Cannabis post-harvest: Grower's guide to avoiding mold

One of the biggest issues in cannabis cultivation is mold. Even a minor presence of mold can disqualify medical cannabis from distribution and cause recalls in adult-use buds. While regulations differ from place to place, mold poses a regulatory problem everywhere cannabis is grown legally.

Mold can develop during any stage of cannabis production. From the vegetative phase, through flowering, and even post-harvest, during drying and curing or packaging.

The only way to completely ensure a mold-free cannabis product is by maintaining low humidity. It’s important to control humidity in all stages. Including the grow room or greenhouse, as well as post-harvest, in the drying space and packaging area.

The importance of the cannabis post-harvest process 
The post-harvest process is highly important in cannabis production. Post-harvest processes include trimming, drying, and curing. Once the post-harvest process is complete, the dried and cured cannabis buds are packaged for consumers and patients. Some cannabis plants are used to produce other products, such as edibles, topicals, or concentrates.

Curing and drying plants are highly important, especially when growing high-quality buds for consumption. When done right, these processes ensure the cannabis retains its cannabinoids and terpenes. Both play a part in providing the medicinal benefits of cannabis, as well as the aroma and flavor. Besides maintaining the plants’ properties, proper post-harvest treatment plays an important role in preventing mold.

How mold develops in cannabis production 
The most common types of molds associated with cannabis are gray mold (aka bud rot or botrytis) and powdery mildew. Both mildews can only break out in humid conditions and may develop during any stage of cannabis production.

Drying cannabis is especially important when it comes to mold prevention. Packaging cannabis flower with too high a moisture content can lead to mold development in the packages themselves. This is especially problematic, as buds can stay in their packages for months before reaching the consumers.

Additionally, the mold won’t be discovered until it reaches the consumer. That means extensive recalls and quite a bit of bad press for the grower.

In countries and territories where GMP regulations are enforced, there’s a legal limit on final buds’ moisture content – 8-12%. Cannabis products with a higher moisture content can’t be legally distributed or sold.

How to dry cannabis post-harvest 
There are several drying methods for cannabis, each with their own pros and cons. Some are more complex, like freeze drying, while others are more straightforward, such as hang drying and drying on racks. In both cases, it’s important for the space to be low humidity. Otherwise, growers run the risk of mold development.

Creating and maintaining low humidity conditions for cannabis drying is most commonly done with dehumidification. Dehumidifiers like the DG-X are designed and engineered specifically to create the ideal conditions for cannabis, including drying rooms. These dehumidifiers are highly effective and very efficient at their task. They’re made to remove massive amounts of moisture from the air at a low energy cost.

Ideal post-harvest conditions for cannabis 
Creating the optimal conditions for cannabis during post-harvest is simple when using dehumidifiers. They let growers fully control their space, optimizing conditions to produce the highest quality buds.

The ideal conditions for cannabis post-harvest:

  • Relative humidity levels of 50-60%
  • Room temperatures of 60-68°F (15-20°C)
  • No direct light
  • Air circulation for homogeneous conditions

For more information:
DryGair Energies 


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