Humidity Control During Drying and Storage

Why humidity during drying and storage is so important

After harvest begins a phase that determines the final quality of your crop just as fundamentally as the entire previous growing cycle. Many growers provide maximum care to their plants, but then neglect drying and storage. The result is often either mold or over-dried material without aroma and with degraded trichomes. Both scenarios are unnecessary losses that can be easily prevented.

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The key parameter of the entire process is relative humidity, abbreviated as RH (relative humidity). It determines how quickly the material dries, whether mold can proliferate, and how long it retains its properties during storage.

Drying phase: slow and controlled is always better

Drying is not just about removing water from the material. It's a controlled biochemical process in which enzymatic reactions occur that affect the final aroma, taste, and texture. Too-rapid drying interrupts these processes, while too-slow drying opens the door to mold.

Ideal conditions for drying

Experienced growers agree on these parameters:

• Relative humidity: 45-55% RH
• Temperature: 18-22°C
• Air circulation: gentle, without direct airflow on the material
• Light: darkness or very dim light (UV radiation degrades trichomes)
• Drying time: ideally 10-14 days, depending on density and branch size

If you dry in an environment with higher humidity (above 60% RH), you risk developing Botrytis mold or other unwanted fungi. Conversely, below 40% RH the material dries too quickly, chlorophyll doesn't degrade properly, and the result is typically harsh and aromatically flat.

How drying works in practice

After harvest, branches can be hung upside down on rope or wire, or laid out on a drying net. A drying net is a practical choice especially when you have limited space or want to dry already-trimmed material. It allows good air circulation from all sides and reduces the risk of damp spots where mold could settle.

Regardless of method, remember: don't pack the material too densely, ventilate the room regularly, and monitor humidity with a hygrometer. A cheap digital hygrometer is one of the most important investments you can make as a grower.

Trimming and its effect on drying

The question of whether to trim before or after drying directly affects the speed and course of the entire process. The leaves surrounding the buds act as natural protection and slow water evaporation. If you trim before drying (wet trim), the material dries faster. This can be an advantage in humid environments, but in dry climates it leads to over-drying.

Conversely, trimming after drying (dry trim) preserves the natural drying pace and generally produces better results in terms of aroma and texture. Learn more about trimming techniques and comparisons of manual and machine approaches in the article Trimming: Manual vs Machine and How to Do It.

How to tell when material is properly dried

Properly dried material should meet several criteria:

• Stalks of thin branches snap with a characteristic crack, but don't crumble to dust
• The surface is dry to the touch, but the interior still retains slight flexibility
• Trichomes are clearly visible, glossy, and don't break apart from mere touch
• Aroma is pronounced and clean, with no hay or moisture smell

Internal humidity at this point should be approximately 10-12%. Precise measurement is enabled by special moisture meters for plant material, which are more accurate than regular hygrometers measuring air.

Curing: a phase many growers skip

Between drying and long-term storage comes curing, or controlled aging in sealed containers. It's a process in which humidity inside the material redistributes evenly and biochemical changes continue that are responsible for final aroma and taste.

Curing takes place in hermetically sealed glass containers (typically mason jars). In the first week, containers must be opened briefly once or twice daily so air can be exchanged and excess humidity can escape. This process is called burping. If you smell ammonia or excessive humidity after opening the container, leave it open longer or dry the material further.

Optimal humidity in the container during curing is 58-65% RH. This is where humidity regulators come into play.

Boveda and other humidity regulators: how they work and why to use them

Humidity regulators like Boveda are small packets containing a saturated salt solution. They work bidirectionally: if humidity in the container is too high, the packet absorbs it. If it's too low, it releases humidity. They maintain stable RH without any maintenance.

For curing and short-term storage, packets with a 62% RH rating are most commonly used. For long-term storage or those preferring a drier texture, variants with 58% RH exist.

Benefits of using humidity regulators:

• Stable conditions without need for daily monitoring
• Protection of trichomes from mechanical damage caused by over-drying
• Preservation of aromas and terpenes for longer periods
• Reduced risk of mold development with proper use

It's important to check the packets regularly. When Boveda hardens and loses flexibility, it's time to replace it. Used packets cannot be recharged with water – doing so disrupts their chemical balance.

Long-term storage: what determines shelf life

If you want to store material longer than a few weeks, attention to several factors is necessary:

• Humidity: maintain RH between 55-65% using humidity regulators
• Temperature: cooler environment (below 20°C) slows degradation of terpenes and cannabinoids
• Light: UV radiation is one of the main factors in trichome degradation – store in darkness or dark containers
• Oxygen: minimize air contact; vacuum sealing or containers with minimal air space extend shelf life

For long-term storage, glass containers with tight lids stored in a cool, dark place are ideal. Plastic bags are not suitable – they're permeable to air and can affect aroma.

Storage and extraction

If you plan to use the material for extraction, slightly different rules apply. For most extraction methods, having well-dried material is appropriate – ideally below 10% internal humidity. Excess humidity complicates extraction and can negatively affect the final product. Trichomes, however, must remain undamaged, so unnecessary handling and vibrations during storage must be avoided.

Learn more about the entire process from harvest to storage in the article How to Properly Harvest, Dry, and Store Your Crop.

Most common humidity control mistakes

• No hygrometer: estimating humidity by eye is a reliable path to problems
• Too-rapid drying: attempting to shorten the process by raising temperature or forcing ventilation leads to poor quality
• Skipping curing: material may look dried, but without curing it won't reach its full potential
• Inappropriate containers: plastic bags or containers with non-sealing lids are unsuitable for longer storage
• Ignoring odors: ammonia or mustiness are clear signals that something is wrong

Conclusion

Humidity control is not just a technical formality – it's the foundation on which the final quality of your crop rests. From the moment of harvest through drying on a drying net, trimming, curing, to long-term storage, one rule applies: measure, monitor, and respond. Investment in a hygrometer and humidity regulators like Boveda will repay itself many times over in the form of preserved aromas, undamaged trichomes, and material that maintains quality throughout storage.

The care devoted after harvest is just as important as care for the plants themselves. Those who master this phase have a crop that truly matches the effort invested.