Can weed expire? How to detect whether weed is too dry or moldy

Can weed expire? How to detect whether weed is too dry or moldy
Max Sargent

Did you ever stumbled across an old batch of weed and wondered whether it's still good to smoke? 

Did you ever stumbled across an old batch of weed and wondered whether it's still good to smoke? Let's take an in depth look at dry and/or mouldy weed. We’ll answer the common question of whether weed can go off, and also show you how to check whether your stash is still smokeable.

Unless you’re exposing your stash to extremely tough conditions, you can be pretty sure that you’re weed won’t go off.

Weed can technically go mouldy when exposed to extreme levels of humidity. However, the weed you buy from a dispensary (if you’re lucky enough to live in an area where sales have been legalized) is usually professionally grown and cured, which means it’ll be dry enough to avoid this problem.

Even if you’re buying marijuana legally, as long as you’re using a decent, reliable dealer, the weed you’re getting should be cured to similar standards. However, it’s not unheard of for people to get their hands on new batches affected by mold, so be sure you only buy off a dealer you know or trust.

If you’re buying brick weed, be extra careful. This kind of cannabis is usually pressed when slightly moist and, if not cured and stored properly, can be mouldy by the time you get on your hands on it.

However, unless you’re purposefully exposing your weed to extreme levels of humidity, you shouldn’t be concerned about it going off. If you’re worried about your weed going off, check out the cannabis storage tips at the end of this article.


Yes, weed can become old and stale when not stored correctly. Air and direct sunlight will make weed dry and stale really quickly, which is why it is recommended to keep your stash in a container in a cool, dark place (more details below). Heat, on the other hand, has a much more complicated effect on cannabis.

As cannabis grows, it produces a substance called cannabigerolic acid (CBGA) which is then synthesized into one of three major cannabinoids: CBDA, CBCA and THCA. Through a process called decarboxylation (a fancy word for heating), these cannabinoids turn into CBD, CBC and, of course THC.

When exposed to extreme levels of heat and light for prolonged periods of time, THC may actually transform into CBNA, which will later convert into CBN when smoker or vaporized. CBN, or cannabinol, is a cannabinoid that has been shown to relieve pain, curb insomnia, promote bone growth and, most notably, be a very strong sedative.

According to Steep Hill Labs, a cannabis testing laboratory, 5mg of CBN is as effective as 10mg dose of diazepam, a mild pharmaceutical sedative.[1] Unlike THC, CBN is non-psychoactive, meaning it won’t get you “high” which, depending on why you use marijuana, may be a good or a bad thing.

So,  exposing your stash to extreme heat and light conditions for prolonged periods of time may leave you with a very sedative batch of weed. However, we believe it's very unlikely anyone is able to expose their weed to such conditions without purposefully manipulating the light/heat conditions in their house.



In optimal conditions, weed can keep for years. Even if you pay no attention to how you store your weed, chances are it’ll keep well for at least a month. Like we saw above, as long as you’re not storing your weed in an extremely humid area in direct sunlight, you should be fine.


Depending on how picky you are about your smoke, if you tumble across an old batch of weed, you may want to check whether it’s still worth smoking (or vaping or eating). Here are some simple tips on how to check whether your weed is still good:


Terpenes are usually the first cannabis compounds that are affected by storage. Terpenes are very fragile and, if they start to disappear, will affect the aromatic profile of your weed. To see whether you’re weed still contains a decent concentration of terpenes, open up your stash and smell it. The aroma you get should be nothing short of pungent and intense.

If you’ve bought a strain with distinct aromatic notes (like any CheeseDiesel or lemon strain, for example), check to see that those aromas are still detectable.

If not, it doesn’t necessarily mean you shouldn’t smoke it; however, you might want to look into some alternative storage methods to help you preserve the terpenes in your weed for longer.

However, if you detect any musty, mildew-like smells, you may want to proceed with caution; these are tell tale signs of mold.


Once you’ve smelt you’re weed, take it out of its container and inspect it visually. You may want to use a magnifying glass to take a closer look at your buds and see whether they’re still “smokeable.”

Old, dry cannabis will become brittle and generally breaks apart into a fine powder with minimal effort. If you see excess amounts of fine powder at the bottom off the container where you store your stash, that’s a pretty decent sign it’s too dry and will be harsh to smoke.

By looking at your weed you’re also able to detect mould. Mould will generally form as a fine white powder that covers every nook and cranny of your buds. If you’re worried about mould, use your magnifying glass to take a closer look at your weed and look for a powdery mass forming on top of the trichomes.

If you struggle to distinguish between trichomes and mould, you may want to break apart your nuggets.


Cannabis provides a variety of tactile cues that can help you decide whether it’s still worth smoking. Healthy buds shouldn’t be overly moist and shouldn’t break apart easily. If your stored buds are wet or moist, you may be storing them in too humid conditions. On the other hand, dry buds will be, well, dry to the touch, brittle, and easy to break apart.

If you’re worried about a mould that you weren’t able to detect by smelling or visually inspecting your weed, try to break apart some of your buds. If you find a white powder has penetrated the inside of your nuggets, throw them out.


Finally, if you’ve smelt, touched, and looked at your weed and everything seems fine, give it a taste. Either pack a little bit of it into a pipe or vaporizer and take a small toke. If it tastes good, you’re good to go.


  1. ^ Steep Hill, Cannabinol (CBN): A Sleeping Synergy, retrieved December-06-2018

Max Sargent
Max Sargent

Max has been writing about cannabis and psychedelics for several years now. With a strong belief that an open, honest attitude toward drugs and drug policy can improve the lives of many, he seeks to offer insightful and developed opinions on the subject.