How to Properly Store and Preserve Cannabis Seeds [Explained]
If you don’t begin with great seeds, you can forget about producing a harvest of high-quality marijuana. A lot of growers seem to forget one simple fact: Your seeds are alive! Although cannabis seeds are fairly durable, improper storage can ruin them. If you’re paying $10-$20 a seed, losing a full batch is an expensive mistake.
Before your marijuana seeds germinate, they are in a similar state to animals when they hibernate. Like all living organisms, your seeds can die if you don’t take care of them correctly. The good news is that cannabis seeds can last for five years after harvest with proper storage.
In this guide, we outline how to store and preserve your cannabis seeds. We focus on the following:
- Insects & Pests
- Germinating old seeds
Keeping Light Away from Your Marijuana Seeds
You must keep your seeds in a location that is cool, dark, and dry. It is best if you keep the seeds in their original packaging. When they are exposed to temperature changes or light, cannabis seeds begin using their store of nutrients. This is a disaster because they ultimately won’t have the nutrients to germinate.
When they are exposed to temperature changes or light, cannabis seeds begin using their store of nutrients.
Make sure your seeds remain away from light, as it can directly trigger germination.
What’s the Right Storage Temperature?
The best temperature to store your cannabis seeds at is between 43- and 47-degrees Fahrenheit. The lower the temperature, the less likely your seed is to germinate unexpectedly. Experienced growers tend to have special refrigerators to store their seeds. Ideally, your fridge is a no-frost model. If you can place the seeds in the fruit and vegetable section, that is even better.
Another option is to freeze the cannabis seeds. If you go down this route, please ensure that you vacuum pack them first. Then put them in a dark container. Also, it would help if you germinated these seeds immediately once they come out of the freezer. Don’t allow them to thaw first.
What About Humidity?
Here is a quick overview of what will likely happen to cannabis seeds at different humidity levels:
Your cannabis seeds need a certain level of moisture for germination. If the humidity level gets too high, your seeds will rot in storage. An extremely low level of humidity of around 8-10% is suitable only for long-term storage. If it drops below 8%, you offer any insects present in the seeds the chance to become active and start reproducing.
The Right Storage Options for Your Cannabis Seeds
You now understand that you must store the seeds away from direct light. We have also outlined the need for relatively low humidity and a refrigerator-level temperature. Different options are available depending on how long you intend to store the seeds.
If you only require short-term storage, a dark drawer or cupboard is sufficient. The most important thing, regardless of the duration of storage, is to avoid temperature and humidity fluctuations. Rapid variations in temperature, in particular, can destroy your seeds. If you live in a location with warm daytime temperatures and cold nights, avoid outside storage.
For short-term storage, place the seeds in a container with desiccant. Seal it, and place it in a cool, dark place.
Once you enter medium-term storage (a few months), it is time to use an airtight container. Examples include a mason jar or Ziploc bag. Place this sealed container in the fridge. Remember that opening your fridge can cause significant temperature fluctuations. As a result, it is ideal if you have a second fridge that is seldom used.
Also, you should note that modern fridges have low humidity levels. If the humidity is too low, your seeds will begin using up nutrients.
If you want to store your seeds for at least six months, use a vacuum-sealed container. You can achieve this effect by removing all the air from a Ziploc bag. There are also special vacuum-sealed containers available online. Put the sealed bag in a dark container and put it in the fridge.
You also have the option of placing the seeds in the freezer. Remember, though; you need to germinate them immediately upon removal.
A Note on Insects & Pests
Imagine paying $100+ for seeds, going to the trouble of storing them, only to find that insects ruin them. Unfortunately, all you need is one insect in a container to destroy all of your seeds. The first consideration is to avoid exposure to ultra-low humidity. However, for long-term storage, this is precisely what you are supposed to do!
One option is to spread diatomaceous earth (D.E) where you store them. This is a type of sand that has a fossilized algae base. Crucially, for our purposes, it serves as an excellent natural insecticide. Unfortunately, you shouldn’t use D.E if you plan to store your seeds in a fridge with other food.
Imagine paying $100+ for seeds, going to the trouble of storing them, only to find that insects ruin them.
It would help if you also stored your seeds as high above the ground as possible. This reduces the possibility of a pest like a rodent coming in and feasting on the seeds.
Insects and pests also thrive in dirty storage areas. As a result, you must ensure the storage area remains clean. Otherwise, you won’t just attract pests to your seeds; microbes will form and damage the seeds. Do you want to consume marijuana from contaminated seeds?
You can ‘test’ your seeds once you have removed them from storage. Place them in water. If they sink, they should be fine. However, if they float, it is more likely that they are bad seeds. You can still try to germinate, but there is a greater risk of producing poor-quality cannabis, or else the seeds fail to sprout. You can keep floaters in water for approximately 72 hours to see if they sprout a tail.
If you have old seeds not stored in ideal conditions, there are still a few ways to germinate them.
- Remove the hard ridge with a sharp knife.
- Soak the seeds in carbonated water with germination booster, fulvic acid, or hydrogen peroxide. Use room temperature water, and perform this pre-soak for at least 12 hours in a dark area.
- Scratch the tough outer shell with sandpaper. Believe it or not, this process could help warmth and moisture get inside. This process is called ‘scarring’ and should happen before you soak the seeds.
- Make a small cut into the shell as a last-ditch attempt to get it to sprout.
Final Thoughts on Storing and Preserving Cannabis Seeds
If you purchase marijuana seeds and intend to use them almost immediately, you should have no issues. Even so, it is probably best to keep them away from direct light. In the short-term, a dark cupboard is sufficient as long as the temperature and humidity are reasonable.
Once the goal is to store cannabis seeds for months rather than days or weeks, everything changes. You need an airtight container, which you should store in a fridge. Include a vacuum-sealed container if you plan to store the seeds for several months or longer.
When storing cannabis seeds, you must ensure they are not exposed to germination conditions. This means keeping them away from direct light. Also, store in 20-30% humidity (8-10% for long-term storage) and a cool temperature. Keep the environment clean to avoid pests, and consider the tips above for germinating old seeds.
How To Store Your Cannabis Seeds
Seeds are where all begins, the care you give your seeds will influence not only in how your cannabis grows but in the final harvest.
1. Cannabis Seeds
Before talking about how to store seeds we need to remember that your cannabis seeds are alive. Before they germinate they are kind of in a state of hibernation, and like all living things, they can die.
When storing seeds you want to provide optimal conditions to ensure they are still good until you’re ready to sprout them. As we’re dealing with nature, you need to keep certain conditions or this can have an impact. Even though seeds have a hard shell and are fairly robust, you should have the following points in mind to avoid any kind of problems in the future.
2. Storing Seeds
When stored under perfect conditions, cannabis seeds can be viable for up to 10 years successfully. Seed storage is important for many reasons, either you’re a home grower waiting for the special occasion to grow that unique strain you just bought or seedbanks who need to stock seeds for the eventual sale. Whatever your reason may be for having seeds, remember that taking care of them is one of the most important things you can do for your harvest. A badly stored seed may not germinate, and if it does it may not grow properly. There are various parameters you’ll need to follow in order to store seeds long-term.
3. Ideal Conditions for Storing Seeds
There are three main factors that can affect seeds in a bad way:
If you’ve ever germinated cannabis seeds before, then you know that light is an important factor when it comes to the probability of the seed germinating or not. If your seeds are exposed to light for too long they may end up germinating before you’re ready to plant them.
Humidity is another incredibly important factor that can determine the success rate of your seeds as humidity is essentially what causes seeds to germinate. You don’t want them accidentally germinating, if they reach a certain humidity level they may start absorbing nutrients and end up too weak to grow normally, so you want to keep them in a relatively dry place. This obviously depends on your climate as there are places that have incredibly high humidity and others that are quite dry, which can directly impact how you have to store your seeds.
If there is as low as 8% humidity in the container it can cause fungi to appear inside and outside your seeds, at 40-60% your seeds will sprout and beyond that, they can drown in less than a day. Let’s quickly run through all the possible scenarios at different humidity levels:
- 81 – 100% – Seeds will not survive more than 12 hours, and could drown in less than 4 hours.
- 61 – 80% – Still a high risk of your seeds becoming inactive, with the possibility of them dying in less than 12 hours
- 31 – 60% – This is the accepted germination range, although many cultivators prefer a 40 to 60% range
- 21 – 30% – this is the ideal storage humidity range for cannabis seeds
- 9 – 20% – If seeds are left for longer than a day or two at this humidity level, they are at risk of becoming a breeding greyhound for a range of non-beneficial fungi. This fungus can kill the seed in less than 12 hours once it takes a proper foothold
- 0 – 8% – This is the perfect humidity range for pests and insects to wreak havoc on your seeds
The temperature at which you store your seeds is quite important. You’ll need to store them at around 6-8 celsius. You can keep them in your home fridge or even your freezer (however it’s usually not necessary).
We recommend storing them in the vegetable drawer or far back in the refrigerator and using a small cooler or something similar so the temperature doesn’t oscillate when opening the fridge door or if the power goes out. A good general rule is that the lower the temperature that you store those precious little beads of expectant joy, the longer they will last, and the less chance you have of unexpected germination. Growers who like to play with strain genetics and produce their own cross breeds through seed creation will usually have a special, dedicated fridge or freezer that they only use for their seeds.
If you are using your normal fridge/freezer for seed storage there are a few key things to keep in mind. First up, seeds are super light sensitive, so however you choose to store them, make sure they are in a light sealed container. It’s also good to ensure that your fridge or freezer has no frosting issues (as many older models will frost over without regular maintenance). This can lead to moisture being released if the temperature dips, which is not what you want if your seeds are stored there. If you have access to a vacuum sealer, then we recommend using it to first seal the seed fully – if you don’t then a snap or zip lock bag will do fine. Then put the bag inside a light-proof container.
4. Storing Seeds For Weeks
If you’re storing seeds for a couple of weeks it’s okay if you leave them in the original package as long as they are in a dark, dry, and cool place.
Usually, the package they come in is light-proof and water-proof, as long as you leave them in a relatively cool place like a drawer or something similar they will be good.
5. Storing Seeds For Months
If you’re storing your seeds for a couple of months it’s better if you store them in the refrigerator. This will guarantee the seeds don’t suffer from temperature swings. By keeping them in their original package or in a light-proof container you ensure they will be good for as long as you need.
6. Storing Seeds For Years
This usually applies to seed banks or breeders. If you need to store seeds for a really long time you can store them in a freezer. Even though it’s not necessary, it prevents your seeds from feeling the oscillation of temperatures even more. You can still store them in a fridge, it depends on what you prefer and what options you have available. Ideally, you want to store your seeds in a cool, dark, and dry place. When storing seeds in the fridge or freezer you can add silica gel sachets to ensure they’re completely dry. High humidity can trigger fungi to grow on your seeds. If your seeds get exposed to light or rapid changes in temperature it will trigger them to use up their nutrient stores before they ever see soil, meaning they won’t have the nutrients they need to germinate.
7. Germinating Your Cannabis Seeds
There is a handy, simple test to check if your seeds are bad. Just drop them in a cup of water (only once you are ready to actually germinate them). If they sink to the bottom and stay there then they are healthy and ready to be used. If the seeds float then there is a pretty high chance that they are not going to germinate. Don’t throw them out just yet though, give them 3 days or so to see if they do sprout a tap root. There are a couple of common methods used to germinate cannabis seeds. Let’s quickly run through them, starting with our favorite germination method to our least favorite.
The Wet Paper Towel Method
This method is simple, straightforward, and is the method of choice for most home growers. All you need is:
- A few paper towels (unperfumed and uncolored)
- Water that has a pH of 5.5 to 6.5 and at a temp of 22C or so
- A spray bottle
- Your cannabis seeds
- A tupperware container
Wet one of the paper towels and give it a light squeeze to remove any excess water. Lay it down flat and place 2 to 3 seeds onto it, with a spacing of about 2 centimeters between each seed. Then all you have to do is wet another paper towel, ring it out slightly, and place it on top of the seeds. Once this is all done place the envelope into the Tupperware container, and store the seeds in a dark, warm area.
This method should allow the seed to germinate in 2 to 3 days. Check the seeds every day, and if the paper towel is starting to dry out then give it a light spray with your pH water.
The Rockwool Block Method
This method is just as easy and straightforward as the paper towel method. The only reason it’s not number one on the list is that it requires the use of Rockwool, which is not as easily available for everyone as paper towels. The list of needed items is:
- Water that has a pH of 5.5 to 6.5 and at a temp of 22C or so
- Rockwool cubes
- A spray bottle
- Cannabis seeds
- A tupperware container
So, why is Rockwool a better germinating medium than paper towels? First up, paper towels are sometimes fragranced or colored. This is not good for cannabis seeds, and with Rockwool, you don’t need to worry about this at all. Rockwool also has great water retention properties, meaning you will not need to re-wet it as often as you do with a paper towel. It also provides a great home for your baby plant for the first 2 weeks or so, which gives you more time to get your growing medium set up. First up, soak the Rockwool cube overnight in your pH-adjusted water. Then just drop your seed into the opening on the top of the cube, and place the whole thing in a sealed container. You should see the tap root after 24 -72 hours.
Glass of Water Method
Look, there are a bunch of cannabis cultivators out there that love this method of germination, and yes it will work in most instances. But, in our experience, the rate of germination is not as high as the previous 2 ways laid out. It is the most simple method though. All you need to do is drop your seed (or seeds) into a glass of pH-adjusted water and let nature take its course. Be very careful when transplanting the seed to its growing medium. Of course, you can just plant the seed directly into your soil or coco-coir – but this makes it much harder to check on the progress of the germination. There are also a bunch of targeted products for seed germination on the market. These work well but are usually pretty high priced. Why drop a bunch of cash on a piece of equipment when a paper towel, a Tupperware container, and some oH adjusted water will do the exact same thing. You can also do a few key things to help your seed germinate quickly, especially if they are old seeds that haven’t been left in ideal conditions.
- Using finer-grade sandpaper, softly and gently score the outer shell of the seed. This helps the germinating moisture to penetrate the shell, which becomes tougher the older the seed is.
- If the outer shell is really thick and tough you can use a super sharp knife or even a scalpel to make a small incision in the shell.
- Carbonate water can help with germination, as can adding fulvic acid, or hydrogen peroxide to the water before soaking or spraying the seed and that’s it!
8. In Conclusion
It doesn’t matter if you’re a breeder, a grower, or a seed bank, always keep your seeds following the tips above. This way you ensure your so precious genetics will still germinate when you are ready to grow them.