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How long do marijuana seeds last?
And how to store them

By Caroline | October 8th, 2020

If you've read our previous article on why you should grow your own marijuana, you learned that growing your own weed is fun, cheaper in the long run, and a sure way to never run out of something to smoke. 

If you, like yours truly here are suffering from FOMO (for the non-hipsters among us: that's short for "Fear Of Missing Out" ;-)  and subscribed to a plethora of newsletters from various seedbanks to never miss out on a solid bargain, a certain luxury problem could occur: What do you do with all these newly acquired treasures when you don't have an immediate use for them? 

While nothing lasts forever, along the way I’ve learned that, if stored properly, marijuana seeds will remain viable for quite some while. With this article, I hope to finally answer that frequently asked question: how long do marijuana seeds last?

How Long do marijuana seeds last after storing them?

The short answer is several years or up to 5 years, depending on the circumstances. 

The fact remains, that seeds exceeding that storage period are significantly harder to germinate.

So, you’ve scored big during the annual Black Friday sale and stocked up on all your favorites but then you remember, planting is months away.

Make sure your bargain isn’t going to cost you and ensure the viability of your seeds when planting time arrives with proper seed storage. It doesn’t take much, especially if you are storing seeds short term (less than two years).

If you plan to store your seeds for longer, it requires a few more steps to protect the long-term viability of the seed. But for short-term storage, a cool, dark, and dry spot are all you need.

Mother Nature’s designed them to respond to their environment within particular heat and moisture to signal the seed when it’s time to germinate. 

Which, in nature is key to the survival of the plant, but not so convenient if you don’t have the intention of using them right away.

How to Store Marijuana Seeds

Marijuana seeds are living organisms which, when correctly stored, remain dormant. All seeds need to germinate is humidity and temperatures that are favorable. 

Make sure your seeds don’t prematurely sprout by storing them in a spot that doesn’t have the right humidity levels and ensure the seeds are dry before sealing them in a container

Key factors for your storage conditions environment

  • Humidity: Moisture is an especially important factor if you are freezing or refrigerating your seeds. If seeds are too wet, they can rot in the refrigerator or crystallize and suffer frost damage in the freezer. If you store seeds in the refrigerator or freezer, place the packets in an air-tight container and ensure you've properly dried the seeds, to begin with. As Cannabis expert Ryan Riley explains in Ryan Riley’s Growing Elite Marijuana
  • Temperature: Consistency is key when it comes to temperature. So, you should avoid storing seeds in a spot that isn't climate-controlled, like a garage or shed, where temperature can fluctuate wildly, especially during summer. 6 °C or lower would be ideal in terms of temperature. Unwanted fungi and bacteria in and on the seed may otherwise build up rapidly in a moist environment. High moisture levels and high temperatures will kill cannabis seeds as quickly as an invasion of microorganisms and insects, so be careful. How long marijuana seeds last, mainly depends on each 41°F / 5°C) temperature reduction in the storage environment. The recommended temperature is at least 41°F /5°C) (yes, this is slightly warmer than regular fridges). The cooler the temperature the more slowly seed vitality declines. This rule apparently continues to apply even at temperatures below freezing. At 41 °F (5 °C)
  • Light: is necessary for germination; over-exposure may bring seeds to come out of their dormant state and encourage them to mutate. By keeping them in the darkness you ensure that they will remain dormant (provided that you’ve also taken the other requirements into account of course).

When you meet the above-storing conditions, storing cannabis for five years while maintaining high germination rates is entirely do-able.

Riley also advises making sure to label the container/package with the strain name, quantity, and date of storage to make storing easier.

In our article How to germinate weed seeds, we will teach you various germination methods that can make even the Methuselah's among seeds sprout.

 

What is the best place to store your seeds?

  • Basement: Cool ✔ Dark ✔ That’s two out of three requirements down. As for moisture control: Experts swear by placing the seed in a closed container along with some uncooked rice to absorb any moisture (don’t forget to replace the rice regularly). A food-grade silica bag will also do the trick nicely. 
  • Fridge: the best option, I think is to store them in refrigerators at a temperature between 6 and 8 degrees Celsius, and with relative humidity levels between 20% and 30%. And sheltered from light, of course. This spot checks all the boxes. In regard to the best place in your refrigerator, the crisper is a good choice, as it is a little warmer than the rest of the fridge.
  • Freezer: one of the most popular places to keep your stash. The average freezer is about -15 °F dark and has a minimum of temperature fluctuations. A word of caution though! Some seedbanks keep a large stock, so you are at risk that the seeds you purchased were frozen and have now thawed. When the seeds thaw, they attract moisture. Re-freezing them causes crystallization and causes the seeds to perish! 

 

Where do you keep your seeds in?

The freezer resolves the temperature fluctuations issue since you open it a lot less than the fridge door. Freezing seeds does not hurt them and can greatly extend their lifespan if done properly. ... If you are saving seeds from a seed packet where you didn't use all the seeds, keep the packet and put it into a Ziploc baggie.

We’ve now determined that keeping them away from moisture in a climate-controlled environment and limit the exposure to light to a minimum will significantly prolong their shelf life. Keeping them in the Ziplock bag they came in seems like the obvious thing to do. Or is there a better way?

If you plan on only storing them for a few months, cannabis seeds should do fine in a grip seal bag, placed in a mason jar, or some other type of airtight container. For more long-term storage, a vacuum-sealed package is a much more popular option. Many seasoned growers like to add a food-grade desiccant or some uncooked rice to their package as well.

What about a metal box or vault? That’s a big no. The metal will kill the seeds.

Are there disadvantages to old seeds?

Even if you’re organized, methodical, and careful about storing seeds, older seeds could be more difficult to germinate, resulting in more fragile plants, a thinner stem, and require more care and attention as seedlings.

There are a few tips and tricks to apply in order to increase your chances of successful germination.

  • Sandpaper method: Some breeders use sandpaper (see video below) for older seeds. Lightly and gently scrape off the outer layer of the seed, creating micro-abrasions that help them absorb moisture more easily and then soak for 12 hours.
  • Hydrogen peroxide: Soak the seeds in a glass of water with a few drops of hydrogen peroxide, for 24 hours at a temperature of 28 °C. The hydrogen peroxide softens the shell and facilitates the water's absorption.

How long do marijuana seeds last? Let's recap...

Saving cannabis seeds is a widely used method for preserving unique genetic varieties that one has particularly enjoyed or that worked very well when planted. 

The most important factors when storing your seeds are keeping them cool, dark, and dry. Maintaining a constant environment with little or no fluctuation is vital to ensure the stability of your stored seeds.

You should bear in mind that humidity and temperature are the two most significant agents to have a quality storage system of marijuana seeds. Indeed, marijuana seeds are susceptible to their surroundings, since they dry out easily in a dry atmosphere and absorb moisture in a humid area. In every 1% reduction in the confined moisture, the life of the cannabis seeds inside the container in also prolonged.

So, there you finally have your answer as to how long do marijuana seeds last. Properly storing your seeds takes a little more effort than one would think but I ensure you, that extra care will pay off.

What’s your preferred way of storing your seeds? I’m interested in hearing your thoughts!

Article by:

Caroline


Educated by one of the best breeders in the Netherlands, I chose to combine my passion for writing with the fascinating world of cannabis cultivation. What are the best strains for which occasion, what are the effects, and how to use responsibly? Let me take you on a journey.



Contributors:
Bob

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