How Long Does Weed Stay Good?

If you’ve found some weed in your house that’s been there for a long time, or you can’t remember where it came from, then you might wonder how long does weed stay good. That’s a perfectly natural question to ask, and in this article, we will answer it. 

You mustn’t just go ahead and use the weed anyway because there is such a thing as stale weed. Plus, if it’s been there for years, then it might end up having zero potency. We’ll explain that as well. 

To give you an overview, here’s what we’ll cover:

  • What makes weed fresh
  • How to tell if weed has gone off
  • How long does weed stay good in a plastic bag? 
  • How long does weed stay good in a jar?  

Once you’ve read through all of this, you’ll know exactly what to do with the weed you have, and weed you get hold of in the future.

What makes weed fresh?

Weed grinder with crushed cannabis flowers and joints

There is a range of conditions that determine whether weed is fresh or not. But if you’ve had the weed for longer than a year, then chances are it will have gone off. We’ll discuss that more in the next section.

Three conditions affect the freshness of weed, and these are humidity, temperature, and light. No single condition is more important than the others, and they all have to be balanced. But if you manage to do that with your storage method, then you’ll have long-lasting weed.


If you want to ensure that your weed stays fresh and is good to smoke, you won’t want to neglect the humidity. If the humidity of the environment your weed is stored in is excessive, then it can go rotten and moldy. 

When that happens, you can get very ill if you consume it. To ensure your humidity is correct, measure it and keep it between 59-63%. That will also help your weed retain its flavor and consistency. 

Dried cannabis buds in glass jar and on a flat surface

On the other hand, if your humidity is too low, then you can find your weed crumbles and dries out. 


Another key factor you need to consider is the temperature of your weed. It needs to be kept dry, and cool. But there is no need to go over the top with this. If you put your weed in freezing conditions, then you can damage the plant easily. That’s because when you transport it, temperatures will change rapidly. This can cause plant trichomes to break down. 

At the same time, you don’t want to put your weed out in the sun, because this will lower the THC levels by converting it to CBN, which won’t give you a good high. 


No plant can thrive without light, and cannabis is no exception. It’s a key factor in determining how long does weed stay good. We noted above that the sun can decrease THC levels, and it does this through UV rays. UV rays can also break down CBD

Cannabis buds and cbd oil ion a flat surface   with indoor lighting

Light levels also act as a preservative if they’re correct. That means good lighting will prolong the usefulness of your weed, so it’s not something you’ll want to ignore. 

How to tell if weed has gone off

There are several signs that weed is going stale, and these are as follows: 

  • Low THC levels 
  • Mold
  • Texture changes 
  • Scent 

In turn, we’ll talk about each one, giving you a basic overview of how to test for each sign. 

Low THC levels 

Chemical composition of THC with cannabis leaves and seeds on the background

The longer you leave weed alone, the lower the THC will be. After 12 months, you can expect THC to have declined by 17%. After 2 years, 27%, and after three years, 35%. If your weed is even older, then it may have less than half of the THC it once did. 

That makes old weed much less potent when smoked, which means it’s going to be disappointing for you if you try it. 


This is quite easy to spot, as it will be very visible on the surface of your weed. Mold develops after exposure to high levels of humidity or excessive moisture. You mustn’t smoke weed if it’s moldy, because it’s bad for your health. 

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Purple Kush Autoflower 
Plant Type100% Indica
THCUp to 22%
CBDInsignificant amounts
Grow DifficultyModerate
ClimateIndoors | Mold Resistant | Continental
Plant SizeCompact
Flowering Time8 weeks
Yields4 to 6 oz per 3x3ft
how long does weed stay good

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Blue Cheese Feminized 
Plant Type80% Indica 20% Sativa
THCUp to 19%
CBDInsignificant amount
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ClimateIndoors | Continental | Mold Resistant
Plant SizeAverage
Flowering Time8 weeks
Yields5 to 9 oz per 3x3ft

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Super Lemon Haze 
Plant Type20% Indica 80% Sativa
THCUp to 22%
CBDInsignificant amounts
Grow DifficultyModerate
ClimateIndoors | Mediterranean | Mold Resistant
Plant SizeTall
Flowering Time9 weeks
Yields21 to 25 oz per 3x3ft

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If you grab hold of the weed that you’re testing, and it feels like a sponge, then that’s a sign of dampness. That could mean mold. If the weed falls apart in your hands, then it’s out-of-date and should be binned.  


If there is anything odd about how your weed smells, that’s a surefire sign that it’s going off. The best thing to do if this is the case is to throw it away. 

How long does weed stay good in a plastic bag?

If you’re wondering how long does weed stay good in a plastic bag, then the answer is not long at all. Plastic bags are a terrible place to store weed because they’re open to the air and won’t seal up well. That can let moisture in and stimulate the growth of mold. 

How long does weed stay good in a plastic bag_

How long does weed stay good in a jar?

When considering how long does weed stay good in a jar, you’ll be pleased to discover that it should keep for up to half a year. But the jar needs to be kept closed and sealed the whole time. That blocks any moisture from getting in. Then all you need to do is put that jar in a location that’s dry and cool. 


Hopefully, this article has put you off the idea of smoking weed that isn’t fresh. If you’re desperate for a hit or you’ve found some old weed, it’s best not to let temptation get the better of you. You might end up very ill if you do, and it’s best to throw away that old weed and get some new weed.  

Click here to get fresh marijuana seeds from I Love Growing Marijuana.

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