Drying and curing are the most critical post-harvest steps in hemp production, directly impacting the final quality, cannabinoid potency, and consumer appeal of the biomass or flower. Proper execution minimizes mold and preserves the volatile terpenes and cannabinoids.
I. The Drying Phase: Initial Moisture RemovalThe goal of the drying phase is to rapidly remove surface moisture while slowing down the process to allow internal moisture to diffuse out evenly.
A. Environment and SetupA controlled environment is essential. Uncontrolled drying can lead to mold growth or, if too fast, result in brittle, chlorophyll-retaining biomass.
- Location: A dedicated, clean, and dry space away from direct sunlight is required. Ventilation: Use fans to circulate air, but do not blow air directly onto the plants, which can cause uneven drying.
- Hanging: Hang whole plants or large branches on wires or racks to maximize airflow. Never pile wet plant material.
B. Temperature and Humidity Control
Maintaining a consistent environment is key to a slow, controlled dry.
Parameter | Recommended Range | Purpose |
|---|---|---|
Temperature | 60–70°F (15–21°C) | Prevents terpene degradation and rapid drying |
Relative Humidity (RH) | 55–65% | Slows moisture removal, prevents mold |
Airflow | Gentle, consistent circulation | Removes moist air without directly hitting plant |
The drying process is complete when the hemp flower's external moisture content is between 10–15%.
- The Snap Test: A common indicator is the "snap test." Small branches should snap when bent, but the main stalk should still be slightly flexible.
- Moisture Meter: For large-scale operations, using a specialized moisture meter is the most accurate method to verify the internal moisture content of the biomass.
- Checking for Mold: Inspect the plants thoroughly before moving to the curing stage.
III. The Curing Phase: Quality and Preservation
Curing is a slow, controlled process of aging the dried hemp in sealed containers. This process allows residual moisture to even out and chlorophyll to break down, resulting in a smoother smoke and better flavor.
A. Curing Containers and Process- Containers: Use large, airtight containers, such as food-grade totes or curing barrels.
- The "Burping" Process: Place the dried flower into the containers and seal them. For the first week, open or "burp" the containers for a few minutes, two to three times a day. This releases built-up moisture and introduces fresh air, preventing anaerobic bacteria growth.
- Timeline: The initial aggressive burping phase usually lasts about one week, followed by burping once a day for two to four weeks.
B. Long-Term Curing Storage
After the initial curing period, the hemp can be stored for long-term preservation.
- Storage RH: For long-term storage, the ideal relative humidity (RH) inside the container is 58–62%.
- Packaging: Move the cured flower to final packaging—such as vacuum-sealed bags or opaque jars—to minimize light and air exposure.
IV. Post-Cure Quality Assurance
To maintain quality and compliance, samples should be sent for testing after curing.
- Testing: Send samples to an accredited lab to confirm cannabinoid potency (THC/CBD) and to screen for heavy metals, pesticides, and microbial contamination (e.g., mold).
- Documentation: Record all temperature, humidity, and burping data for compliance records.