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Traditionally, the focus in cannabis has been on genetics and cultivation methods, such as whether the strain is sativa- or indica-dominant, or if it’s grown indoors or outdoors. While these are essential factors, post-harvest storage often gets overlooked. Yet, maintaining the right relative humidity (RH) for harvested cannabis flowers is crucial to preserving their quality, cannabinoid profile, and distinct characteristics. For producers, controlling moisture levels not only improves the product but also protects profits by preventing weight loss due to evaporation.

Cannabis is a delicate plant, and fluctuations in moisture levels can significantly impact its quality and efficacy. Too much moisture creates an environment where mold and fungi can thrive. On the other hand, too little moisture causes the plant to dry out, reducing weight and degrading essential compounds like cannabinoids and terpenes. The same harvest can yield flower of vastly different quality, depending on whether or not it’s kept at an appropriate post-harvest moisture level.

According to standards set by ASTM International, the optimal RH range for storing cured cannabis is between 55% and 65%. [1] Research by Boveda, a leader in humidity control for cannabis, fine-tunes this range further to 58%-62%, ensuring optimal preservation and quality.

The key variable for cannabis is RH, a measurement of water vapor compared to the saturation point of its current environment and temperature. For simplicity’s sake, this discussion will refer to optimal RH ranges for cannabis storage. Scientifically speaking, the environmental RH affects the flower’s free water level, known as water activity (Aw). Because water activity is expressed as a decimal, the values for RH percentage and water activity can be viewed similarly. For example: 0.58 Aw = 58%RH.

When cannabis stays in the optimal RH range, it realizes its full potential for quality and profitability. There are some stark consequences—from the medical to the economical—when there are deviations above or, more commonly, below this range.

In the early, unregulated days of cannabis, inconsistent storage practices were tolerated. But as industry standards rise and profit margins tighten, companies that neglect humidity control will face costly consequences, with lost revenue as the market's harsh response.

There are two central issues with overly dry cannabis: significant loss of weight and compromised cannabinoid profiles.

The weight of the flower directly correlates with profitability. The heavier the yield, the higher the market value. Simple enough, right? Not quite.

Cannabis flower needs to be dried and cured after cultivation, but some cultivators, processors and packagers only worry about keeping the flower below a particular humidity “ceiling” while neglecting to ensure the flower stays above a certain “floor.” It is not uncommon for cured cannabis to be stored for up to two months prior to sale or consumption, and by the time it reaches the end consumer, most cannabis sold in regulated environments in the U.S. and Canada is far too dry.

The results of a 2018 product analysis conducted by Boveda with third-party testing are eye-opening: Of 72 cannabis samples purchased across five state markets, 67% of samples were below the optimum RH range (55-65%). And of those flower samples that tested within the target RH range, multiple samples were teetering on the cusp of the lowest optimal RH threshold, indicating significant room for improvement across the board. 

Overdrying directly affects the bottom line—much more than many cultivators realize. For example: 

With 1,000 pounds of cannabis, if there’s a 5% reduction of RH below the optimal threshold, that equates to a loss of six pounds (2,721.6 grams); at $5 per gram wholesale, that works out to $13,607 in lost revenue. Regardless of current wholesale prices, this provides a sense of the scale of dollars lost, but not the limits. Boveda’s analysis found that a majority of the cannabis sold today is more than 5% below the optimal range—which comes with a corresponding loss in value. In fact, third-party testing reveals that a bulk of cannabis currently on the market is around 10% below the lowest acceptable moisture level. 

  

Even within that optimal RH range where cannabis flower realizes its full potential, there are still tens of thousands of dollars to be gained from precisely maintained RH. Additionally, cannabis in the optimal humidity range maximizes all the qualities that attract and retain customers.

Cannabis is taxed by weight, and the levels of cannabinoids like THC and CBD are measured as a percentage of that weight. [2] To reduce taxes and report higher potency, some producers dry their cannabis excessively and then rehydrate it just before sale. While this may boost short-term profits, it's a losing strategy in the long run.
This process permanently damages the quality of the flower, leads to risky rehydration methods, and increases the likelihood of stricter regulations.
The downsides far outweigh the tax savings. Customers quickly lose trust when they discover the inferior quality of the product.
Additionally, these manipulative practices put the entire cannabis industry at risk by inviting more regulatory scrutiny and increasing the chances of tougher standards, adding more bureaucratic regulations and oversight.

Consumers, especially medical patients, are becoming more familiar with cannabis components like terpenes and cannabinoids, which are key to the plant's medical benefits.
Cannabinoids are chemical compounds that interact with the human endocannabinoid system, which includes receptors throughout the body. THC, CBD, and other cannabinoids are often used as a quick way to measure cannabis potency and hint at the effects and health benefits a user might experience.
There are over 100 known cannabinoids in cannabis. Rare cannabinoids like CBG, CBC, CBN, and THCV are being studied more as scientists explore how these compounds work both individually and together.

While cannabinoids are like the "horsepower" of a strain, terpenes provide the "feel of the ride." Terpenes give cannabis its distinctive aroma and taste and are thought to influence the plant’s therapeutic and euphoric effects. Researchers believe terpenes work with cannabinoids to create an "entourage effect," which may determine whether a strain helps with conditions like anxiety, pain, or neurological disorders.
These important compounds are found in the plant’s trichomes—the tiny, resinous hairs on the flower. Since terpenes and cannabinoids make up most of the value of cannabis flower, they’re crucial to the plant’s market price but also highly fragile and exposed.

As any veteran cultivator knows, overly dry cannabis spells big trouble for trichomes.

When harvested cannabis gets overdried, trichomes become brittle and fragile, breaking off and settling at the bottom of the package; they will not be recovered even if the flower is rehydrated. When trichomes are damaged, terpenes can volatilize and escape into the air. If cannabis is dried too quickly or for too long, these valuable terpenes evaporate, leading to a noticeable drop in the quality and flavor of the flower. This issue of terpene loss through evaporation was confirmed in third-party lab tests commissioned by Boveda.

Labels on cannabis packaging detail terpene and cannabinoid levels, offering consumers an idea of the quality and effects they can expect. However, it’s uncertain whether these levels are still accurate when the product is finally consumed.

Cannabis producers need to ensure consistency, not just for customer satisfaction but also for regulatory compliance. As legal cannabis markets expand both in the U.S. and globally, consumers are becoming more knowledgeable about the chemical profiles of strains, seeking out specific terpene and cannabinoid levels.

With social media and instant digital feedback, the connection between cultivators and consumers is more transparent than ever. As the industry rapidly grows, so too does the demand for quality, and producers must meet these expectations to remain competitive. Where once any flower would suffice, today's market expects more refined and reliable products.

When storing cannabis flower, some consumers—and even a few cultivators—try to prevent overdrying by using makeshift methods like fruit rinds, wet paper towels, or tortillas. These crude rehydration techniques are not only ineffective but also pose serious health risks. While harvested cannabis is unlikely to develop Botrytis cinerea ("bud rot"), it can become a breeding ground for Aspergillus, a dangerous mold that thrives in moisture-rich environments.

For cultivators, mold growth results in immediate financial losses and can threaten the long-term success of their brand. Mold-infested cannabis is worthless and must be destroyed, particularly since pathogens like Aspergillus pose serious health risks. In vulnerable consumers, such as those with compromised immune systems, exposure can lead to invasive pulmonary aspergillosis—a life-threatening condition that can spread from the lungs to other organs if untreated.

Given these risks, imprecise rehydration methods are simply unacceptable for any cultivator, regardless of their operation's size.

While the challenges of cannabis storage may seem complex, the solution is straightforward. Two-way humidity control technology can automatically add or remove moisture as needed to maintain a stable RH in the optimal range. These systems, especially those that use natural saltwater formulations, are proven to maintain moisture levels effectively without allowing microbial growth, making them ideal for cannabis storage.

For cultivators, processors, and retailers, proper humidity control can prevent weight loss, protect trichomes, and guard against mold—ensuring the product maintains its quality, safety, and value. Both glycerin and salt-based humidity control products release water vapor when the environment becomes too dry. However, only two-way humidity control, utilizing a natural saltwater solution inside a vapor-phase osmosis membrane, can both add and remove water vapor to maintain a constant RH level. This ensures stable moisture levels in the cannabis flower.

While glycerin may encourage microbial growth, salts prevent this issue and keep moisture levels within a precise range. The benefits of using this system for cannabis storage are substantial. Not only does it preserve the integrity of the flower, but it also enhances terpene retention by coating the trichomes with a thin, protective monolayer of purified water, preventing terpene evaporation and maintaining the product’s potency and aroma.

A third-party lab study analyzed flower cured with 2-way humidity control solutions designed to keep RH at 62%. This study showed that the cannabis retained 18% more terpenoids and 23% more cannabinoids than a control. As a naturally safe material, salt avoids any safety complications if the packet should become compromised (while glycerin can have a laxative effect).

When factoring in the added profitability from increased weight, along with the value-add of enhanced quality from terpene and cannabinoid retention, the advantages of 2-way humidity control are clear.

For cultivators with tight margins, which includes most growers in this highly regulated industry, that can be the difference between operating in the red or in the black.

Properly controlled humidity makes a big difference in the quality, weight, safety and profitability of cannabis cultivation and processing. Fortunately, tackling evaporative loss is easy to address with 2-way humidity control solutions designed to maintain stable optimal RH within packages or containers. Salt-based humidity control solutions with 2-way vapor-phase osmosis technology are proven to achieve substantially more desirable results than other moisture-control methods, and this could translate into substantial profit retention. 

The benefits of properly storing cannabis with humidity control in mind are far-reaching for cultivators, processors and packagers. In this rapidly evolving industry, cannabis brands are building their reputations in real time, and there’s no room to fall behind.

A proven humidity control system is a needed investment for cannabis businesses of any size. 

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