Does Weed Go Bad?

Weed doesn’t go bad the way a jar of mayo or some other food product might, but it can definitely be “off” or even moldy.

Old weed likely won’t lead to any serious health issues if you don’t have any underlying conditions.

It can, however, have a noticeable drop in potency, which can be a big deal if you’re using it for medical purposes. Older weed can also undergo changes in taste and texture.

How long does it stay fresh?

When stored properly (more on this later), dried cannabis keeps for 6 months to 1 year. Over time, it begins to lose its aroma and potency.

According to some older research, weed loses roughly 16 percent of its THC after 1 year, and it just keeps dropping from there:

  • 26 percent THC lost after 2 years
  • 34 percent THC lost after 3 years
  • 41 percent THC lost after 4 years

Effects of Stale Weed

So, although weed may slowly lose some of its potency over long periods of time, it will never “expire” the same way groceries do. But that doesn’t mean that you should let your weed go stale. Besides the biggest detriment of losing potency over time, weed will also slowly lose its aroma, texture and flavor over time.

In the most extreme cases, you will be left with nothing more than a stash of impotent, crumbly dust that isn’t usable for anything.

So, Does Weed Go Bad?

Does weed go bad? How to tell if your stash is stale

Yes, weed goes bad. In fact, there are a couple different ways it can go bad. On one hand, if your weed sits unused for too long, or you leave it exposed to too much light or open air, it will simply dry out and turn into dusty, crumbly, ineffective flower. On the other hand, if your weed is exposed to too much humidity or other contaminants it could go moldy. And you do not want to inhale mold smoke. Doing so can make you sick.

Beyond the possibility of getting sick from bad weed, keeping your weed fresh will give you a better product and a better cannabis experience. The longer cannabis is exposed to environmental factors such as light and air, the more the cannabinoids and terpenes deteriorate. So if you want weed that will taste and smell great, while getting you super high, take care of your bud the right way.

What About Old Edibles?

Things change when discussing old cannabis edibles. While the THC content gradually degrades in CBN, which isn’t harmful, the other ingredients in edibles, such as eggs and milk, WILL go off.

If you are worried about an expiration date found on a purchased edible, it is probably a good idea to bin it. At best, it won’t make you sick but will taste like ass. If you make your edibles, store excess portions in the freezer.

Airtight Storage

One weed lover/scientist decided to find out exactly what happens to cannabis as it ages and sent a five-year-old sample into the Cannalysis testing lab. We already know that THC transforms into CBN when exposed to oxygen. CBN is known for its exceptional healing properties and is also a very effective sleep aid according to users. The sample in question was kept in a glass mason jar, so exposure to air was minimal. As a result, the weed’s THC content remained high, although the percentage of CBN also increased slightly.

In terms of aesthetics, the buds were less resplendent in terms of glimmer and color. When the buds were new, they were sticky, but after five years of airtight storage, they had become crunchier, although the trichomes were still in excellent condition. Rather surprisingly, the terpene content and scent remained strong, although the first whiff of the weed after opening the jar was awful!

The marijuana also had a different taste, with a dry and earthy flavor and a relatively harsh throat hit. Overall, weed that has been stored in an airtight container will still provide you with a decent experience after several years.

Improperly Stored

Depending on where the weed was stored, the bud will become damper or drier with age and will have an extremely high CBN count. If the weed is dry when you find it, you can safely smoke it, although you should prepare for very harsh hits. If the weed is damp, there is a chance it will develop mold, and trying to smoke moldy marijuana IS a health hazard. Incidentally, while the oldest known marijuana stash contained a high level of CBN, the 2,700-year-old sample still contained a reasonable amount of THC; enough to get a novice user high at the very least!

A bigger problem is if your old marijuana has been exposed to damp conditions. Weed can develop mold during the growing cycle, or if it has been stored with an excessive level of moisture in it. Regardless of how it happens, using moldy cannabis is a health hazard. Use a magnifying glass to check any bud you suspect of being moldy. The mold itself resembles a dense cobweb and usually has a gray coloring.

An alternative is to shine a black light on the bud. Any mold on it will have an obvious green hue. Smoking mold means inhaling thousands of toxic spores, which can cause serious respiratory problems. Regardless of its age, dump any moldy marijuana you find.

Identifying Old Weed That May Be Past Its ‘Best Use’ Date

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In summation, marijuana stored in an airtight container away from direct heat and also not kept in a damp location can last many years and remain perfectly usable. However, the weed you purchase isn’t always necessarily kept in such pristine conditions, so you have to know when someone is trying to sell you bad marijuana. Alternatively, if you find old weed and don’t know how long it has been hidden, you need to check these pointers to ensure you’re not using stale cannabis that is certain to have a nasty taste.


Excessively old and dried out weed will break apart into a fine powder with ease. While it may initially resemble kief, stale marijuana may also contain seeds and stems. You can identify mold fairly easily once you know what to look for. Check out the location of the offending substance’s concentration to determine whether it is mold or trichomes: Mold grows over trichomes and looks like a mass of white powder capable of penetrating every surface of the herb. You can also spot mold when you break apart the nugs.


Terpenes don’t last long on poorly stored weed. Therefore, if your cannabis offers a pleasant scent, it is almost certainly fit for consumption. Beware marijuana with a mildew-type smell, as this is a sign of possible mold growth. If you get a weird chemical aroma, it probably means that pesticides or other chemicals have been used to treat the weed while it grew.


Pulling apart the nugs should tell you everything you need to know about the condition of the weed. You can determine whether there is any moisture content or see if it falls apart in your hands. Herb that is well cured and dried will make a ‘snapping’ sound when you handle it, whereas old cannabis makes a cracking sound and also feels extremely dry.


If your marijuana passes all of the above tests, smoke a small amount to be 100% sure. One thing about ‘bad weed’ is that you will taste the problem almost immediately!

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