Hemp growers and processors do a delicate dance in their attempts to create retail CBD products that do not run afoul of federal regulations regarding THC. A big part of that dance is determining when to harvest plant material in order to maximize CBD extraction. Has science now revealed the best time to do so? Perhaps.
A team of British and Thai researchers believe they have determined the optimal harvest point for hemp plants based on studying the chemical compounds in cannabis and how they present at various points in plant growth. Remarkably, they discovered that cannabinoid levels do not remain constant in all parts of the plant and at all stages of growth.
Their research could prove vitally important for the simple fact that hemp extraction equipment cannot differentiate between growth stages. Extraction processes are static regardless of when plants are harvested. So to make life as easy as possible on processors, you ideally want to harvest plant material at the point where it yields the maximum amount of CBD without illegal levels of THC.
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The Two Big Cannabinoids
If you know anything about cannabis, you know that CBD and THC are the two big cannabinoids that processes are interested in. Growers tend to emphasize one cannabinoid over the other in their plants. When CBD is dominant, the goal is to keep THC below the 0.3% threshold for hemp. When THC is dominant, growers purposely exceed the 0.3% threshold to produce cannabis plants.
Again, hemp extraction equipment is agnostic in this regard. When CedarStone Industry, out of Houston, TX, sells extraction equipment to a processor, they expect the processor to know everything they need to know about CBD and THC. Assuming they do, they will seek to buy either hemp or cannabis plants based on the cannabinoids they want to focus on.
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What the Research Found
Researchers discovered that cannabinoids and terpenes continually increase in the tops of cannabis plants until they start flowering. From there, levels tend to decrease until seed maturity is realized. Interestingly, levels of CBD and THC differ at the point a plant first buds. That is when CBD is at its highest point. Meanwhile, THC can be present at levels up to 63% lower than CBD.
In a nutshell, the best time to harvest industrial hemp plants to maximize CBD and minimize THC is just when the plants start to bud. Researchers also say that the tops of the plants could be harvested at that time while the plants themselves are otherwise left intact for later harvest. A secondary harvest could be used to obtain phytosterols and waxes found in the leaves.
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Fewer Hot Plants
The research could ultimately prove invaluable to growers and processors who have to work hard to avoid hot plants. A hot plant is one with a THC content that inadvertently rises above the 0.3% THC threshold. By the letter of the law, hot plants must be destroyed unless a grower has a state license to grow cannabis.
In the processing center, plant material can temporarily go hot during hemp extraction. Whether or not that material has to be discarded is not clear. One way or the other though, any finished products sold by the processor must contain less than 0.3% THC to not be considered cannabis.
Here’s hoping future research verifies this latest study. If so, knowing the best time to harvest hemp and extract CBD could help growers and processors considerably. It could help them both maximize CBD and avoid hot plants that could otherwise get them in trouble. Both are very good things for the industry.