You've just came into more seeds than you can grow - it easily happens. Cannabis seed collecting can become an addiction. So you better know how to store those seeds so you can pop them at some time down the road.
Cannabis seeds are living!
Seeds of all sorts are classified as living organisms because they have an embryo which is capable of being germinated and growing into a new plant. Just like any other seed, environmental conditions for storing cannabis seeds can be optimized in order to produce good seed germination rates. Wrong conditions for storing your seed and germination rates will decrease in a quick hurry.
Things you need to consider
Light, humidity, and heat. These 3 things will make or break the germination rates of your stored seeds.
Light
When storing cannabis seeds long term, keep those babies away from bright light. The shell of the cannabis seed does help to protect the embryo from light. Cannabis seeds were never designed to cope with intense light levels. Storing cannabis seeds in the fridge, in a dark humidity proof container is a good way to keep them happy.
Humidity
Humidity is your enemy! When we want our seeds to germinate, we keep them moist, and in a humid environment. When we want to store our seeds we want to keep them dry. Water/moisture is a very effective way to soften the hard, rigid shell of the cannabis seed. This allows the tap root to emerge.
When storing cannabis seeds for the long term, the actual water content inside the seed will be around 10%. Storing cannabis seeds in the refrigerator is an easy way to maintain the low humidity levels that allow us to store seeds for long period of time. A dark and dry container without any condensation near the seeds and you should be able to store cannabis seeds in the fridge for perhaps 5 years or more and still have good germination rates.
If you have produced your own cannabis seeds you may be aware that when they are very fresh, straight off the plant, they may even be a little too fresh to germinate. That’s why some believe in storing and maturing cannabis seeds for a short period at room temperature. This allows moisture content of the seed to drop enough for the seeds to become more viable. How long to let seeds dry before storing? A couple of months at room temperature should be sufficient.
Temperature fluctuations
You got the light and the humidity down... now let's talk temp. Cutting right to it - low is the way to go. At low temperatures cannabis seed life is greatly extended. This is because the delicate living plant tissue inside the seed can survive for much longer periods at cool temperatures. Those cool temps slow down the cellular biochemistry of the seed. That all means, it stays viable for a much longer period of time compared to higher temperatures. Kind of like food - that steak will last longer in the fridge, and even longer in the freezer than if you left it laying out on the counter.
What the best temps then? Most people use temperatures of around 38ºF. That's not some magic number - its fridge temp - or there abouts. Cannabis seeds stored at 50ºF will last longer than they would stored at 70ºF. Storing cannabis seeds at 38ºF will allow longer seed storage than 50ºF. Storing cannabis seeds in the freezer (5ºF to -5ºF) is also possible and this allows even better and longer seed storage. When stored at freezer temperatures your seeds will remain viable for decades. However, it also comes with some risks. In the freezer, the delicate frozen tissues in the seed embryo can shatter if the seeds are mishandled or shaken. That’s why the freezer is only recommended for those placing seeds into very long term storage. For most folks the fridge is a great place for storing cannabis seeds. Obviously, if you accumulate a big library of seeds, you would probably want to consider freezer storage.
How long can I keep my cannabis seeds?
In the freezer you can store cannabis seeds for decades. In the fridge, you should see good germination rates (50% or more) even after 5+ years. Without using the fridge, germination rates start to decrease earlier and faster.
If you usually germinate your cannabis seeds within a few months of purchase you may not need to worry too much about how to store them.