By Grubbycup

Taking care of your cannabis can ensure that the last of the smoke is at least almost as good as the first. Outdoor home gardeners in particular tend to have a lot of cannabis at harvest, which may have to last until the next harvest. When stored in an airtight container, properly dried and cured cannabis should be stable for months without needing to be opened for humidity purposes. 

Keep It Dry

The ideal humidity inside the container should be around 60% at room temperature (70 degrees Fahrenheit or so). Warm air can hold more moisture than cool air can. Moist cannabis can quickly become a host for mold under warm and wet conditions. Any ammonia aroma is an indication that the cannabis is starting to decompose and mold.

Humidor products can help maintain proper humidity. For example, commercial natural salt packs can absorb or release moisture as needed. Be careful about actual humidors made for tobacco though, as some are not airtight, or are made with cedar or other woods that can impart an off flavor to any exposed cannabis.

For cannabis that is becoming too dry, a smallish piece of terracotta flower pot can be dipped in water and shaken off, then placed in the container to raise the humidity. Do not use pieces of fruit or other foods to rehydrate cannabis as they can mold easily, and moldy cannabis is worse than overly dry cannabis.

Keep It Cool

Cannabis can be stored at room temperature or cooler. A constant temperature is better for storage than temperatures that fluctuate. If perfectly dried and cured cannabis is placed in a sealed container in a warm location, the warmer air will be able to hold more moisture, and will draw additional moisture from the cannabis. This can dry out the cannabis material beyond what is desirable. If the container is then allowed to cool, that additional moisture can precipitate back onto the surface, potentially leading to a mold issue. Heat also increases the speed at which terpenes evaporate into the air, reducing both flavor and aroma. 

If any moisture collects on the sides of the container (possibly due to not being properly dried) the jar should be opened for a while to reduce the humidity in the container, or the cannabis should be removed and allowed to dry out before returning to storage, depending on the severity of the moisture. During curing this is commonly referred to as “burping” often means the cannabis was too moist before being sealed. 

Storing in the refrigerator, especially one that is in use for food, is not recommended. Every time the door opens the air conditions change. Between the fluctuations in temperature and humidity associated with normal refrigerator use, cannabis stored in a cool but non-refrigerated area tends to fare better than in a normal kitchen fridge. 

Freezing cannabis can extend the storage life almost indefinitely, but it makes the trichomes brittle and easily broken off (which is done on purpose when making some forms of hash), If you do freeze, keep it in a sealed container to avoid becoming “freeze dried,” as any water in the plant cells can rupture the cells, reducing structural integrity. Any air in the container can lead to “freezer burn.” It is usually not recommended to freeze cannabis unless you are fresh freezing for processing “live” material to make concentrates, or for long term storage of concentrates. 

Keep It Dark

Light, particularly UV light, can bleach and discolor the plant material, and accelerate degradation of the active ingredients. Cannabis kept in a dark closet will generally last longer and retain better quality than cannabis exposed to light.

Keep It Air-tight

An airtight container limits the exchange of air from inside and outside the container. This is important for controlling moisture and essential oil evaporation. It also helps slow oxidation by limiting the amount of available oxygen. Keeping the airflow restricted also helps maintain consistent humidity. 

Mitigate oxygen exposure by either using oxygen absorbing packets, or by filling the interior of the container with nitrogen gas. Either way the benefits only last as long as the container stays sealed, and are more suitable for long term undisturbed storage than the average home consumer needs.

Left: Grubbycup used acid etching to decorate this canning jar. Middle: Using a technique known as felting, Grubbycup made a cover for this canning jar using wool and a hooked needle. Right: Canning jars labeled and ready for a dark drawer.

Keep It Glassy

Glass containers are popular because they don’t react with the cannabis. Expandable plastic bags can be difficult to remove the last of the shake from, and trichomes can become attached to the sides of plastic bags through static electricity and mechanical action. Glass containers are frequently not lightproof themselves, so keep them someplace dark.

Commercial cannabis products are more likely to be sold in bags or plastic containers of some sort, not necessarily because they are superior for storage but because they are cheaper and easier from a packaging, regulatory, and shipping perspective. 

Choose Containers Wisely

Since air, particularly oxygen, inside the container can have a detrimental effect on cannabis, use the right size container for the amount of cannabis you have, with minimal headspace, or have a partial vacuum inside the container. This isn’t always practical however, and the impact it makes isn’t huge.

Sandwich bags and similar bags can help keep the cannabis dry. From a storage perspective they aren’t the most ideal, but they are common, cheap, and easily accessible. Improved sandwich-style bags are common in commercial packaging. These bags tend to be thicker, and are often opaque. They also frequently have a side benefit of having a tear off top above the press seal, to make tampering or opening obvious. This may not be a necessary consideration for home gardeners intending to use their home grown cannabis themselves, but is a handy feature for commercial concerns.

Vacuum-sealed bags eliminate much of the air, but care should be taken not to crush the cannabis or the visual appeal will be reduced, which may give the appearance of mistreatment. Vacuum-sealed, rigid containers offer similar benefits without the physical damage. 

There are jars made from UV-proof glass that can be used. The UV protection only applies if the jar is exposed to light, as in a dark environment the UV protection makes little difference. Due to the damage that can be caused by heat, it is not recommended to leave even UV-proof glass jars in direct sunlight.  

There are also a variety of other special purpose stash jars on the market. Some are obviously more temporary holding spaces, but some are marketed for long-term use. Before purchasing these, look closely at the way the lid seals to the jar, as some have odd fittings that can be inconvenient to use on a regular basis, and some have loose fitting lids which can reduce freshness.

A popular (and my personal) choice for home use is canning jars. They are made of glass (except for the lid and collar), are air tight, and can be purchased in a variety of convenient sizes. They are reasonably priced for the quantities most consumers need, and can be decorated or left plain. When cannabis in these jars are stored in a cool, dark, rarely disturbed location, cannabis can be kept usable for longer than most consumers take to use it, meaning at least a year.

The longer cannabis is expected to be stored, the more important it is that it be stored properly. A week’s worth can be kept reasonably fresh even in a plastic bag for the short time needed, but to keep cannabis reasonably well for a year or longer takes some planning as far as a proper location and a suitable container.