Updated: Jan 10
MedLock | August 12, 2021
Revised December 2022
Like other plants and herbs, cannabis spoils over time. This includes the growth of mold which can be harmful when ingested. However, there are ways to prolong the life of your cannabis flower. But first, you need to understand the causes of cannabis degradation.
What Causes Cannabis to Go Bad?
When cannabis begins to spoil, it does not do so in the same way food items do. However, cannabis can grow mold over time and it can even develop an unsavory odour and flavour. There are several key factors that can catalyze the degradation of cannabis.
Exposure to Oxygen: Balancing the amount of air is essential when curing cannabis flower. Too much oxygen can cause the oils and terpenes in the flower to evaporate, which can trigger rapid deterioration of cannabinoids. Oxidation causes THC to convert into a less potent cannabinoid called cannabinol (CBN). As such, air flow most be carefully controlled during curation and storage.
Humidity: Cannabis can be greatly impacted by humidity levels. Elevated humidity introduces moisture into the environment. Increased moisture can cause mold growth and impact the flower's flavour and aroma. In contrast, low humidity causes cannabis flower to over-dry, creating a rather crispy and frail bud. Recommended optimal humidity levels when curing cannabis are approximately 60% to 65% humidity. Some say as low as 55% is acceptable.
Light: UV rays can cause various organic matter to breakdown. For cannabis, exposure to UV rays causes THC to degrade. This is why it is recommended to store your cannabis in a dark place to limit exposure to the sunlight and its harmful UV rays.
Temperature: Another main contributor to cannabis degradation is temperature. Not only can heat contribute to bacterial growth and mold, but heat can also act to physically alter the chemical structure of cannabinoids in a process called decarboxylation.
While decarboxylation (the removal of the carboxyl group on THC-A resulting in THC) is needed to produce the psychoactive effects of THC, too much heat can cause this molecule to degrade into CBN. On the other end of the spectrum, cold temperatures increase humidity. This draws out moisture to the plant's surface causing trichomes to break down. The recommended temperature range for curing cannabis is 21°C or 70°F.
How Do I Prevent Cannabis Degradation?
Given that cannabis is organic matter and therefore perishable, it will eventually degrade. However, you can prolong the shelf life of your bud by using storage methods that control for oxygen, humidity, light, and temperature. These storage methods will help maintain your cannabis flower's aroma, potency, and flavour.
Recommendations for Storing Cannabis
Here are some effective recommendations for storing cannabis to extend shelf life and decelerate the process of cannabis degradation.
First and foremost, cannabis must be stored in an airtight vessel. Airtight containers, bottles, and jars are super easy to find as they are often used to store perishable items in your kitchen pantry. However, ensure you are using glass or ceramic containers and jars instead of plastics and metals. Not only is glass packaging airtight, but it also helps reduce the smell of the cannabis.
Glass Over Plastic
Unlike glass, other materials can affect the taste and aroma of your cannabis. Glass does not release any chemicals that could affect the flower's terpenes. Containers made of metal can contribute to a change in the taste and smell of your flower. Plastic containers are not recommended because they are more prone to creating a static charge that can cause trichome loss.
Glass mason jars are an affordable and popular option for storing cannabis. They also come in many different sizes to accommodate various amounts of flower depending on your yield. Just remember to keep glass jars in a dark place away from direct sunlight.
Store in a Cool, Dark Place
Ask discussed, exposure to light and various temperatures can negatively impact your cannabis. Opt to store your cannabis in a cool, dark place without direct sunlight. Remember, both heat and light can cause accelerated cannabis deterioration. Basements and cellars are usually a safe bet when it comes to storing cannabis.
This brings us back to glass. For added storage protection, glass can come in dark colours and shades. A blacked-out glass jar can keep cannabis safe from the harmful effects of ultraviolet light and prevent oxidation. It is also a better material for maintaining humidity and temperature within the storage vessel.
As a reminder, the optimal temperature for storing cannabis is 21°C or 70°F. The optimal humidity level is usually around 60%. Any humidity level over 65% can negatively impact your cannabis bud.
We discussed how oxygen can impact cannabis flower. When choosing a storage vessel, make sure its size is relative to the amount of bud you have. If you have a small amount, it is best to avoid using a massive jar with a large amount of open air space. Too much oxygen can cause rapid THC degradation.
Limiting oxygen and airflow can preserve cannabis flower longer. However, this does not mean you should be cramming a large amount of flower into a jar either. Packing flower too tightly will restrict airflow entirely, which can lead to elevated humidity levels.
Another great product to include in your cannabis storage vessel is a humidity pack. These small sachet can help regulate humidity levels within the jar/bottle/container, etc. Specifically, humidity packs balance the moisture levels within the storage vessel to ensure there is not too much or too little moisture in the air as well as the plant. A popular brand that sells humidity packs and similar products is Boveda.
Comments on Vacuum Sealed Storage
Many people have asked if cannabis can be stored in vacuum sealed bags. While this may prolong the life of your cannabis bud, this is only if the flower has been properly cured and is therefore free of moisture. Fresh buds, those that have not cured long enough, and improperly cured cannabis flower cannot be stored in an vacuum seal bag due to the moisture level in the flower. The moisture contained in the bag has nowhere to evaporate to and will therefore cause bacterial growth and mold.
Storing Cannabis Around Children
If you have children our teenagers in your household, it is imperative to ensure all cannabis is stored in a locked cabinet, box, cellar, etc. Since glass mason jars are not usually child resistant, storing your cannabis under lock and key is the easiest and most effective way to keep children safe. If you have teens, just be sure to keep the key in a secure place.
One final key piece of information to be aware of is the shelf life of cannabis. Even when optimally cured and stored, cannabis flower typically stays fresh for 6 months to one year. You can usually tell when cannabis flower has gone bad because it will have a distinct aroma (almost like dried hay), the colour may change, and it may even have mold. While trichomes appear to look like little hairs or crystals sitting on the leaf, mold looks like a gray or white powder.
Avoid These Common Cannabis Storage Mistakes
Here are a few common mistakes many people make when curing and storing cannabis flower:
Failing to burb the jars. Opening the lids of your jars for about 15-30 minutes each day for at least two weeks during the curing process is essential for optimally drying cannabis flower.
Freezing cannabis flower. Why would anyone try this, we don't know.
Overpacking cannabis flower into storage containers.
Failing to use humidity packs. These are small and very easy to add to a jar when curing and storing cannabis.
Adding foreign materials. This, of course, does not include humidity packs.
Using storage containers made from toxic materials. Again, choose glass.
Storing different strains in the same jar (for obvious reasons). Different strains have different bud qualities and psychoactive qualities. Ensure strains are stored separately.
Forgetting to label jars and containers. It is always helpful to label your storage vessel with the date it was harvested and cured. If you grow multiple strains, also include the name of the cannabis strain on the label to differentiate between buds.
Like any other plant or herb, cannabis can rot. The key factors that cause cannabis to degrade are exposure to oxygen, humidity levels, temperature, and exposure to light. However, all of this can be prevented by using the curing and storage techniques discussed here. Using airtight glass storage with a humidity pack thrown in is a sure way to slow down the process of cannabis degradation.