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Does marijuana expire? While marijuana is not perishable like food products, weed’s potency, aroma, and taste can reduce, and the risk of mold can increase. Our guide covers the factors that can affect cannabis shelf life, how to tell when cannabis is bad, and how to properly store weed for short-term or long-term storage. 

Factors That Affect Cannabis Shelf Life

Keeping your weed fresh and potent is easy and affordable, as long as you keep it in a cool, dry, and dark location to preserve freshness. When it comes to cannabis flower, there are a few factors that can quicken the natural degradation process.


Excessive heat can dry out your cannabis flower faster than you'd like. If left under the hot sun for a prolonged period of time, cannabis’ aromatic terpene compounds can evaporate, leading to a reduced aroma and harsh smoke.


Too much moisture when storing weed can increase the risk of developing moldy weed, especially when it's hot out. Reaching above the recommended relative humidity (RH) can produce mold while going under the range can dry out the weed.


Natural and artificial sunlight can degrade the plant's chemical composition. In THC-rich cannabis, direct sunlight exposure and other environmental fluctuations can accelerate the THC-to-CBN conversion process. As THC converts to cannabinol (CBN), you lose potency in your weed. CBN has a much weaker potency than THC.

How Long Does Cannabis Last?

Properly stored dried cannabis can stay good for six months to 1 year. Research on cannabis shelf-life indicates that cannabis can lose about 16% THC after one year, 26% after two years, 34% after three years, and 41% after four years. 

Medical marijuana users who need strong and potent relief and recreational users who want the best cannabis experience must use best storage practices to maintain the potency and freshness of cannabis flowers, cannabis oils, and other cannabis products.

Is My Cannabis Old?

How do you know if your weed has gone bad? Do you have potent weed, or has it lost all its potency? In many cases, old weed may still be good to use, although it may have a subtle aroma or no aroma.

Here are a few ways to determine the quality of your cannabis.


Older weed can have a brittle, dry, and dull appearance compared to fresh weed. Consider its color, trichome density, and texture. If it crumbles between your fingers or it's too spongy and moist, it's way past its prime.


As weed ages, its smell goes with it too. Old cannabis can smell like nothing or musty and hay-like if it’s moldy. Use your nose to compare its smell against how it smelled when you first got it. Old cannabis can be harsh to smoke.


Old weed is relatively safe to consume for most users but can have a different chemical profile compared to its peak freshness. Old weed can have a higher concentration of cannabinol (CBN), a byproduct of THC, and fewer terpenes. The “entourage effect” where all components work together and the overall potency of the product may be reduced.

How to Check for Moldy Cannabis

While weed does not have an expiration date, it can develop mold. A thorough mold inspection is critical to ensuring your product is safe to consume. Mold isn't easily visible but can appear as a small white powder or fuzz.

Moldy weed can have a musty or hay-like aroma that smells nothing like most fresh cannabis flower. Mold inspections are essential not just for old weed but also for any weed you buy. A 2017 study found mold and bacteria in 20 samples from licensed dispensaries and grow facilities in Northern California.

If consumed, mold may not produce severe effects, although it can increase the risk for nausea, vomiting, and coughing, especially for those with respiratory conditions and compromised immune systems.

How to Store Cannabis

How do you keep weed fresh for longer? Best storage practices for cannabis products differ by product type. Here is a rundown of the best ways to keep each cannabis product fresh and potent.


Cannabis flower needs to be away from light, air, and in an optimal relative humidity, between 54% and 63%. Store your cannabis in a glass jar that has an airtight seal and is preferably opaque to protect it from the UV rays. Avoid opening and closing the glass jar and storing it in a cool, dry, and dark place.

For cannabis connoisseurs who want to keep their weed fresh, they can use a humidity control pack, such as ones from Boveda, that absorb and release moisture as needed. Cannabis humidors may also provide an extra layer of protection.


Cannabis concentrates such as cannabis oil and extracts (shatter, wax, crumble, etc.) can remain fresh and stored in small containers designed for cannabis extracts made out of glass or silicone. Ensure the container lids are tightly sealed and keep your dabs in a cool, and dark place.


Cannabis edibles should be kept in their original packaging and stored away from direct light, in the open air, or under high heat. Some edibles, such as gummies and hard candies can melt in hot temperatures.

Vape Cartridges and Pens

Vape cartridges and pens should be kept away from direct light to reduce their potency. Ideally, you should store your vape pen standing upright to keep the oil at the bottom of the cartridge and be ready for immediate use. 

Freezing Cannabis

Storing cannabis in the freezer can be suitable for long-term storage. However, freezing temperatures can make the trichome glands brittle and easy to break off with the slightest movement. If storing cannabis in the freezer, avoid handling the material or gently handling it and allow some time to thaw before use.

Vacuum sealing can help preserve trichomes but can compress your buds. If you want to remove air from a container, you can inject carbon dioxide or nitrogen into the container. The container must have two holes, one where the gas can be injected, and another where the ambient air leaves, and then seal the holes.

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Shoulderless containers are recommended over shouldered containers since they are not prone to developing cracks.

For best results, pack just enough weed for short-term use (about a week) and leave the rest of the frozen or stored material undisturbed. This helps preserve the freshness of your stash for longer than opening the lid too often.

Learn How to Grow Weed and Keep It Fresh at CTU

Preserving cannabis freshness takes care and knowledge. Earn that knowledge to be a better cannabis user, grower, cook, employee, or business owner by enrolling in Cannabis Training University's cannabis certification program. Learn online, at your own pace, and on your own schedule. Become a cannabis growing expert today! 

Fred Hernandez - Cannabis industry expert writer
Fred Hernandez

Fred Hernandez is a highly accomplished and versatile writer, boasting an extensive background in the cannabis industry. With an in-depth understanding of various sectors including cultivators, processors, retailers, and brands, Fred's expertise spans across the entire cannabis landscape. As a prominent contributor to CTU, he consistently delivers insightful articles exploring the latest developments, news, and regulations shaping the cannabis industry. Whether it's delving into the intricacies of cannabis products, cannabis strain reviews, or providing comprehensive analyses of cannabis laws, or sharing expert insights on cannabis cultivation techniques, Fred's wealth of knowledge positions him as an invaluable writer and educator for all cannabis-related subjects.

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