How To Increase CBD Yield While Keeping THC Levels Down: Cannabis Science Has Answers

As demand for CBD grows, farmers are looking for ways to maximize their yield. Is there a way to do that? Enters science.

According to a new study published in the journal Royal Society Open Science, there is a way to grow cannabis for maximum CBD yield. A collaborative project between Khon Kaen University in Thailand and the University of York in the U.K., noted the booming demand for cannabinoids, highlighting that the global market is projected to hit $9.69 billion by 2025.

"CBD distillate sells for $3,000 per kg, while CBD isolate sells for $1,000 per kg," co-author Andrew Hunt, from Thailand's Khon Kaen University told Newsweek.

What makes maximization of CBD yield more complicated is the presence of THC compound, that needs to stay under certain levels, as its illegal in many countries.

"In the USA, the legal THC concentration limit cannot exceed 0.3 percent on a dry weight basis in any parts of the plant, seeds or extracts," said Hunt.

Scientists proceeded to look into how chemical composition changes in hemp at different harvesting times, maximizing the crop’s value industrially, without increasing the level of THC.

The research revealed that a growing cannabis plant undergoes significant compositional transformations in three different compound classes: essential oils, cannabinoids and lipids. It turns out, essential oils and cannabinoids increase in the tops of plants (inflorescencess) until full flowering in the third harvest, before decreasing at seed maturity in the final harvest.

"Initially, as hemp grows, the levels of cannabinoids are low until the plant reaches flowering," Hunt said. "Cannabinoid content then decreases until seed maturity is reached. The greatest proportion of cannabidiol was extracted from the tops at full flowering, however a significant increase (63%) in the banned psychoactive tetrahydrocannabinol (THC) was observed at this harvest stage as compared to the budding stage of development, where the plant initial begins flowering.”

As per the research, harvesting the tops after budding would be preferable due to the high cannabidiol content and low THC.

“Although the highest quantity of CBD was found in the third week of harvest, the best CBD:THC ratio was seen after the second harvest, with quantities of THC being significantly lower than at the third harvest—this would make isolation and purification of CBD much easier.”

The study may come in handy for cannabis farmers who are looking for ways to boost CBD yield while maintaining low levels of THC as required by law.

Photo: Courtesy of Canvast Supply Co. on Unsplash