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?

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.
Humidity
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.

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

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

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.
Mold
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.
Mold-resistant Strains
Purple Kush Autoflower
Plant Type | 100% Indica |
THC | Up to 22% |
CBD | Insignificant amounts |
Grow Difficulty | Moderate |
Climate | Indoors | Mold Resistant | Continental |
Plant Size | Compact |
Flowering Time | 8 weeks |
Yields | 4 to 6 oz per 3x3ft |

Blue Cheese Feminized
Plant Type | 80% Indica 20% Sativa |
THC | Up to 19% |
CBD | Insignificant amount |
Grow Difficulty | Easy |
Climate | Indoors | Continental | Mold Resistant |
Plant Size | Average |
Flowering Time | 8 weeks |
Yields | 5 to 9 oz per 3x3ft |

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Plant Type | 20% Indica 80% Sativa |
THC | Up to 22% |
CBD | Insignificant amounts |
Grow Difficulty | Moderate |
Climate | Indoors | Mediterranean | Mold Resistant |
Plant Size | Tall |
Flowering Time | 9 weeks |
Yields | 21 to 25 oz per 3x3ft |

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Texture
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.
Scent
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 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.
Conclusion
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.
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