Weed seeds can survive in the soil for years before they germinate and grow. If you have some extra cannabis seeds lying around, you're probably wondering how long you can expect them to last.
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.
How Long Do Marijuana Seeds Last? (Explained)
If you have some extra cannabis seeds lying around, you’re probably wondering how long you can expect them to last.
The germination rate of Marijuana seeds naturally declines over time. However, if stored correctly, your seeds can last for up to 5 years. However, to last that long, they need to be good quality and be stored in a cool, dry, and dark place.
Read on to find out how to store your seeds correctly to make them last longer.
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How Long Do Marijuana Seeds Last?
Cannabis seeds can last for a very long time if they are stored in the correct conditions. The ideal storage temperature for cannabis seeds is between 7-10°C (45-50°F), with a humidity level of around 55%. Under these conditions, your cannabis seeds should last for many years.
However, it is worth noting that the shelf life of cannabis seeds will decrease if they are exposed to light, heat, or excessive moisture. Therefore, it is important to store your seeds in an airtight container in a cool, dark place.
If you are planning on germinating your seeds at some point in the future, it is worth testing a few to check their viability first. The best way to do this is to place the seeds in a cup of water overnight. After 24 hours, check to see if any of the seeds have sunk to the bottom of the cup. If they have, this indicates that they are still viable and should germinate successfully.
How To Tell If Your Cannabis Seeds Are Still Good
Many growers have experienced the frustration of planting cannabis seeds, only to have them fail to germinate. If you’re wondering whether your stored cannabis Seeds are still good, there are a few things you can do to test them. One simple way is to do the float test: Take a glass of distilled water and drop it in your seed. If it sinks, it’s probably still good. If it floats, it’s not going to live.
Also, give the seed a light squeeze between your fingers. Healthy cannabis seeds should be firm, with a dark brown or black coloration. If they’re pale or green, they’re not going to sprout. If they’re hard and brittle, they might be too old.
The best way to tell if your seeds are still good is to try germinating them. Plant two or three seeds in moistened soil, and wait a week or two to see if anything happens. This method isn’t foolproof (sometimes seeds just don’t want to germinate), but it’s the most reliable way to tell if your precious cannabis seeds are still alive and viable.
Will Cracked Marijuana Seeds Still Germinate?
The simple answer is yes. However, it is worth noting that the germination rate for cracked seeds is often lower than for intact seeds. In addition, the process of germinating a cracked seed can be more difficult and time-consuming. When a seed is cracked, the protective outer coat is damaged, exposing the delicate inner tissue to the elements. This makes it more susceptible to infection and less able to absorb moisture. As a result, it can take longer for a cracked seed to germinate, and the plant that emerges may be weaker than one grown from a healthy seed. Despite these challenges, it is still possible to successfully grow a plant from a cracked marijuana seed. With patience and care, you can end up with a bountiful harvest of high-quality buds.
How To Make Your Marijuana Seeds Last Longer?
Let’s take a look at some of the main ways you can make your marijuana seeds last longer.
1. Store Them Properly
You can prolong the shelf life of your marijuana seeds by storing them properly. Keep them in a cool, dark place, like a pantry or cupboard. You can also store them in the fridge, but make sure they’re in an airtight container so they don’t dry out.
If you live in a humid climate, it’s a good idea to store your seeds in the fridge or freezer to prevent them from going bad.
If you have a lot of seeds, you can also store them in a Mason jar or vacuum-sealed bag. Just make sure to label the container with the date so you know when they were stored.
A Ziplock bag works well when you want to store seeds for a short duration of around 5-6 months. Any longer than that and your seeds may start to go bad.
Put your seeds into your bag, try to remove as much air as possible and then seal it tightly. Then keep your bag in a cool and dark place.
A step further than a regular Ziplock bag, a vacuum-sealed bag will ensure that there is no air left inside your bag.
This will allow you to store your seeds for a longer period.
You will still need to ensure to keep it in a cool, dark environment.
Some seed banks deliver seeds in a vacuum-sealed package that can store them until they’re ready for planting.
Another great method for long term storage is keeping your seeds in an airtight container.
Glass containers are preferable as they are more resistant to heat and UV ray damage.
Just make sure to keep them away from light.
If you are looking to store your seeds for over a year, you can refrigerate them.
Refrigerators offer constant low temperatures and dark and moisture-free environment.
Keep your seeds at the back of your fridge so that they are away from any potential moisture or temperature changes from opening it often.
Make sure the container or bag your seeds are in is airtight and heatproof.
You will also want to make sure that your fridge is “no-frost” or has a no-frost area to shield seeds from frost damage.
Freezing marijuana seeds is a debated method.
Freezing is used by some to store their seeds for years on end.
Others say that it ends up killing seeds instead of protecting them.
Some growers even believe that freezing seeds can damage their internal cells.
Using special laboratories and equipment can allow for the careful freezing of seeds, but this is not a very cheap or accessible option for many.
Now that we have covered everything there is to know about how long marijuana seeds last and how to store them, you are all ready to begin your growing adventure. We’ve made sure to cover all our bases- from basic seed facts to how to choose the best seed bank.
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Hey, I’m James! The founder and head writer here at GreenBudGuru.com. I started this site to share my passion and knowledge of all things cannabis. I used to work as a budtender in central Amsterdam, and have over 7 years of growing experience.
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Hi, I’m James, the founder of GreenBudGuru. I started this site in 2018 to help new cannabis growers avoid the common mistakes that I made as a beginner with easy-to-follow guides. GBG is now read and trusted by over 100,000 people each month.