Marijuana seeds should be kept in a cool, dark place such as a basement or in your refrigerator. They should be in an air-tight container and must stay dry. Putting a cotton ball in with the seeds before storage can help suck up any extra moisture (this is why you often see little bits of cotton in seed breeder packs).
Heat and moisture ‘signal’ to cannabis seeds that it’s time to sprout, so as long as you keep the seeds in a dry, dark environment they can remain viable for years. I have heard cases of seeds sprouting after being in storage for 5 or even 10 years. However, you will notice that older seeds take longer to germinate than fresh seeds and a few of them may not sprout at all. As time goes on, fewer and fewer of the seeds will successfully germinate.
For more long-term storage, you can always refrigerate your seeds. The refrigerator will keep the seeds at a cool, constant temperature.
If you are going to go to the trouble of storing cannabis seed long-term, then you want to make sure you are storing only good seeds. After all, what would be the point in storing bad seeds? Most of the time you can tell a good quality of a cannabis seed by the way it looks.
Healthy cannabis seeds will have darker shades of gray and black on the outer shell. These darker colors can also signify genetically superior seeds.
Keeping your cannabis seeds cool and dry at a consistent temperature and humidity level is essential. First, you need to pick your storage container. It should be air-tight and keep out UV light if possible.
Effects Of Humidity On Cannabis Seeds
If you want your cannabis plants to be healthy and potent, then the seeds your start with need to be healthy and from a good strain of cannabis.
Healthy seeds should also be firm to the touch and have a glossy and wax-like look to the shell. If you roll the seed between your thumb and index finger and it feels firm, then it should be a good seed to plant and should store well in the right conditions.
Cannabis seeds store ideally at 20% to 30% humidity. If the humidity level is higher at 40% to 60% humidity, they will likely germinate. At 80% to 100% humidity, they will drown and wilt in as little as 12 hours.
How Can I Tell If Cannabis Seeds Are Good?
Storing your seeds in a cupboard or closet shelf is fine for short-term storage. Never store your seeds outside in a garage or shed because the constant temperature changes of day temps and cooler night temps will not be good for them.
If the humidity level falls below 20%, the seed may heat up and sweat, develop fungi on the outside as well as the inside. At the lowest humidity level of 10% or less, the seeds can attract insects or pests.