The drying process is a necessary post-harvest step that removes excess moisture from cannabis plant material, transitioning it between harvest and the final curing stage. Controlled moisture reduction is necessary for preserving the compounds that define the quality of the final product. The goal is to dry the flower slowly enough to allow a chemical breakdown of undesirable compounds, but quickly enough to prevent mold or mildew. Proper drying maximizes the retention of volatile terpenes and helps maintain cannabinoid potency.
Pre-Drying Preparation: Trimming and Breakdown
Immediately after harvest, the physical manipulation of the plant material influences the rate and quality of the drying process. Growers must decide between wet trimming (done before drying) or dry trimming (performed after drying). Wet trimming removes all excess fan and sugar leaves while the plant is fresh, making the process faster and easier. This method reduces the risk of mold in highly humid environments and saves considerable space, as only the buds remain.
The primary drawback of wet trimming is the potential for quality loss, as the exposed flower dries much faster, which can lead to a harsher smoke due to chlorophyll retention. Removing the protective layer of leaves also increases the exposure of the fragile trichomes to oxygen and physical damage, potentially leading to the premature evaporation of terpenes. Dry trimming involves hanging the entire plant or large branches with all foliage intact, using the leaves as a natural barrier to slow moisture release. This slower, controlled drying rate is preferred for maximizing terpene preservation and promoting a smoother final product.
After trimming, the harvested material must be broken down for hanging, which also impacts the drying time. Hanging the entire plant or large branches is a traditional method that facilitates a slower, more uniform drying process because the plant’s structural mass holds more moisture. This approach minimizes handling and protects the resin-rich trichomes from damage. However, this method requires a large amount of dedicated drying space and takes longer to complete.
Cutting the plant into smaller, individual branches or separating the buds entirely accelerates the drying process due to increased surface area exposure and airflow. While this is an efficient technique for growers with limited space, it necessitates more handling, increasing the risk of mechanical trichome loss. A good compromise is often to remove the largest fan leaves, then hang medium-sized branches, balancing the need for controlled drying with space efficiency.
Establishing the Optimal Drying Environment
Creating a stable and precisely controlled environment is the most important factor for achieving a high-quality dry. The ideal temperature range for the drying space should be maintained between 60 and 70 degrees Fahrenheit (15–21 degrees Celsius). Temperatures exceeding this range, particularly above 75°F (24°C), can cause volatile terpenes to evaporate prematurely, resulting in a noticeable loss of flavor and aroma.
Temperature works in tandem with relative humidity (RH), which should be held between 45% and 65% for a slow, gentle dry. A common target is 50–60% RH, which prevents the material from drying too quickly, a process that locks in harsh flavors. Humidity levels that are too high, generally above 65%, pose a serious risk for the development of mold and mildew, especially on dense flower material.
The drying room must also be kept completely dark to prevent the degradation of active compounds. Ultraviolet (UV) light exposure, even from common light sources, accelerates the breakdown of tetrahydrocannabinol (THC) into less potent compounds like cannabinol (CBN). Darkness ensures that the chemical structure of the cannabinoids is preserved, maximizing the potency of the final product.
Gentle, consistent airflow is necessary to remove the moisture that is constantly evaporating from the plant material. Air circulation should be managed with oscillating fans that move the air indirectly, rather than blowing directly onto the buds, which would cause them to dry too quickly and unevenly. Hanging the material upside down on lines or racks is the standard practice, as this setup utilizes gravity to help draw moisture out of the flower, ensuring a uniform and controlled drying process.
Assessing Readiness and Transitioning to Curing
The drying process is typically complete when the flower has reached a moisture content of approximately 10–12%. This level signifies that enough water has been removed to prevent microbial growth while still retaining sufficient internal moisture for the subsequent curing phase. The most common and reliable method for determining readiness is the “snap test,” which is a physical assessment of the stem’s condition.
A bud is considered sufficiently dry when a small, pencil-sized stem snaps cleanly with an audible break rather than merely bending or folding. If the stem bends, it indicates that too much moisture remains inside the core of the flower material. For growers seeking greater precision, a specialized moisture meter can measure the exact percentage of water remaining.
The overall duration for proper drying generally falls between 7 and 14 days, though this timeline is highly dependent on the stability of the drying environment. Fluctuations in temperature or humidity can drastically shorten or extend this period, emphasizing why strict environmental control is so important. Once the snap test confirms the material is ready, it must be immediately moved to the next phase of post-harvest processing. This next step is curing, where the dried flower is sealed in airtight containers, such as glass jars, to allow for the preservation of flavor. The immediate transfer ensures that the flower does not become overly dry, which would result in a brittle texture and a loss of the remaining volatile compounds.