How to store cannabis seeds the right way
Storing cannabis seeds under the correct conditions allows you to preserve your favourite cannabis genetics for many years. With the right conditions you can keep the best part of your cannabis seed collection viable for a decade or more. But get the conditions wrong and the germination rates on your best-loved feminised seeds and autoflower seeds will suffer. If you are a cannabis seed connoisseur that spends time, cash and love building a collection of the best cannabis genetics then it makes sense to learn more about storing your cannabis seeds under ideal long term conditions.
Did you know cannabis seeds are living organisms?
When preserving cannabis seeds, it’s worth remembering that seeds are technically classified as living organisms. That’s 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 fine tuned to maximise seed germination rates. But provide the wrong conditions for storing cannabis seeds and your seed germination rates will decrease rapidly. Storing cannabis seeds till germination under ideal conditions is the best way to maximise germination rates.
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Key factors to watch when storing cannabis seeds
When storing cannabis seeds there are three main issues which will reduce the germination rates (or the ‘viability’) of your cannabis seeds. These are light, heat and humidity. Each of these factors will reduce the germination rates of your autoflower seeds/feminised seeds. Conversely, if you can minimise and correctly control heat, light and humidity then you will extend the lifetime of your cannabis seed collection.
Inside your cannabis seeds are delicate embryonic tissues which store the genetic code. This, in turn, defines the type of cannabis you will eventually grow. When storing cannabis seeds long term, keeping the seeds away from bright light is important - don't store them in your grow room! A sealable, light proof container is ideal.
The shell of the cannabis seed does help to protect the embryo from light. But remember, in nature, cannabis seeds were normally dropped from the plant onto the soil in autumn/fall. There they would remain under a light covering of soil until they germinated the following spring. 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 maintain maximum seed germination rates.
Dutch Passion cannabis seeds can be stored simply be re-sealing the seed packet with tape and placing it inside the seed tin or a container. Storing cannabis seeds in eppendorf tubes (black or amber) in the fridge is a popular technique. Eppendorf tubes are small plastic tubes normally used for storing liquids, but they are often used for cannabis seed storage too.
When storing cannabis seeds, humidity levels are an important factor. In order to germinate cannabis seeds, moist humid conditions are used. So it makes sense to use low humidity conditions for cannabis seed storage. You certainly don't want to store your seeds anywhere where moisture droplets, which will soften the shell. 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 suit long term seed viability. Just make sure that your seeds are stored in a dark, 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.
It’s not necessary to measure humidity levels in your fridge. Just ensure your seeds are in a sealed dry and dark container inside your fridge and they should last many years.
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.
|Humidity levels||Effects on cannabis seeds|
|75% to 100%||Humidity is too high, causing seeds to have excessively high internal moisture content which decreases long term germination viability.|
|25% to 75%||Good for cannabis seed storage, especially at low temperatures in sealed/dark containers.|
|0% to 25%||Too dry, seeds may desiccate (dry out excessively) especially if they were not in a sealed humidity proof bag/container.|
Storing cannabis seeds at low humidity levels in a dark place is a great way to maintain good germination rates. But one of the best ways for preserving cannabis seeds is to use low temperatures. 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 which slow down the cellular biochemistry. It’s the same reason that food lasts longer in the fridge than it would at room temperature.
What is the ideal storage temperature for storing seeds? Most people use temperatures of around 4ºC (39ºF). But 4ºC isn't a magic number. If you can ‘only’ store your cannabis seeds at e.g. 10ºC the seeds will last longer than they would stored at 20ºC. Storing cannabis seeds at 4ºC will allow longer seed storage than 10ºC.
Storing cannabis seeds in the freezer (-15 to -20ºC) is also possible and this allows even better seed storage. However this does come with some risks. When stored at freezer temperatures you can expect cannabis seeds to remain viable for decades. The very low temperatures effectively allow the seed embryo to survive for long periods.
Cannabis seed companies such as Dutch Passion store their archived seed collection (1970’s & 1980’s) in the freezer. This allows long term storage. However, it also comes with certain 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 home growers, the fridge (4ºC) is a great place for storing cannabis seeds.
So what are the best ways to store your cannabis seeds?
What is the optimal temperature for storing seeds? For most people, temperatures around 4ºC (in the fridge) are perfect. If the autoflower seeds/feminised seeds are in a sealed lightproof container they are automatically at a low humidity and in a dark place.
Don't worry too much about keeping your seeds in a fridge at all times. Remember that even without a fridge, a pack of seeds stored in a draw for a couple of years should still show good germination rates. Avoid storing your seeds in places with high temperatures or intense light, such as a window ledge or your grow room.
If storing cannabis seeds in a sealed plastic bag in the fridge remember that they are easy to accidentally crush if something is placed on top of them. A small box or plastic container can prevent that.
Should I date my seeds when storing them?
It’s probably not necessary for most people but it could be a useful guide for later germination.
How long can you preserve 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 weeks/months of purchase you may not need to worry too much about how to store them.
When cannabis seeds are supplied from the seed supplier, germination rates should be 90% or higher if you are buying from a proven supplier. Even after 5 years in the fridge you should still expect the majority of your cannabis seeds to germinate.
This is good news for those growers that have found the ideal cannabis seeds for their needs and want to ensure a viable seed collection of their favourite cannabis genetics for many years to come.
Drying, storing and maturing seeds from plants
Although not many growers can be bothered with the hassle of producing their own cannabis seeds, if you do attempt to produce seeds it’s important to know about maturing them.
When drying and storing and maturing cannabis seeds one of the main tips is to allow the fresh seeds time to rest before germinating. Fresh seeds haven’t had the natural time period required to allow them to reach maximum germination rates.
Typically seeds of various plants store better, and germinate faster when they have dried a little after the seeds have been collected. After a month or two in ambient conditions, the seeds have matured and should show higher germination rates.
What size mylar bags to use for storing marijuana seeds?
Size really doesn’t matter! Just ensure your seeds are sealed, safe from light/moisture and stored at low temperatures.
What if you found an old undated bag of seeds?
Whether you are preserving seeds of F1 landrace cannabis genetics or any other type of cannabis seeds your best chances of storing them is at low temperatures in dry and dark conditions. Many growers collect extensive (and expensive!) cannabis seed collections.
Dating each seed packet is a good idea, although it won't improve germination rates it will give you an idea of the age of the seeds. Even after 10 years in a fridge at 4ºC you can still expect to see a some of your seeds germinate, assuming they original seed quality was high.
If your cannabis seeds are really old, some growers may suggest a few unusual tips to increases germination. Dutch Passion can’t really recommend these techniques, they simply carry too much chance of damaging the seed. These techniques include gently sandpapering the outer layer of the seed shell, perhaps including the ridge down the side. The logic here is that particularly old/hard seed shells need assistance to open.
Dutch Passion prefer to stick to proven, established seed germination techniques that should work well for most people. The best way to germinate cannabis seeds is to do so between a couple of lightly moistened cotton pads for a couple of days.