How to keep weed fresh
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- Moisture and mold in marijuana
- The best temperature to store your cannabis
- Light and oxygen change cannabis composition
- Extending the shelf life of weed
- Frequently asked questions
Over the years, cannabis packaging in legal or medical marijuana regions has become more sophisticated, with features designed to maintain freshness. The packaging on your marijuana products might have a harvest date on them, but flower doesn’t come with an expiration date. So even with producers improving their packaging, you might find yourself wondering: how long does weed stay fresh?
About the two worst ways you can store your bud are on a tray, exposed to oxygen and light, and in a plastic sandwich bag, just like a dealer’s bags that are common on the illicit market. A number of environmental factors affect how well the plant grows, but cannabis storage is also a key component of quality and freshness. Cannabis needs the right balance of conditions to remain fresh.
Cultivators go to great lengths to ensure your flower is packaged with optimal moisture content, usually in opaque packaging to keep light out. You’re probably wondering why you still see transparent and clear containers lining your dispensary’s shelves.
Well, old habits die hard and the practice of seeing and smelling the product on the shelf is still a key component for many people when it comes to deciding what to purchase. Some companies have even started replacing the oxygen in their packaged flowers with nitrogen to help maintain freshness.
For the best possible marijuana experience, you need to know how to keep weed fresh and how to store weed properly. This guide will give you everything you need to know.
Moisture and mold in marijuana
Moisture and water make a big difference when it comes to degrading the shelf life of cannabis.
While no two cultivators dry their flowers in the same way, all cultivators dry their flowers and then put them through a process called curing.
When cannabis is properly cured, it allows the moisture that is trapped inside the bud to slowly dissipate from the flower without changing any of the cannabinoids or losing terpenes. Once the flower has the perfect moisture content, usually between 6% and 9%, it is placed into packaging from which excess oxygen has been removed. When you take it home, it’s important to try to maintain that balance.
Once the flower has the perfect moisture content, it is placed into packaging from which excess oxygen has been removed. When you take it home, it’s important to try to maintain that balance. Photo by: Gina Coleman/Weedmaps
If you lose too much moisture, it can change the integrity of your flower. Your flower will become brittle and lose essential terpenes that affect potency and taste. On the other hand, with too much moisture or water, the consequences are more serious. So serious, in fact, that the American Society for Testing and Materials (ASTM), which develops technical standards across many industries, published the “Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower” in May 2018.
The ATSM defines water activity as “the (quantitative) capability of the cannabis flower in a sealed container to affect the humidity of the container’s headspace air.” Headspace is the air that surrounds the flower. Water activity measures vapor pressure against pure water. If water activity is 0.55, it is 55 percent of water.
During storage, water activity cannabis should remain within a range of a minimum of 0.55 and a maximum of 0.65. Water activity increases with temperature, which is why light and temperature control go hand-in-hand as best practices for how to keep weed fresh.
The relationship between moisture content and water activity is complicated, and the cannabis industry is still striving to determine the optimal moisture content for packaged flower.
What we know now is that a relative humidity level anywhere above 65% can significantly increase the likelihood that your weed will end up growing mold. According to the American Herbal Products Association, the drying process will dehydrate cannabis until it has a moisture content of less than 15%, and the curing process is where the remaining moisture is slowly removed to retain the volatile oils.
The best temperature to store your cannabis
To extend the shelf life of marijuana, it should be kept in a cool, dark place at or slightly below room temperature. The ideal temperature to store your weed is below 70 degrees Fahrenheit, or 21 degrees Celsius.
High temperatures combined with high moisture activity and relative humidity can lead to mold and mildew. Mold thrives between 32 and 120 degrees Fahrenheit, or 0 to 49 degrees Celsius, and growth is most active between 70 and 90 degrees Fahrenheit, or 21 to 32 degrees Celsius.
High temperatures and arid environments dry out your flower and evaporate sensitive terpenes, which ultimately change the effects and taste of the flower. This is why some cultivators skip drying and make live resin extracts to preserve all the monoterpenes that are lost during the drying process.
Lower temperatures are not as problematic, but they can make it harder for tetrahydrocannabinolic acid (THCA) to decarboxylate into tetrahydrocannabinol (THC). Lower temperatures will reduce the potency of the flowers when they are smoked or could make the trichomes brittle on the plant, causing them to break off when they are removed from the cold environment.
Light and oxygen change cannabis composition
Exposure to light is the biggest culprit when it comes to aging weed. This has been known since at least 1976, when a study published in the journal Pharmacy and Pharmacology explored what happens to the stability of cannabis under various conditions. It concluded that light is the single largest contributor to loss and deterioration of cannabinoids and suggested that “carefully prepared herbal or resin cannabis or extracts are reasonably stable for 1 to 2 years if stored in the dark at room temperature.”
Ultraviolet (UV) light will always degrade your weed, even if you store it safely in glass jars. So, while the clear glass Mason jars you see in the marketplace look nice, they won’t protect your purchase the way an opaque container will. If you really like to look at your marijuana, a brown container will filter out visible ultraviolet light — that’s why brewers use them to bottle beer. Meanwhile, green containers will block out roughly 30 percent of UV rays.
As time goes by, prolonged exposure to light and air will gradually convert THCA into THC. At the same time this is occurring, existing THC is being converted into cannabinol (CBN), a cannabinoid that does not create the intoxicating properties that THC delivers.
Ultraviolet (UV) light will always degrade your weed, even if you store it safely in glass jars. Photo by: Gina Coleman/Weedmaps
And it’s not just THC that’s affected. Cannabidiolic acid (CBDA) can transform into cannabidiol (CBD) with enough exposure, and THCV will degrade into CBV. During this time, your weed could potentially become less potent.
In addition to playing a role in the conversion of cannabinoids, oxygen can also oxidize essential terpenes and change the overall aroma of the flower into a grassy, haylike smell.
To reduce exposure to oxygen, make sure there aren’t many air pockets in your container. You should always store your weed in an airtight container. Don’t use very large containers to store small quantities of weed, as this leaves too much air inside the container with your herb.
Of course, it is inevitable that some amount of oxygen will get into your sealed package once it is open, but you can limit the amount of time that the jar is opened and the number of times it is opened.
If you store your weed in sealed bags, remove as much air as possible before sealing. Vacuum-sealing weed can be a reliable, long-term storage solution for your stash. If you go this route, be sure you follow these tips to avoid inadvertently damaging your weed:
- Try to avoid vacuum sealing your marijuana in plastic that contains bisphenol A (BPA). This chemical is a key ingredient in many types of plastic, but it has proven to be harmful to humans. And unfortunately, if you store your weed in plastic containing BPA, some of those dangerous chemicals could leach into your marijuana.
- Handle your weed delicately. Plastic easily builds up static charges that can pull trichomes off your buds. Trichomes are the cannabinoid- and terpene-rich hairlike glands all over cannabis flowers, so you’ll want to avoid damaging them.
If you plan on storing your vacuum-sealed weed in the freezer, know that freezing will also make your trichomes vulnerable to damage, as they will become brittle.
Extending the shelf life of weed
Knowing how to store weed properly will help you get the most out of your cannabis experience. Ultimately, the key to extending marijuana shelf life is all about limiting exposure to the elements. When it’s time to open your container, pull out your flower and immediately close your package. Don’t let it sit open, and avoid windy or highly ventilated areas.
To maintain the right level of moisture, use a salt-based control sachet to maintain the ideal relative humidity. According to the ASTM standards (D8197-18), “a salt-based control sachet designed to maintain a relative humidity of 0.55 to 0.65 in a sealed container can be used to maintain optimum storage conditions.”
Additionally, you can store your marijuana in a cannabis humidor box, which has been designed to maintain the ideal humidity for marijuana. There are currently several models available on the market.
Whatever you do, be sure you don’t use a cigar humidor to store your weed. Cigar humidors are typically lined with cedar wood. The oils in the wood help enhance the taste of cigars, but those same oils tend to harm cannabis. Similarly, humidors for cigars often use sponges or propylene glycol to create humidity that are ideal for tobacco, but are much too high for cannabis.
In the past, to remedy dry weed, people would add an orange peel to their bags to keep the moisture content, but this greatly increases the likelihood that mold would be introduced. In addition, the water activity of orange peels is unknown and the aroma of the peel could alter the flavor and aroma of your weed.
Nowadays, you can use the same humidity control packs, such as Boveda packs, to reintroduce moisture if it is too dehydrated. This will not reintroduce terpenes that were lost, but it will ensure that you don’t have a harsh smoking experience.
To keep your weed in tip-top shape as long as possible, take careful steps to avoid exposure to light, moisture, oxygen, and extreme temperatures. Photo by: Gina Coleman/Weedmaps
Like almost everything else, weed doesn’t last forever. Over time, changes to the molecular structure occur with exposure to heat, light, and moisture.
When cannabinoids and terpenes experience very high or very low temperatures, dry up, are exposed to too much moisture, or are left in the presence of light, chemical changes that will degrade the potency of the flower and could alter the taste and mouthfeel may occur.
As terpenes are exposed to environmental changes, they can oxidize or evaporate, creating a change in aroma and effects. And even though all weed degrades over time, the process can be slowed down if you control the temperature, moisture, and the amount of oxygen your flower is exposed to. To keep your weed in tip-top shape as long as possible, keep an eye on the harvest date on the packaging and take careful steps to avoid exposure to light, moisture, oxygen, and extreme temperatures.
Frequently asked questions
What’s the best smell-proof container for weed?
The simplest way to keep your stash smell proof is to make sure it’s stored in a solid airtight container with a sealable top. Sealable glass jars, like a Mason jar, are typically sufficient for storing your stash and keeping in the smell. Some cannabis consumers also use large medicine bottles to keep their stash from stinking up their living space. Online retailers also offer a variety of odor-proof containers designed specifically for weed storage.
Is refrigerating or freezing weed bad?
Refrigerating or freezing weed is definitely preferable to storing it in an area that’s too hot or humid. And though some cannabis consumers report successful long term weed storage through freezing, it’s more than possible to lose freshness and potency to icy temperatures, as trichomes may become brittle and break off more easily. Storing your stash in an opaque, sealed container, in a relatively cool place with minimal sunlight is your best bet for long term storage with minimal degradation.
How to keep weed fresh Copy article link to clipboard. Link copied to clipboard. Contents Moisture and mold in marijuana The best temperature to store your cannabis Light
How to Re-Hydrate Dry Cannabis Buds
As you reach the bottom of your cannabis stash, you’ve probably noticed that your buds have gradually dried out. Preventing dry-out and keeping your cannabis at the ideal moisture level has a few benefits:
- The smoke/vapor is more palatable and a bit cooler
- Ground cannabis is easier to manipulate and roll into joints
- Better preserved flavor and potency
Naturally, the best way to prevent your cannabis from drying out is to take care of it in the first place, so let’s first go over some of the best preventative techniques for keeping your green fresher, longer.
Preventing Dry Cannabis
With these two easy precautions, you can extend the shelf life of your cannabis significantly.
Air-Tight, Away From Light
UV rays and oxygen are the enemies of fresh cannabis. Sure, sunlight and oxygen were this plant’s best friends before it came off the stalk, but once the cannabis is dried, cured, and packaged, you want to limit its exposure to the elements as much as possible.
For people buying cannabis in bulk (i.e. 1/4 oz. or more), it’s prudent to portion out your cannabis to keep each pack at peak freshness instead of cracking open the same jar every time, exposing those fresh nugs to the unforgiving composition of your local atmosphere. Think ahead and keep your greens fresh!
Glass Jars Over Plastic Bags
A flat of tiny, air-tight jars only costs about $10, and glass storage make a world of difference when it comes to keeping cannabis fresh. These don’t have to be anything fancier than a mason jar, but you can obviously find some pretty slick containers to house your stash.
A plastic bag will work in a pinch or if you have nothing else. Just be sure to remove as much air as possible from the bag before sealing. My preferred method is to roll the bag up from the bottom—like a rolled taco or crepe—toward the seal.
These simple techniques will keep your fresh bud fresher, but what if you get a dry bag of herb or you stumble across an old stash?
How to Re-Hydrate Dry Cannabis Buds
Re-hydrating your cannabis is a delicate process that requires patience, but not much more. Here are a few methods that I’ve used and have gathered from cannabis aficionados around the web.
Distilled Water Method
Distilled water is not that different from other water, but it is an extremely important ingredient when re-hydrating your cannabis. Distilled water, unlike tap water, has been evaporated and recollected to remove impurities. This chemically pure water is also used in some humidors.
Whether your cannabis came in a jar, Mylar bag, or a medicine bottle, this method will work about the same for each.
- Find a container with a lid that is large enough to fit your jar/bag/bottle of cannabis with a little room for your damp, folded paper towel.
- Wet a fresh paper towel with just enough distilled water to get it about 70% damp. Don’t get your paper towel too wet, because excess moisture can lead to mold.
- Place your open container of cannabis and your paper towel in your designated container and seal for 2-12 hours.
This process should slightly improve the relative humidity of your cannabis. This isn’t a silver bullet for dry buds, but it should help.
Note: This method is not a long-term solution—the more times the bud is re-hydrated, the more susceptible it is to mold. Be sure to replace your paper towel and clean your container between hydration attempts.
Fruit Peel Method
A fruit peel can be a nice way to up the moisture of your cannabis while gently infusing your dried-out herb with a light fruity undertone. While the flesh of an orange holds most of its juices, the peel contains much of its essential oils and essences. Peels work well for re-hydrating cannabis because they are natural and moist without being damp.
As with many of the options on this list, this is a temporary fix. Do not—I repeat—DO NOT use fruit peels as a long-term humidification solution. Doing so is a surefire recipe for mold. Personally, I would recommend using a peel for 1-3 days before discarding it (or composting it, if you have the option).
Be sure to leave a little space between the fruit peel and your bud. This can be accomplished simply by having your cannabis in a perforated sandwich bag inside another sandwich bag.
Boveda Humidity Control Packets
(Courtesy of Boveda)
Boveda is a self-regulating disposable humidity pack that helps maintain relative humidity. Ideally, cannabis is stored at 55-62% RH (relative humidity). Luckily, Boveda designed a humidity pack specifically for cannabis consumers.
The Boveda 62% RH is a small, rectangular packet that is squishy to the touch. Boveda’s unique exterior packaging allows moisture to pass through freely, humidifying the contents of a bag or jar over time.
Boveda’s lifespan depends on the current humidity of the starting materials and the quantity of cannabis that needs re-hydration. When the Boveda is spent, the packet will lose its pillowy texture and become firm. You can replace Boveda packs as needed.
(Courtesy of Cannador)
It may be the fanciest option of the bunch, but a cannabis humidor offers the best long-term solution to humidity control. A humidor is usually a cedar-lined box that contains a hygrometer to monitor relative humidity.
Some cannabis humidors, like the Cannador, feature a high-tech bluetooth humidity monitoring system. While a calibrated analog hygrometer works just fine for most people, having a discreet monitor for your cannabis’ relative humidity right on your phone is a truly modern perk.
Humidors maintain their humidity in a couple of different ways. Distilled water and sponge humidifiers work fine, but this requires a bit of monitoring to keep humidity at the perfect level. Other propylene glycol mixtures will regulate at a certain humidity—just make sure you pick a solution that has a RH below 65%. PG solution for cigar humidors usually start at 70% relative humidity, so be aware and pick up the correct bottle.
These are just a few methods that I’ve found success with, but chime in and share your favorite way to keep your buds fresh.
Keeping your cannabis fresh can lengthen its lifespan, but it is also possible to fix dried cannabis with re-hydration techniques. Learn all about how to fix your dry cannabis buds.