Drying cannabis is the process of converting freshly harvested plant material into a stable, usable product. This step removes excess water, which prevents the growth of mold and mildew. Hang drying is the traditional and most recognized method, valued for its ability to facilitate slow, controlled water loss. This gradual process is particularly effective at preserving delicate compounds, such as aromatic terpenes and cannabinoids, that define the final quality of the flower.
Preparing the Material for Drying
Before the drying phase begins, a decision must be made regarding when to remove the excess foliage, known as trimming. The choice lies between wet trimming, which occurs immediately after harvest while the leaves are still full of moisture, and dry trimming, which is performed after the branches have fully dried. Wet trimming offers the advantage of faster drying times and reduces the risk of mold in humid environments, as the moist leaves are removed right away. However, this method can cause the buds to dry too quickly, which may result in a harsher final product due to chlorophyll retention.
Dry trimming, conversely, involves leaving the sugar leaves and some fan leaves attached during the entire drying period. These remaining leaves act as a natural humidity buffer, significantly slowing the rate of water evaporation from the flower. The slower drying process is credited with achieving a smoother, more flavorful smoke because it helps retain a higher concentration of volatile terpenes. While it makes the trimming process less sticky, the leaves curl tightly around the buds once dry, making the post-drying removal more difficult and time-consuming.
Creating the Optimal Drying Environment
Achieving a successful hang dry relies on establishing a controlled atmospheric environment. The ideal temperature range for a drying room should be maintained between 60–70°F (15–21°C). Temperatures exceeding this range cause the buds to dry too rapidly, leading to the premature evaporation of aromatic terpenes and a less desirable final flavor.
Equally important is the relative humidity (RH), which should be kept within a target range of 45–55%. If the humidity level rises above 60% RH, the risk of mold and bud rot significantly increases. Conversely, humidity levels below 40% cause the buds to dry too quickly and become brittle, preventing the necessary slow release of moisture from the center of the flower.
The drying space must also be kept completely dark to protect the cannabinoids and terpenes from light degradation. Ultraviolet light can cause tetrahydrocannabinol (THC) to break down, reducing the potency of the final product. Air circulation is maintained using a fan, but it should never blow directly onto the hanging material. Instead, a gentle, passive airflow should be created to circulate the air and prevent isolated pockets of high humidity from forming.
The Step-by-Step Hanging Process
Hang drying begins immediately after the harvest and initial trimming are complete. Most growers choose to cut the plant into manageable branches ranging from 12 to 18 inches in length, rather than attempting to hang the entire plant. This approach allows for better air circulation and makes the material easier to handle within the drying space. The larger branches are then suspended upside down from a line, wire, or dedicated drying rack.
It is important to ensure that all branches and buds are spaced adequately so that none of the material is touching another piece. Contact between buds can trap moisture, creating microclimates where mold can easily take hold. The typical duration for a complete hang dry is between 7 and 14 days, though this timeframe is dependent on the density of the buds and the stability of the environment.
Daily visual monitoring is necessary to check for any signs of mold or uneven drying. If parts of a branch appear to be drying slower than others, minor adjustments to the spacing or airflow may be needed. The integrity of the final flower shape is best preserved by hanging the buds rather than laying them flat on a rack, which can compress them.
Determining When Drying is Complete
The primary indicator that the drying process is finished is the “snap test.” This test involves gently bending one of the smaller, thinner branches or stems that lead into a bud. If the branch bends without breaking, it still contains too much internal moisture and requires more time in the drying environment.
A ready-to-cure branch should snap cleanly and audibly when bent, indicating that the bulk of the water has been removed. Although the buds may still feel slightly spongy inside, the exterior should feel dry. The target internal moisture content at this stage should be around 10–12%.
If the material is removed too early, the excess moisture can lead to mold during the subsequent curing stage. Conversely, if the material is allowed to become overly dry, it will feel brittle and lose valuable terpenes, resulting in a harsher experience. Once the snap test is conclusive, the dried flower is ready to be trimmed into individual buds and transferred to airtight containers to begin the curing process.