Cannabis is perishable, which means that at some point in time your cherished fresh flowers are going to expire and not be usable. What was formerly a fresh-smelling, vibrant green bag of cannabis buds eventually will lose its vibrant hue and pungent aromas. At some point, the fluffy buds will also crisp up and then dry out, which will leave you with a dismal product. This is due to the degradation process, and cannabis has to play by all of the same rules that other harvested crops do.
Fortunately, the factors influencing the degradation process of cured cannabis flowers are relatively easy to control and understand.
What’s The Freshness Time After Harvest?
The cannabis plant starts to degrade as soon as it has been harvested. The plant is not only not alive any longer and receiving nutrients from its root ball that it was formerly attached to, but there has also been a disruption to its cannabinoid biosynthetic pathways. This process involves the terpenes and cannabinoids synthesizing into other compounds, which alters their psychoactive properties in the process. For example, the temperature can cause the substance THCA to decarboxylate to become THC (a highly psychoactive substance). However, light and heat can also cause THC to degrade into CBN.
After a cannabis plant is harvested, and then dried and cured, there is only a finite window of time where its freshness zone is optimal, and only can be extended through controlling various elements carefully, which include not only relative humidity and temperature but also ambient oxygen levels and UV exposure.
How does temperature effect degradation?
There are several ways that the degradation of cannabis can be affected by temperature. Cannabis should ideally be stored at temperatures that do not exceed 70F degrees if it is any higher than that it starts introducing an environment that is conducive to mold and bacterial growth inside of the flowers.
Also, volatile monoterpenes start polymerizing at very low temperatures, which mean the aromatic profile and flavor of the cannabis flowers can also change. When cannabinoids are exposed to high temperatures for prolonged periods, they start to degrade and decarboxylate. In this process, THCA will lose its carboxyl ring first, which converts it into THC. Eventually, it can deteriorate into CBN through being exposed to elevated temperatures for long periods.
Conversely, if cannabis is kept at too cold of a temperature, for example in a freezer, that can risk increasing relative humidity levels, and that may force moisture into the plant’s surface and in the process break trichomes down.
By itself, high relative humidity may affect the degradation of cannabis by introducing high moisture levels into the flowers once again. When cannabis is harvested, fluid transfer is slowed down rapidly during the curing and drying phases. Cannabis should be optimally stored in relative humidity of the 59-63% range to avoid adverse degradation.
When high moisture levels are reintroduced, cannabis flowers are at increased risk of mold growth and ammoniated flavors may be caused as well due to a restriction in air circulation. Low humidity, on the other hand, may impact cannabis degradation negatively by drying out foliage and leaves, which causes them to become fragile and brittle.
Oxygen And UV Light
Humidity and temperature both profoundly influence the degradation of cannabis, and high exposure to oxygen and UV light can cause perhaps the highest degradation rates within the shortest amount of time. UV rays may break organic matter down rapidly which results in loss and degradation in cannabinoids. The only way to slow down this process is to limit the amount of light that cured flowers are exposed to.
Increased oxygen exposure cause cannabinoid degradation to occur rapidly as well. When THC is left in environments that are highly oxidized, it converts to CBN more quickly, and that is why it is significant t control both RH and oxygen levels when cannabis buds are being cured.
In summary, the four major factors influencing cannabis degradation are light, airflow, humidity, and temperature. All four of these variables are a spectrum which harvested cannabis flowers all teeter on. When these variables are controlled and maintained at the right levels, it can significantly prolong the cannabis flowers shelf life through limiting exposure to those processes which influence degradation of the floral clusters as well as the terpenoids and cannabinoids that are contained inside of the flowers.
Cannabinoid degradation is inevitable, and eventually, your cannabis does expire. However, the best way of combating the natural processes that will leave your stash undesirable is to maintain a highly controlled environment, which will leave your flowers fresher for longer than you might have been able to anticipate previously.