You can usually save a lot of money by buying larger quantities of seeds at once.
And many seed banks give you quite a few free seeds on top of your order.
But then you have a problem.
You don’t have the space to plant all of those seeds at once. So you’d like to save some of them and use them at a later date. But will the seeds last long enough?
We have good news for you. Cannabis seeds can last a very long time. Let’s find out just how long and what you can do to extend their life.
How Long Do Marijuana Seeds Last?
Cannabis seeds can last for more than 5 years. But this assumes you have quality seeds and you store them properly. Otherwise the lifespan will be much shorter.
However, it is important to note that the chance of successful germination decreases the older a seed gets. We definitely recommend you use your seeds as quickly as possible, even if you bought a top quality strain from the one of the best seed banks online.
With good seeds, even if you simply store them in an envelope at room temperature, you can expect them to last up to a year or two. Taking care of the factors below, you can extend that quite a bit.
Factors Affecting How Long Weed Seeds Are Good For
Obviously, genetics are a major factor. Good quality seeds last longer than low quality ones. Poor seeds can go bad quickly.
The way the seeds were handled also plays a role. If the seed bank where you bought them stores their seeds correctly and sends them in the mail in such a way that they are protected from damage, then they will last a long time.
Those are things over which you have no control, apart from choosing a top quality seed bank. What you do control is how you treat your seeds after they arrive.
Try to provide as close to ideal conditions as possible. We’ll get into the best way to store them in a minute. First let’s look at the main factors that affect longevity of cannabis seeds.
Light
Light signals the seeds to begin preparing for germination. Even if they don’t germinate, because the other factors necessary are not present, the chemical processes for germination can be triggered and then the seeds will not be able to germinate later on, when the time actually comes. If you want to ensure your seeds stay good as long as possible, keep them in the dark.
Heat
High temperatures also signal germination. You want to keep your seeds in a location that is as cool as possible, without freezing. You can certainly keep them at room temperature, but to maximize their lifespan, try to keep them at temperatures from 42° and 46° F, which is around 6° to 8° C.
Moisture
Moisture also sends the signal for germination to begin. Moreover, a moist environment can lead to rotting. Ideally, you want to preserve your seeds in a dry environment, with a relative humidity of 8% to 10%.
Environmental Fluctuations
Worse than any of the above are fluctuations in the environment. Even if you just keep the seeds in a drawer in your kitchen, at regular room temperature and humidity, they will last for a good while. Perhaps even a year or two. But if the humidity, the temperature and the light levels keep changing, that lifespan becomes much shorter.
Oxygen
Finally, seeds last much longer in a vacuum. They will be fine for a long time if kept in earth’s regular atmosphere, but a vacuum is much better. Even just keeping them in a sealed off location does wonders. They’ll have oxygen, but they won’t have a steady supply of fresh air. Not only does a lack of fresh air prevent germination, it also makes it more difficult for pests to thrive.
How To Make Cannabis Seeds Last Longer
Based on the factors above that affect how long weed seeds last, we can deduce that keeping your seeds in a cool, dry, dark place will go a long way toward ensuring they last a long time.
If you want to make sure your marijuana seeds last longer, first put them inside a vacuum sealed container. They generally arrive well-packed from the seed bank and we recommend just using the package they came in, if you haven’t already opened it.
If you have, use container that is not porous and seals completely, and remove all of the air. A vacuum is ideal, but not a necessity, so if you do not have a vacuum sealer, you can simply put them in a dark paper envelope.
Put this package inside a glass mason jar. The package should already be dark, but it might be a good idea to wrap the mason jar, too, so that you can ensure complete darkness inside. Add some desiccant, like silica gel packs, to ensure a low humidity level.
Put this mason jar inside a refrigerator. Ideally, use a fridge that does not see daily use, to avoid the temperature and humidity fluctuations that come with opening the door.
If you follow those brief guidelines, your seeds will stay viable for many years. Our article on storing marijuana seeds correctly has much more.
How To Tell If Cannabis Seeds Are No Longer Good
Say you’ve got some seeds you’ve kept for a long time. Is there any way to tell if they have lasted, or if they are no longer any good?
There are some indications that seeds have not lasted, but many seeds that look fine still won’t germinate. If a seed looks good, the only way to tell if it has stood the test of time is to actually try germinating it.
So what are the indications of seeds that didn’t last?
The most obvious are cracks in the seed. If you see cracks in the hard outer shell, the seed is most likely no longer viable. Once the genetic material inside the seed is exposed, it is unlikely to germinate properly.
The outer shell itself can give some indication, too. If it is slightly pliable, so that you can gently squeeze it, without crushing it, then your seed is likely good. If the shell crushes easily when you apply a bit of pressure, the seed is useless (and now crushed).
The look of the seed gives you clues as well. It should have a thin waxy coating and should be dark. Good seeds are generally, brown, black or gray, and they generally have stripes or spots. That said, some strains have seeds that are lighter, so you want to make sure you know what your particular strain should look like.
Finally, you can do the water test, which actually works with seeds of all types, not just marijuana seeds.
For this test, simply drop the seeds into a cup of warm water and leave them there a few hours. If they sink to the bottom, they are good for germination. If they stay floating at the top, they are likely dead.
Naturally, you should only do this test on seeds you are getting ready to germinate. Once you’ve soaked a seed in water, you can’t then expect it to last much longer in storage.
How Long Cannabis Seeds Last: Final Thoughts
Good quality seeds can last a very long time. Under the right conditions, they can last 5 years or more. But you need to make sure to keep them in a cool, dark and dry place and to maintain steady conditions with no fluctuations.
And, as mentioned, get your seeds from a reputable seed bank, like ILGM or Crop King Seeds. Do not buy from a seed bank that is known to ship bad seeds. They tend to violate all of the recommendations we gave here. Read our Dutch Seed Shop review for an example of one such seed store.
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