Top-down tray drying vs hang drying: what is the difference?

In the cannabis industry, a lot of attention is put on the cultivation process, as growers must produce high-quality products to stand out in such a highly competitive market. There is the possibility, however, that the focus on maximizing the quantity of the yield might lead to growers overlooking other equally important processes, such as drying. Properly drying and curing the cannabis is the very last, crucial step of the journey of a cannabis plant, and failing to deliver in this phase can have very serious repercussions on the quality of the end-product. “There are a lot of developments with regards to irrigation, lighting, substrates, and climate,” Nick Abbingh with Cannabis-Drying.com says. “At the same time, the post-harvest processing is often overlooked and rushed. The issue is that doing this is literally like tripping at the finish line. The consequence of this for the cannabis operation can be quite significant.”

Top-down tray drying vs hang drying
So, while on the one hand, it is necessary to pay more attention to the whole post-harvest world, it is also necessary to further study this process to find the best practices to eventually achieve some degree of standardization. “A lot of master growers in the cannabis market believe that drying the whole cannabis plant, or stems of the plants, results in a better retention of cannabinoids and terpenes compared to when the flowers are dried in a tray,” Nick explains. “One of our customers wanted to switch from hang drying to tray drying, because it is way more space-efficient, and wanted to find out if these beliefs were true. Thus, we conducted a test where we compared the traditional hang-drying method with a unit from Cannabis-Drying.com.”

Cannabis-Drying.com developed a special testing unit, where the flowers of the plants are placed in specially designed Canna-Trays. “The Canna-Trays are placed on a ventilation pallet and a ventilator sucks the air top-down through the trays filled with cannabis,” Nick continues. To conduct the test, the drying unit and the hanging racks were placed in the same controlled-atmosphere room, so that the drying would be carried out under the same conditions for both methodologies. “One of the goals of this study was to find out if there were any differences in cannabinoid and terpene content between Cannabis-Drying.com’s unit and the hanging racks,” Nick points out. “The hypothesis that they were following was that there should be no differences in cannabinoid and terpene content.”

The controlled atmosphere room where the drying unit and racks were placed had a set temperature of 18.3 degrees Celsius, with a relative humidity set at 55%. The drying racks could fit 20 plants in, the yield of which is 45 grams per plant on average – after drying and trimming. For the first test, 95 bucked plants of ‘Cannabis Strain 1’ could fit in the Cannabis-Drying.com’s unit. For the second test, two strains were put in the unit and racks: ‘Cannabis Strain 2’ and ‘Cannabis Strain 3’; 225 bucked plants could fit in the Cannabis-Drying.com system. The drying rack took 7 days to dry the cannabis plants in both of the tests, while the drying unit took 7 days for the first and 6 days for the second. Eventually, 10 samples were taken from both of the treatments and got analyzed by a lab to determine terpene and cannabinoid content. The results showed that Cannabis-Drying.com’s drying method is comparable with the conventional hanging method with regards to the terpene and cannabinoid content. Yet, further research is necessary to better understand cultivar-specific differences.

Lab analyses and takeaways
“Lab analyses showed that there are no major differences in the end-quality of the cannabis for both drying methodologies,” Nick explains. “The benefit of our Top-down system is that it is way more space-efficient and allows for greater control over the drying process. In this experiment, 225 bucked plants were placed the test unit, the equivalent of 12 drying racks with hanging plants, resulting in a space-efficiency of 83%. In a trial that was conducted later, 372 bucked plants were placed in Cannabis-Drying.com’s unit, the same amount as 19 drying racks, making the test unit 89% more efficient. In an earlier trial, that was conducted at a Dutch university, the Canna-Trays were filled with wet trimmed cannabis. 200 grams of wet trimmed cannabis could be placed in one Canna-Tray, comparing this to the racks with hanging plants would give a space-efficiency of 96%.

The Cannabis-drying.com system also makes sure that each part of the cannabis receives the same amount of airflow, resulting in an evenly dried product. Wet spots on the cannabis won’t emerge, because of the evenly distributed air, giving mold and bacteria no chance to emerge on the wet spots. The fact that the air is filtered before and after it comes in contact with the cannabis makes sure that the cannabis is dried with clean air and that there is less contamination in the drying cell. All in all, Cannabis-drying.com’s drying methods are way more space-efficient, offer better internal logistics and does this without the loss of cannabis components compared to the conventional hanging method.”

The official research report can be seen here