First-time cannabis growers have a lot of things to learn at once, and one of them is proper seed storage. Many times you end up not using all of the seeds Weed seeds can survive in the soil for years before they germinate and grow.
How Long Do Marijuana Seeds Last?
First-time cannabis growers have a lot of things to learn at once, and one of them is proper seed storage. Many times you end up not using all of the seeds that you purchased, or you decided to keep some of the seeds your own cannabis plants have produced because you want to keep the genetics going, so you want to store them safely.
So, can cannabis seeds be stored without losing their viability to germinate? How long do marijuana seeds last if stored properly? We’ll cover these questions in today’s article as well as give you some tips on how to store your seeds the right way, so let’s get started.
Do Cannabis Seeds Ever Go Bad?
Cannabis seeds are much like any other plant seed – they have a waxy outer shell that protects the embryonic material on the inside, and as long as there is no damage to the shell, the seed will remain viable for germination.
However, if stored for too long without germinating or if it’s improperly stored, the weed seed can dry out to the point where it cracks, which exposes the genetic material inside, making it unfit for germination.
Another scenario would be for the outer shell to dry out and harden to the point where moisture or air won’t be able to get in, in which case the embryonic material won’t be able to survive.
The Three Main Factors That Influence the Shelf Life of Cannabis Seeds
The shelf life of cannabis seeds can be influenced by the genetics of the cannabis strain, but this is only minor compared to how they’re stored. Quality seeds may be more resilient, but if not stored properly, their lifespan will be impacted.
To preserve your weed seeds, the goal is to keep them from germinating prematurely, and to do that, you should pay close attention to the three factors that greatly influence their shelf life.
Light is one of the propagators of germination because it signals them that it’s time to wake up and sprout. If your seeds are exposed to light, crucial chemical changes will happen within the seed, and even if it doesn’t germinate now, these changes will prevent it from germinating later because the natural process will be disrupted.
Warm temperatures also signal that it’s time for germination. And not only that, but warm temperatures can increase the moisture, and excess moisture creates a breeding ground for mold and rot. Therefore, keeping the seeds at a temperature between 42°F and 46°F is recommended.
Humidity is the third factor that influences the shelf life of weed seeds and it’s also closely related to temperature. The relative humidity is a crucial element in seed germination, but when storing seeds, you want to keep it at a minimum. Relative humidity between 20% to 30% would be best – you still want some moisture so that the seeds don’t dry out completely.
How Long Do Marijuana Seeds Last?
Most seed banks would recommend that you plant the seeds within a year, but the truth is, when stored correctly, cannabis seeds can remain viable for up to five years. In rare cases, some growers have managed to keep them for seven to ten years, but this is definitely not common. You should know that the longer they are stored, the longer it will take to germinate as they will gradually lose their viability. Old seeds definitely take longer to sprout than new ones, but they do sprout nonetheless.
How to Tell That Your Weed Seeds Are Still Viable
There are some signs you can look for to check if your weed seeds are still viable for germination.
- If the seeds have a dark color, like dark brown or grey, or even black, it means that the outer shell is intact and that they’re still good to use;
- The seeds should have a waxy coating that looks shiny because it means that it’s still able to retain moisture;
- If you can lightly and carefully squeeze the seed without it cracking immediately, it’s probably still viable;
- Healthy weed seeds don’t have any cracks or holes, so if the outer shell isn’t damaged, the seed is okay.
How to Properly Store Cannabis Seeds to Prolong Their Shelf Life
The key to storing cannabis seeds is to keep them in a stable environment without changes. Frequent changes stress the seeds and cause them to use up their nutrient reserve, which inevitably makes them useless in the end.
Store Them In a Tightly Sealed Container
Cannabis seeds need some degree of oxygen in their environment, but too much of it can also invite bacteria and parasites, and not to mention, it could dry out the seeds. Therefore, keeping them in an airtight container is the safest way to make sure they remain intact.
Keep Them Somewhere With a Low Room Temperature
As we previously said, warm temperatures will incite germination, so storing your seeds in a cool place is ideal. This could be the basement, the pantry, or a storage room – anything works as long as the place has a constant low room temperature. Pay close attention to this, especially if you live somewhere warm.
Watch the Humidity Levels
High humidity poses a danger to cannabis seeds, not only because it makes them sprout when they shouldn’t, but it can also invite mold. Therefore, storing them in a relatively dry place would be great. If you’re unable to store them somewhere dry, you can place cotton balls in the container to soak up excess moisture or even use a food-grade desiccant, like silica gel packs, or even Boveda packs, as they’re specifically designed for these purposes.
Put Them In a Dark Place
Finally, weed seeds need to be protected from light for obvious reasons. Even if you use an opaque container (which is recommended), you should still store them in a dark place. You can also use a mason jar or any kind of clear glass container, but you’ll have to make sure it’s hidden from the light.
Plastic containers and plastic bags are not recommended because they encourage excess moisture and they let air in. Use them only for short-term storage if you absolutely have to.
For Long-Term Storage, You Can Freeze the Marijuana Seeds
Cannabis seeds can stay good for a few years if you meet the conditions, but you can also freeze them for long-term storage. If you end up freezing them, it’s best that you store them in a vacuum seal and remember to keep them frozen until you decide to use them. Thawed and refrozen seeds will lose their viability, so you should avoid this.
The Takeaway – Store Them In a Dark, Cool, and Dry Place for Up to Five Years
Even though seed banks recommend that you plant weed seeds within a year after buying them, they can have a shelf life of up to five years when stored properly. If, that is, you store them in a stable environment without temperature changes, high humidity, and light. Or in other words, a cool, dark, and dry place. Storing them in an opaque airtight container is ideal, but you can also freeze them if you want to. Old seeds take longer to germinate, but as long as their shell is not damaged and they still look healthy, they should be good to use.
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How long do weed seeds survive in the soil?
CORVALLIS – Weed seeds can survive in the soil for years before they germinate and grow, according to Jed Colquhoun, weed specialist with the Oregon State University Extension Service.
Why should home gardeners care?
“If you combine the longevity of seeds in the soil with the fact that weeds such as common lambsquarters can produce over 500,000 seeds per plant, the incentive to hand weed your garden becomes much greater,” said Colquhoun.
“Prevention is the most effective form of weed control,” he said.
Here are some basics on weed seed biology:
Undisturbed weed seeds tend to persist longer than seeds subjected to periodic tillage. Weed seeds in deeply worked soil tend to last longer than seeds in shallowly worked soil. Seeds deep in the soil are “stored” below the germination zone.
Grass seeds tend to be less persistent than broadleaf weed seeds.
The number of surviving seeds of most weed species declines rapidly the first year. But thereafter the rate of weed seed decline slows. Some seeds can persist for decades.
As many as 130 million seeds per plow acre were found in a Minnesota study.
Different species of weeds have seeds that last varying numbers of years in the soil. The scientific literature provides some information about seed longevity, including:
- Brome grass seed seldom lasts more than two years.
- Annual ryegrass – up to nine years.
- Perennial ryegrass – up to three years.
- Annual bluegrass – up to about five years.
- Wild oats – three to six years, but longer in deep soil.
- Jointed goatgrass – three to five-and-a-half years.
- Barnyardgrass – up to 13 years.
- Quackgrass – up to four years.
- Common velvetgrass – 10 years or more.
- Mustards – are long lived. Seeds excavated from a monastery in Denmark were dated to be 600 years old and 11 of them germinated. More commonly, mustard seeds last for decades.
- Lambsquarters – may last up to four decades.
- Russian thistle (tumbleweed) – short lived, most live only a year.
- Wild carrot – several years.
- Curly dock – more than a decade.
- Canada thistle – more than two decades.
- Field bindweed – more than 50 years.
- Leafy spurge – at least a few years.
- Common groundsel – most die within a year.
Scientists found lotus seeds in Manchuria that germinated after over 1,000 years, said Colquhoun.