Drying Hemp Outdoors
Among all post-harvest operations, the drying process is arguably the most mission-critical in determining the ultimate quality of the finished product. When hemp is dried cleanly, quickly, and with minimal loss or damage of the product, it maximizes the harvest's quality of the fiber, medicine, and food products.
By contrast, when hemp is dried too slowly or harvested too wet, or with insufficient ventilation, or becomes contaminated or dirty by bacteria or fungi during drying or harvesting it can come unsaleable, spoiled, and completely unsuitable for medical or food processing.
Farmers who want to get started in the hemp industry often end up not adequately planning and preparing their facilities for drying hemp. Depending on budget, resources, and size of the grow, many farmers have to go the method of drying outdoors in the field versus buying hemp drying equipment.
Drying In The Field. The Natural Approach.
Drying in the field is deceptively less labor intensive but leaves a lot to chance (even if uncertainties can be minimized with sufficient knowledge, it’s never a sure thing and drying may be inconsistent, especially on dual variety farms).
This method is often used prior to tough-harvesting of hemp flowers to reduce the amount of time required to batch dry after trimming or combining has been completed. Allowing the hemp plant to dry naturally on its own can be useful when desiring to jumpstart the curing process.
Determine Moisture Content
Hemp is always harvested at a higher moisture content than what is considered safe for storage. This is done to mitigate the risk of crop loss that may occur from plants that shatter because they're too dry. It is recommended that farmers test the overall moisture content of the crop prior to harvest. This will help to determine whether immediate drying is necessary or waiting longer is an option.
The industry has agreed upon a 10% moisture level for hemp to qualify as dry. However, because hemp destined for the marketplace can sit in storage for as much as 1-2 years before being shipped out for processing, many processors require storage moisture levels closer to 8-9%. It is best to consult the processor well in advance of harvest to ascertain what they consider safe for long-term storage.
Dry Until Stems Split When Bent
Leave hemp plants hanging on the line for 3-10 days until stems begin to split when bent. This will serve as a cue that the plants are dry enough to be trimmed.
Do not allow stems to become so dry that they snap under pressure as this can lead to the loss or damage of trichomes as they will be more susceptible to flaking when casually brushed or carelessly handled.
Length of Drying Period
The exact during will depend on several factors including heat and sunlight exposure nearing the time of harvest, as well as the size of the buds to be dried. Generally speaking, roughly 2-5 days will be needed to dry, but it is imperative that you flip the plans each day and monitor them regularly.
If the plants begin to fully brown, they may be over dried. This is why flipping and rotating on a regular basis during high heat conditions can mitigate risk of drying out.
Conversely, if the plants do not dry quick enough, you run the risk of mold and mildew. For these reasons, you'll have to check the upcoming weather forecast to make sure there is sunlight and warm weather on the horizon. If rain is in the forecast, it may be wise to wait until it passes before cutting down the plants (so long as you don't run the risk of the plants going over the legal THC limit).
Outsourcing Drying Operations
For new and small-scale farmers who do not yet have on-site facilities required for large scale hemp production or those that do not want to risk issues of outdoor drying, there is the option of investing in hemp drying services. These services often tend to be highly regional because of the need to get crops to a facility within 2 hours of cutting them down.