Good quality cannabis should be spongy and stick to your fingers. In perfect conditions, it should stick to itself; I've seen a whole pound of properly dried and cured sticky buds stick together in one large chunk.
For many commercial growers, the preferred method of drying cannabis to achieve that desired result is to place the harvested plants, branches, or buds in an environment with a relative humidity (RH) of 60% and a temperature of 60°F. Their goal is to achieve a final water activity (WA) level of 0.6. At this level, bound water stays in the buds, maintaining freshness, and unbound water is dissipated to minimize microbial activity.
They follow the rule that the drying is done when the bud’s inner stem audibly cracks when bent.
After drying, the buds are traditionally placed in bins, totes, or another sealed container to “cure” them. Typically, this involves periodically opening the containers to vent any unwanted moisture and/or gases such as ethylene and CO2, and replacing the unwanted saturated air with new air. This process is commonly referred to as “burping” the containers and is repeated until a desired moisture content is homogeneously achieved across buds of all sizes.
Legacy Systems
These environmental conditions are traditionally achieved by employing HVAC systems with integrated dehumidifiers (or with standalone dehumidifiers). These systems can have large operating variances for when they kick on (i.e., an HVAC may turn on when temperatures stray more than 2°F from the setpoint, while another may only turn on after a shift of 4°F).
That spread can result in short-cycling (where systems turn on and off rapidly), which in turn encourages the trichome heads on the buds to expand and contract. Each time this action takes place, both moisture and terpenes are evaporated and lost to the environment forever, typically resulting in overdried cannabis that has an inner stem that audibly cracks when bent but whose resin glands are dry like a grain of sand.
Overdrying cannabis results in buds that are not sticky, are less aromatic and flavorful, have no desirable bound moisture content, and crumble when squeezed.
Improperly leveraging this traditional equipment is responsible for the majority of overdried cannabis available today and for the loss of a staggering amount of terpenes.
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To be clear, these methods and equipment remain sufficient for small-scale production, and it is possible to get fantastic craft quality utilizing them. Even some larger, well-established operations may find success with them.
The problem typically arises from medium and large-scale producers whose top priority when drying is microbial growth prevention. To prevent such microbial growth, many companies purposefully overdry their cannabis, then reapply terpenes to enhance flavor and utilize moisture packs to rehydrate the buds or pre-rolls.
But once overdried, the buds can't be properly cured, and a majority of the monoterpenes will be sacrificed and evaporated. Remember: If you smell terpenes, you are losing flavor.
Newer Innovations in Cannabis Drying and Curing
In response to this issue, some forward-thinking companies have been performing expensive research and trials to identify precise and exact set points and ranges, as well as advanced equipment to enable a large-scale producer to precisely replicate the perfect environmental conditions that are conducive to drying and curing.
For example, instead of utilizing dehumidifiers, some growers are utilizing alternative systems such as Cannabis Mechanical’s ReHeat to eliminate unwanted moisture while minimizing monoterpene content loss.
Another company, Cannatrol, has designed drying environmental equipment that was adapted from the cheese industry. This system does not utilize traditional dehumidifiers or HVAC and aims to precisely control vapor pressure, enabling growers to establish desirable drying conditions that are predictable and replicable for each and every harvest.
There is also specialized equipment available that facilitates creating a replicable environment for proper curing. Keirton’s Cure Puck automatically burps a container if moisture or gas levels exceed set points, optimizing the water activity levels and reducing microbial contamination risk from humidity buildup. This equipment also gives a grower complete control over multiple curing factors across a plethora of containers, helping preserve a higher percentage of monoterpenes.
Advice in Practice
I recently had the pleasure of consulting for a company on its proposed drying and curing procedures, protocols, and overall layout.
They proposed multiple traditional dry rooms utilizing HVAC and dehumidifiers and a hang-dry system. The overall layout and design were great. First, I suggested they consider an alternative method of drying that focused on moisture and terpene preservation.
They also had no provisions yet for curing or storage rooms, so I suggested they turn one of their drying rooms into an area to properly cure the buds after drying, and explained that the curing room, trimming room, and packaging environments will also require precise climate control to minimize moisture and terpene loss to evaporation, especially while trimming and packaging.
I also explained that, at the scale they were operating, the revenue increase from having a higher quality product would eventually pay for the equipment upgrades (like those mentioned above), and they would be able to offer customers a superior, properly dried and cured, aromatic, sticky product.
