Does Weed Go Bad? Here’s How You Can Tell

In a word, “Yes.” As cannabis is an organic, living plant, it can expire in many stages, from growing to the final product. During the cannabis growth cycle, farmers must check for mold, mildew, pests, nutritional deficiencies, bud rot, and many other issues. Then, once the final product is made (flowers, concentrates, etc.), it must be tested for chemicals and pathogens (bacteria, spores, etc.). Just like with standard house plants, ensuring that the plant has a healthy root system is also of utmost importance. Knowing what you’re getting and ensuring what you buy is high-quality is extremely important for a medical marijuana patient.

Table of Contents
  1. The Importance of Curing
  2. Tips for Cannabis Storage
  3. How Long Does Cannabis Keep Fresh For, and How Long is it Usable For?
  4. Does Weed Get Old?
  5. How Long Do Concentrates Keep For? Does Hash Go Moldy?
  6. Can I Smoke or Salvage Moldy Weed?
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The Importance of Curing

Cannabis flowers must be properly dried and cured, not only to produce a more pleasant experience, but also to prevent the cannabis from going moldy. “Curing” means leaving the cannabis bud in an airtight jar and “burping” the jar every so often. Doing so will break down the sugars and chlorophyll within the plant properly and improve the flavor of the product as the terpenes become more pronounced over time. Letting out the air periodically will also prevent moisture from getting trapped in the jar and growing mold on the plant.

Tips for Cannabis Storage

Cannabis buds are more prone to going bad over time, especially if they’re not properly stored. Concentrates may last a little longer, but they may have some plant matter left over in the final product, meaning certain types of hashish or concentrate may also go bad over time. Putting your buds and concentrates in airtight containers will help keep them fresh for a little longer, but the cannabis will slowly lose potency, often after reaching a peak curing time, similarly to wine.

What Moldy Weed/Marijuana/Cannabis Looks Like
What does mold on weed look like? Source 

Avoid Hot and Humid Environments

Exposure to sunlight and air will also affect how long cannabis will last. Hot, humid environments are particularly bad for food of any kind, so it’s no surprise that cannabis (which is a plant, after all) is more prone to mold and mildew in such environments. Many people also take to vacuum-sealing and freezing their cannabis buds in order to cure their bud properly, especially if they live in hot and humid places.

Use Airtight Containers

The best way to store weed is in dry, airtight containers, such as a mason jar with a clean lid. Some growers even use humidity packs to keep dried cannabis buds, regardless of the environment the grower lives in. Whether you are a grower or not, mason jars are a good buy for those wanting to keep their cannabis in the best condition possible.

Some people store their marijuana buds in plastic baggies, but this is problematic for two reasons:

  1. The little fuzzy plant hairs on buds, called trichomes, fall off due to static. Trichomes are important for the flavor, potency, and smell of cannabis buds, so you want to preserve them as much as possible.
  2. Plastic baggies make the bud “sweat” and smell (and not in the way you want). Sweat leads to excess moisture in the storage container, and as we just established, that can make your cannabis moldy.

Keeping larger amounts in mason jars (or smaller amounts in small mason jars) avoids such drawbacks, as well as allows you to carry on the curing process! However, any moisture trapped in a mason jar can have the same effect and encourage mold growth, so it’s best to keep cannabis only in mason jars that are cleaned often and properly dried.

How Long Does Cannabis Keep Fresh For, and How Long is it Usable For?

Assuming it’s being kept properly, most cannabis plants will cure and peak for about 3-6 months. After that, it will start to lose potency, and its THC (formally known as tetrahydrocannabinol) will slowly degrade into the cannabinoid, cannabinol (CBN). CBN tends to produce little psychoactive effect, but may help induce sleep and relaxation. In fact, some people purposefully store their cannabis for longer periods in order to adjust the ratio of THC to CBD to produce different effects.

Does Weed Get Old?

Once harvested from the plant, properly kept cannabis will generally keep for about a year, but will generally start to lose potency at the 6-8 month mark. Assuming it hasn’t gone moldy after 12 months and has been kept in an airtight container, cannabis will be usable for 18 months to 2 years, though its effects won’t be as strong.

Uses for Old Weed

Many people use older cannabis to make oils and butters to keep their produce going for a little longer and increase the potency. As previously mentioned, the THC in older cannabis degrades to CBN – which can be used to help get to sleep. If you have old weed that hasn’t molded, try making your own cannabutter with it for a healthy sleep aid. This can especially be useful for those who struggle with insomnia.

How Long Do Concentrates Keep For? Does Hash Go Moldy?

Hashes, tinctures, and concentrates should also be kept in an airtight container out of direct sunlight. Most hashes, tinctures, and concentrates that are well-made and stored properly will stay fresh and usable for around five years. However, different types of hashes will keep for different amounts of time, depending on how much plant matter it contains, how tightly pressed it is, and how long it gets “knocked around” for (remember, those trichomes are important!).

How the Hash Production Method Affects Lifespan

The production method used to make a hash or other concentrate also makes a difference, as some methods make a purer product than others. Concentrates, waxes, and hash oils made using supercritical carbon dioxide (not solvents – they can leave nasty impurities in the final product) will, therefore, last longer than hash made from traditional methods like ice extraction, pressing, bubble bags, etc.

Hash made using these traditional methods may generally keep for a little longer than buds if kept well – about 2-2.5 years – but will start to lose potency after around 6 months. Purer methods of hash-making, which strip the cannabinoids away from plant material, will keep for around 3-5 years, although potency will still reduce after 6 months or so. That’s because more of the organic material that can mold or rot is removed from the final product. Some people use moldy hash and buds to make purified oils, as these methods can remove mold in their manufacturing process. Since hash, oils, and other concentrates do not need to be cured like buds need to be, they will be most potent within the first month of making it.

However, hash and concentrates made from properly cured marijuana buds tend to produce better results (because less water from the buds goes into the mix and therefore, isn’t as diluted), and many report a better experience by leaving hash to cure for about a month or two, especially if using bubble method. Doing so will help keep your hash potent and pathogen-free for quite some time.

Cannabis with White Mold
White mold on cannabis. Source 

Can I Smoke or Salvage Moldy Weed?

If you find mold anywhere on your cannabis, throw it away – the health risks just aren’t worth it. If you recently bought something from the dispensary and find there’s mold on it, take it back and complain. Dispensaries are responsible for selling a quality product and you should be able to get refunded for any products that are defective or were improperly stored. Ensuring you get the best out of your medicine is of the utmost importance, and will save you not only money, but also your health.

There are some who may suggest making moldy cannabis into butane hash oil (BHO), but this is not recommended either, as mold can still enter the final product. Breathing in mold is extremely dangerous and you do not want even a small amount to get into your lungs. This is even more important if you have an allergy or are immunocompromised in any way.

Conversely, if you find a small amount of powdery mildew on your marijuana plants, you can safely get rid of it. One of Leafwell’s favorite growers, Jorge Cervantes, shows us how to do so here:


Like any other medicine, marijuana needs to be properly stored and consumed in a reasonable timeframe in order to keep its potency. In every stage of its life, the marijuana plant needs to be carefully cleaned, cured, and taken care of. If you grow cannabis, you’ll want to ensure you cure your product properly, as it will last longer.

Store your cannabis in an airtight container away from sunlight and humidity. If you don’t have mason jars already, invest in a few to help preserve your medical marijuana. Once you get them, remember to clean them regularly and make sure they’re completely dry before using them for storage. If you find mold on your buds, throw it away immediately to avoid breathing in dangerous toxins.

Lastly, if you find your cannabis frequently molds before you use it, consider switching to hashes or concentrates, which have a longer shelflife than cannabis flower. All cannabis products, and especially buds and hash, should be regularly checked for mold and mildew. Dispensaries should be doing this all the time, and so should you once you get your products home.

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Written by
Dipak Hemraj
Dipak Hemraj

Dipak Hemraj is a published author, grower, product maker, and Leafwell’s resident cannabis expert. From botany & horticulture to culture & economics, he wishes to help educate the public on why cannabis is medicine (or a “pharmacy in a plant”) and how it can be used to treat a plethora of health problems. Dipak wants to unlock the power of the plant, and see if there are specific cannabinoid-terpene-flavonoid profiles suitable for different conditions.

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