How to store cannabis seeds
Since they are living organisms, cannabis seeds must be stored under certain temperature and humidity conditions, otherwise they gradually lose their germination potential, what may cause the germination process to take up to 6-7 days. In worst cases, seeds don’t even germinate, when they should have done it within the first 48-72 hours since we started the germination process.
Cannabis seeds stored with silica gel (Photo: Dinafem)
Since marijuana seeds are relatively expensive, we should know how to properly store them so we don’t waste money and time for not having our seeds correctly stored before the germination process begins.
Optimal conditions for storing cannabis seeds
Most grow shops and seed suppliers store their seeds in refrigeration chambers, thus creating the perfect environment to maximize the longevity of the seeds.
Temperatures between 4º and 8ºC and humidity levels between 10% and 20% are perfect to keep cannabis seeds in perfect conditions. Seeds should also be kept away from any light source, since it is another factor that can harm our seeds and decrease their germination potential.
Silica gel crystals absorve humidity
Thus, the best way to store our seeds can be an opaque, airtight container containing few silica gel sachets to keep humidity levels low (remember that the ideal humidity should be 10-20%). Put the container in the fridge; normally, people have their refrigerators at 4ºC, so putting the container inside the vegetble shelf is the best option, since temperatures are slightly higher there (as we mentioned, seeds should be kept at 4-8ºC).
Cannabis seeds can be perfectly viable after more than 7-8 years if kept in good conditions, what can be reduced to few years (2-3) in case of not meeting these parameters. We have recently (2015) tested 25 seeds harvested in 2007 with a 24/25 germination ratio. Those seeds were kept as this post explains.
You can read our article about how to germinate cannabis seeds for further information on the germination process.
The articles published by Alchimiaweb, S.L. are reserved for adult clients only. We would like to remind our customers that cannabis seeds are not listed in the European Community catalogue. They are products intended for genetic conservation and collecting, in no case for cultivation. In some countries it is strictly forbidden to germinate cannabis seeds, other than those authorised by the European Union. We recommend our customers not to infringe the law in any way, we are not responsible for their use.
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 Marijuana Seeds Properly
T here’s a lot of reasons to store marijuana seeds rather than just planting them in soil and letting them do their work. Sometimes you have some seeds leftover from your new favorite weed strain and don’t have the space available where you live to plant it. Other times, you’re buying seeds for later use once you’ve got the time and energy for your weed growing project. Maybe you’d like to hold on to precious genetics until you can seek out another strain to cross it to. Sometimes you’re just stocking up for an uncertain future.
Whatever the reason, you need to be sure those marijuana seeds stay viable in the long term. Properly stored marijuana seeds can last for up to five years and still remain viable, and some strains have been reported sprouting at ten years or more.
However, proper storage is not as easy as it seems, since seeds are looking for any excuse to start sprouting and there are a number of factors that tell the seeds that the time is right to stretch out their roots and branches. Store your marijuana seeds in the wrong conditions and they might end up dead, rotting, or diseased by the time you’re ready to introduce them to the soil.
Fundamentals of Marijuana Seed Storage
First, let’s go over the five main factors to consider when it comes to how to store marijuana seeds, especially for the long term.
Keep Your Marijuana Seeds Cool
When it comes to preserving your marijuana seeds for future planting, temperature is the main consideration. In nature, heat is what tells the seed that the winter’s over, which means that it’s time to break open and start sending roots down and shoots up.
If your marijuana seed is not in the soil, this means that the plant matter inside the seed will begin to germinate. The shell will crack open, letting the plant matter out and moisture, bacteria, and pests in. Without soil to thrive in, the marijuana seed will begin to rot.
41℉ (5 ℃) is the absolute warmest you want your long-term storage spot to be, with the sweet spot being somewhere around 38 ℉.
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It’s very important that this temperature remains stable for the long term. If you are refrigerating your marijuana seeds, your best bet is to place them in a separate unit or a spot near the back. Every time that you open your fridge the temperature fluctuates, which can harm the marijuana seeds over time.
While it’s up for debate whether freezing marijuana seeds is an effective method for long term storage, we don’t recommend it unless you know exactly how to cure and prepare your seeds. Otherwise, the frozen water in the seed’s cells can expand, destroying the cell wall and killing the seed.
Watch out for Humidity
Humidity is another enemy in your battle for storing cannabis seeds long-term because any hint of moisture is another clue to the seed that it’s time to stretch its leafy arms and legs. If the marijuana seed shell breaches before it’s in the soil, rot can set in.
However, you don’t want your marijuana seed too dry either. A humidity level of about 5% is the maximum that you want to allow in order to keep the waxy, protective layer surrounding the seed intact without triggering the seed to split open.
Store Your Marijuana Seeds in an Airtight Container
Besides being dark, you want to expose your marijuana seeds to as little oxygen and carbon dioxide as possible. These gasses are what growing plants breathe, as well as the pests that consume them.
If you’re storing cannabis seeds by refrigerating them, make your container as airtight as possible. If you have some vacuum-sealed plastic on hand, even better.
Keep Your Marijuana Seeds in The Dark
Much like heat and humidity, light tells that marijuana seed to wake up because it’s time to spring forth. Even if it’s a halogen bulb inside your refrigerator and not the sun itself, the seed’s natural optimism can still start the flowering process.
Light exposure over time can also damage the surface of the seed, which in turn will damage what’s stored underneath. The solution, much like storing cannabis flower and other products, is to keep your marijuana seeds in a dark or opaque container. Without exposure to light, they’ll keep dozing long term.
Your Marijuana Seed’s Genetics
Some weed strains (and some specific batches of those strains) naturally produce seeds that are hardier and longer-lasting than others. This plays a role in how long you can expect your marijuana seeds to remain viable, so be sure to do some research beforehand.
Storage Methods for Marijuana Seeds
Now that we’ve covered how temperature, humidity, light, air, and genetics work against you when it comes to seed storage, let’s cover the best marijuana seed storage methods.
If you’re storing your marijuana seeds for the short term (a couple of weeks or months), a standard mailing envelope or a tan coin envelope will do in a pinch. If the envelope paper is thick enough, it will protect the seeds from the most harmful ambient light. If the envelope is stored in a cool, dry, dark, and temperature-stable spot like the back of a closet or a drawer, the marijuana seeds should also stay dormant in the short term.
Plus, an envelope makes it easy to write the name of the weed strain, the date of storage, and any other important notes you have. If you want to be extra safe about it, throw some grains of rice or a desiccant pack in there to regulate the humidity.
Of course, this method is only as good at the stability of your home’s climate. If you live in a humid area prone to frequent storms or weather fluctuations like Florida, envelopes will only get you so far without ruining your marijuana seeds.
Unlike a mailing envelope, glass jars are airtight, which makes them much more suitable for storing cannabis seeds long-term. Because many types of plastic can let small amounts of water in overtime, it’s highly recommended that you use glass with rubber stoppers. When storing cannabis seeds long term, you should also throw in a desiccant pack to keep the humidity stable.
Be sure to separate the pack from the marijuana seeds with a couple cotton balls or a paper towel. This will help absorb excess moisture at the start as well. If you have a method to vacuum seal the jar even better. Wrap the jar in something opaque and you’re all set. Marijuana seeds stored at a stable room temperature can last for over a year. Refrigerated they can last a couple years.
If you’re looking to store your cannabis seeds long term, vacuum sealing your seeds in thick Mylar bags can keep your seeds viable for up to half a decade. Because the bags are designed for long-term storage, they’ll work well for your marijuana seeds as long as you make sure they were stored at the right humidity (again, a desiccant pack helps with this) and away from the light. This is one of the best options if you’re refrigerating marijuana seeds.
Seeds of Wisdom
In conclusion, storing cannabis seeds for the long haul is relatively simple. They will stay viable as long as they’re kept away from heat, light, moisture, and air. The more care you put into your storage method, the longer your marijuana seeds will last. However, when it comes to planting marijuana seeds with the most chance of success, sooner is always better.
What are your best methods for storing seeds? Share in the comments below!