light exposure by quickly closing the fridge door after opening. If you have a dedicated fridge for seed storage, ensure it remains closed as much as possible until you are ready to plant the seeds. Limiting light exposure is crucial for maintaining seed dormancy.

Humidity Level

Humidity is a crucial factor affecting the viability and longevity of cannabis seeds. Managing humidity levels effectively is essential to ensure the preservation and viability of cannabis seeds, particularly when considering storage for varying durations.


Relative Humidity Level Effects Storage Suitability
High Humidity (80-100%) Promotes germination; not suitable for storage Not suitable for storage
Moderate Humidity (40-60%) Increases respiration and mold risk Short-term storage only
Low Humidity (20-30%) Prevents premature germination and mold growth Suitable for short-term storage
Moderately Low Humidity (18-20%) Prevents germination and mold; maintains viability Ideal for medium-term storage
Very Low Humidity (12-14%) Prevents germination and mold; preserves viability Best for long-term storage
Extremely Low Humidity (8-9%) Risk of desiccation and potential pest issues; reduced seed longevity Not ideal; shorter longevity


  • 80 – 100% Relative Humidity

Seeds are likely to germinate at this high level of humidity. This environment is suitable for germination but not for storage, as seeds will absorb moisture and begin the sprouting process.

  • 40 – 60% Relative Humidity

Seeds increase their respiration rate, which can lead to quicker depletion of stored nutrients. Seed storage fungi also become a significant problem, potentially leading to mold growth and seed deterioration. This range is generally not ideal for long-term storage but may be suitable for short-term periods.

  • 20 – 30% Relative Humidity

Suitable for short-term storage. Seeds remain dry enough to prevent premature germination and mold growth, but this level of humidity is not low enough to ensure long-term viability.

  • 18 – 20% Relative Humidity

Optimal for medium-term storage. Seeds are kept dry enough to maintain viability over a moderate period without significant risk of germination or fungal issues.

  • 12 – 14% Relative Humidity

Best for long-term storage. Seeds at this humidity level maintain their viability for extended periods, as the low moisture content reduces metabolic activity and prevents fungal growth.

  • 8 – 9% Relative Humidity

While seeds can be stored at this level of humidity, they may have shorter longevity compared to those stored at slightly higher humidity levels. Extremely low humidity can also lead to desiccation, negatively impacting seed viability over time.

Temperature Fluctuations

Storing cannabis seeds in a dark place with low humidity helps maintain good germination rates. However, one of the most effective methods for preserving cannabis seeds is by using low temperatures. Cool temperatures significantly extend the lifespan of cannabis seeds by slowing down their cellular biochemistry, similar to how food stays fresh longer in a refrigerator than at room temperature.
Most people store their seeds at around 4ºC (39ºF). While this isn’t an absolute requirement, storing seeds at 4ºC will generally keep them viable longer than storing them at higher temperatures. For example, storing seeds at 10ºC will still be better than storing them at 20ºC, but not as effective as 4ºC.
Storing cannabis seeds in the freezer (between -15 to -20ºC) is another option and offers even better preservation. Seeds stored at these very low temperatures can remain viable for decades. However, this method carries some risks. The delicate tissues within the seed can be damaged if mishandled or shaken while frozen, potentially shattering the embryo. Therefore, freezer storage is recommended only for long-term preservation.


How to Store Cannabis Seeds Long Term


Storage Environment

To store cannabis seeds long-term, it’s crucial to provide an optimal environment. This includes keeping the seeds in a cool, dark, and dry space. Ideally, maintain a temperature range between 6-8℃ (42-46°F) to preserve seed viability. Fluctuations in temperature should be avoided, as stability is essential for maintaining seed quality over time.

Shielding from Light

Light exposure can degrade the quality of cannabis seeds, so it’s important to shield them from it. Store the seeds in opaque containers or boxes to prevent light penetration. Transparent plastic bags should be avoided for long-term storage. By keeping seeds in a dark environment, you can help preserve their genetic integrity.

Maintaining Dry Conditions

To prevent moisture buildup, it’s crucial to keep cannabis seeds in a dry environment. Excess moisture can lead to mold growth and degradation of the seeds. Consider using desiccant packs or silica gel in the storage container to absorb any humidity. Keeping the environment dry helps ensure the long-term viability of the seeds.

Refrigeration for Stability

Many people opt to store cannabis seeds in a refrigerator to maintain a stable environment. Set the refrigerator to the recommended temperature range of 6-8℃ (42-46°F) for seed storage. If possible, use a dedicated refrigerator for seed storage to minimize temperature fluctuations caused by frequent door opening. Refrigeration helps preserve seed viability over time.

Vacuum Sealing

Use vacuum-sealed bags or containers to create an airtight environment. This helps prevent oxygen exposure, which can degrade seed quality over time.

Duration and Monitoring

With proper storage conditions, cannabis seeds can maintain high germination rates for up to 5-10 years from harvest. However, it’s essential to regularly monitor stored seeds for signs of damage or degradation. Remove any compromised seeds promptly to prevent them from affecting the quality of the remaining ones. By checking seeds periodically, you can ensure their long-term viability.


What Container Should You Store Cannabis Seeds In

When storing cannabis seeds, selecting the correct container is crucial to protect them from light, moisture, and temperature fluctuations, which can affect their viability. Properly stored in appropriate containers, cannabis seeds can maintain their viability and quality for extended periods, ensuring they are ready for successful germination when needed.

  • Glass Weed Jars
    Glass jars, such as Mason jars, with airtight seals are popular for storing cannabis seeds. Glass provides excellent light protection, and the airtight seal helps maintain stable humidity levels.
  • Plastic Weed Jars
    High-quality plastic containers with tight-fitting lids can also be suitable. Opt for opaque or dark-colored plastic to shield seeds from light exposure.
  • Metal Tins
    Metal tins with secure closures offer effective protection. Ensure the interior is lined to prevent moisture buildup, which could harm seeds.
  • Cannabis Mylar Bags
    Vacuum-sealed Mylar bags create an airtight environment ideal for preserving seed freshness. Choose bags made from light-blocking materials to prevent light exposure.
  • Original Packaging
    If using original seed packets, ensure they are sealed and intact. Place them inside a larger, protective container for added security against light and moisture.

Additional Tips
Container Preparation: Ensure containers are clean, dry, and odor-free before storing seeds.
Desiccant Packs: Include desiccant packs or silica gel to absorb moisture and maintain optimal humidity levels.
Storage Environment: Store containers in a cool, dark place to further protect seeds from environmental changes.


Do Stored Seeds Need Air

Seeds do not necessarily need air while in storage, as they enter a dormant state where respiration is minimal. In fact, minimizing air exposure can help prevent moisture buildup, which is crucial for maintaining seed viability. Once seeds have been properly dried for at least a month to reduce moisture content, storing them in airtight containers helps maintain optimal conditions by preventing moisture ingress. Therefore, as long as seeds are kept dry and cold, storing them in airtight containers is ideal for preserving their viability over time.


How Do You Know When Seeds Have Gone Bad



Determining the quality of cannabis seeds involves observing several key indicators. By carefully assessing color, size and shape, sheen, age, origin, and buoyancy, you can better discern the quality of cannabis seeds and avoid planting those that may lead to disappointing results.
Watch out for cannabis seeds that exhibit a greenish hue. This coloration suggests premature harvesting by the grower or breeder, which can hinder the seeds from fully maturing. Immature seeds are less likely to germinate successfully.
Size and Shape
Poor quality cannabis seeds can vary significantly in size. However, size alone is not a reliable indicator of seed quality.
Look for seeds that are not teardrop-shaped—round on one end and tapered at the other—as these deviations from the norm may indicate genetic defects. Flat or irregularly shaped seeds often lead to germination difficulties and may produce inferior plants.
Healthy cannabis seeds typically exhibit a waxy, shiny appearance. In contrast, poor quality seeds appear dull and lack a distinct shimmer. A matte finish on a seed is often a sign of subpar quality.
Avoid using cannabis seeds that are older than one year, as age can significantly impact viability. To assess age, gently squeeze the seed between your fingers. If it feels soft, squishy, or cracks under pressure, it may not be viable for planting.
Seeds that develop unintentionally within cannabis flowers, rather than being intentionally bred by expert breeders, are generally of lower quality. Such occurrences often indicate poor cultivation practices, potentially resulting in seeds with genetic deficiencies.
Place the seeds in a glass of water to test their buoyancy. Good quality seeds typically sink within 1-2 hours of immersion. In contrast, poor quality seeds may remain floating on the water’s surface even after several hours. Persistent buoyancy is a strong indicator of seed quality issues.

Mold or mildew

Visible mold or mildew spores on the seed coat are a clear sign the seeds are unsuitable for planting.

Soft or mushy texture

Seeds should feel firm to the touch. Soft or mushy seeds might be damaged by moisture or disease.


Can I Vacuum Seal Seeds for Storage

Vacuum sealing can be a helpful technique for storing cannabis seeds. Vacuum sealing removes air, significantly reducing humidity levels within the container. This helps prevent mold growth, a major threat to seed viability.

Vacuum sealing can be a useful tool for storing cannabis seeds, especially in high-humidity environments. However, ensure proper drying and potentially use a partial vacuum to avoid crushing seeds.  For most home growers, well-sealed containers with desiccant packets in a controlled environment (fridge or freezer) might be sufficient.


Final Words

By following the recommended storage practices, cannabis growers can ensure their seeds remain viable for years to come. From understanding the detrimental effects of light, humidity, and temperature fluctuations to selecting appropriate containers and storage environments, this guide empowers growers to confidently preserve their cannabis seeds for future cultivation endeavors.


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