Drying Hemp for CBD Production

Harvesting hemp is a critical stage for CBD production. The presence of molds and mildews will lower the value of hemp floral biomass, so a timely harvest is essential.

There are visual clues on the hemp bud that growers should monitor. When trichomes on the hemp bud shift from white to milky white it may be time to harvest. Weekly testing of CBD content can inform the grower of when harvest should be initiated. This is in addition to required THC testing.

While some of the tests for CBD, cannabinoids, terpenes, pesticide residue, mold, and heavy metals can be significant, growers need to test frequently to make the right decision regarding harvest timing. Growers will have an easier time drying and curing their hemp floral biomass if they can bring it in before the arrival of a storm. This is the time when adequate labor is crucial. The vast majority of hemp growers for the CBD market are relying on labor to cut the stalk and load the biomass. This takes a lot of time and physical exertion. There are reports of growers that had an excellent crop of hemp floral biomass but suffered massive losses because they could not harvest it in time. The importance of measuring the labor requirement is a big reason why we recommend that first-year hemp growers for the CBD market start with 1 acre or less. Drying and Curing Hemp

Once hemp is harvested growers should immediately move the floral biomass to the drying facility. The facility should be under roof, out of direct sunlight and well ventilated. Growers need to set up several fans and have them blowing continuously. Significant ventilation is crucial! Ideal temperatures for drying and curing are 60 to 70 degrees F at 60% humidity. Some processors say that hemp growers should not dry their floral biomass at the same temperatures as flu-cured tobacco. Those temps are too high and dry the hemp too quickly. A slow drying with high airflow will cure the hemp, produce a higher quality end product (better cannabinoid and terpene spectrum), and command a higher price.

It is difficult to estimate the square footage of drying space needed per plant. Using a flu-cured tobacco with 800 square feet a grower was able to dry 1 acre worth of plants (approximately 1350 plants) in 3 days. Another grower was able to dry approximately 1.5 acres worth of hemp (plant number not stated) in a 2500 square foot barn. Hanging entire plants upside down on wires in the drying barn is a common practice. Unfortunately, as those plants dry the branches droop down in the formation of a closing umbrella. That closing umbrella shape results in less airflow to the center of that entire hemp plant. Thus more mold and mildew will grow in that center portion. We advise growers to break off the individual branches from the hemp plant and hang branches on the drying wire, not whole plants. This step is more labor intensive but will help minimize mold and mildew.