THC in hemp…time to dispel a huge myth.

All hemp is cannabis. Not all cannabis is hemp. What is the difference? You can’t tell by looking or smelling. You can tell by smoking…if you get high then it isn’t hemp. There is where the difference lies…hemp, by definition has less than 0.3% THC. There is no limit on the other cannabinoids, in fact we want them sky high!

The difference between marijuana and hemp then is not a natural one, but a legal definition assigned by the government. In the United States hemp must have a total THC of under 0.3%. ” Total THC” means “the molar sum of delta-9 THC and THCA [tetrahydrocannabinolic acid].”  In the European Union the number is 0.2%.  In practice, at least in Oregon where we grow hemp, you are allowed up 0.35% total THC to allow for testing errors.

So here is a picture of cannabis that I really hope tests as hemp when flowering begins.

You see, it is not actually hemp until it has gone through a Compliance Test by a 3rd party laboratory.  The grower submits a written request for a compliance test to an accredited laboratory. The lab sends a technician out at the appointed time who fills out a “Chain of Custody” document with the grower and then proceeds to sample the field.  When the lab finishes its test, the results are emailed to the Oregon Department of Agriculture. At the moment the ODA signs off on the compliance test, the cannabis in the field magically transforms into hemp.

For compliance sampling to proceed the field must be in the early flowering stage like this:

After the compliance testing is completed, in 2020 we have 28 days to complete the harvest. If we don’t meet the 28 day window for harvest, we must compliance test again.

Next year the harvest window is going to be cut in half to 14 days. This is a very big deal because you want to test early enough that there is a very low probability of “going hot”. “Going hot” means having a THC level that exceeds the total legal limit. That is the worst thing that can happen to a hemp grower. If your compliance test comes back above the legal limit your crop must be destroyed. Starting next year, a hot compliance test must be forwarded to the federal Drug Enforcement Agency…so really a grower needs to not go hot.

So this is where “The Myth” I referred to in the title comes into play. Because cannabis has been illegal for decades and listed as a schedule 1 narcotic, very little research has been done into how cannabis grows. People were putting out their best guesses as to how and why a hemp plant goes hot. While the intentions were good, the guesses based on almost no data turned out to be bad.

The guess that seemed to be most plausible and gained traction was that “CBD develops first and then after CBD peaks THC starts to rise.” Several scientists, including my friend Clint Shock put that myth to rest last year

What really happens is that the genetics of the plant determines a set ratio of CBD:THC, and both CBD and THC develop at the same time. In fact, Dr Shock has made the case to the USDA that the definition of hemp needs to be changed from 0.3% or less THC to cannabis having a minimum of a 20:1 CBD:THC ratio. In other words if you have 20% CBD you will have 1% THC. 1% THC isn’t going to get you high, especially with 20% CBD which interacts with THC in the body to reduce the psychoactive effects of THC.

Clint’s research at his facility in Ontario, Oregon last year which he released on  November 22, 2019 in a report titled: “Hemp and its regulation: the small background of THC in CBD hemp” At this point I am just going to copy and paste from Clint’s document so I do not change his meaning:

He starts by describing how the new USDA Draft rules will cripple the nascent hemp CBD industry and offers this solution:  “The potentially detrimental USDA policies can easily be averted by the
following: 1. For hemp flowers with greater than 6% CBD, edit the 0.30 % total THC rule to permit hemp flowers grown for CBD that have a ratio of 20:1 or more of total CBD to total THC, regardless of the THC content. 2. Allow growers six weeks to harvest their crops after approved sampling for potency.”

Here is the abstract of his research:

In 2019 we grew thousands of genetically different CBD hemp (Cannabis sativa) plants as part of our breeding and selection program to create and identify lines of hemp beneficial for
growers. Plants were grown in Ontario, Oregon. Between September 23 and 29 we sampled flowers from 273 unique hemp plants. All the germplasm tested had been designed to provide CBD. The 273 samples were submitted to laboratory analysis along with 5 check samples from the same field with known cannabinoid content. The 278 samples were analyzed for cannabinoids by Integrity Labs, LLC, 2747 Pacific Ave SE B21, Olympia, WA 98501 (WA State
I502 Certification #09). The results were used to evaluate the amounts of CBD, THC, and other cannabinoids that can be expected in CBD hemp. Repeated weekly flower samples were taken
from 28 clones, submitted to Integrity Labs, and data from one clone is presented to show the trends over time of total CBD, total THC, and the ratio of total CBD to total THC.

I have heavily edited Clint’s results to just the parts that dispel the myth of ‘CBD develops and peaks 1st, then THC starts to develop. The emphasis was added by me.

No Delta 9 THC was detected in any of the 278 flower samples (Figure 1). A low background of THC was detected in all of the flower samples. The background THC concentration increased with the CBD concentration. The ratios of total CBD to total THC ranged from 22.4:1 to 32.1:1 among this set of germplasm The ratio of total CBD to total THC was not enhanced by early harvests. Due to the relative stability of the ratio of total CBD to total THC over time, there is no point in restricting growers to a narrow harvest interval following potency testing.

My data from last years crop lines up nicely with Clint’s:

9/23/19     THC=ND    CBD = 1.82%…compliance test

10/04/19   THC=0.15  CBD = 4.49…preharvest potency test of buds

10/23/19   THC=0.34%   CBD = 9.88%..preharvest potency test

11/25/19   THC=0.49%  CBD = 13.18%  post harvest flower buds

11/25/19   THC=0.23%  CBD = 6.8%  post harvest biomass (all buds + leaf)

02/27/20  THC=2.52%  CBD = 59.8% filtered and decarbed crude after extraction

You can see from my test data that THC developed at the same time as CBD and the ratios stayed in a tight range of 27:1 – 30:1, that carried through to the extracted crude oil as well.

So the data clearly shows that THC and CBD develop concurrently, not separately. Additionally, the data shows that the CBD:THC ratio is set by genetics and varies little over the lifespan of the plant. Unfortunately some writers have published the myth of CBD 1st then THC later. Even presented with the science on multiple occasions they refuse to update their knowledge to match the current science.

All hemp is low THC, both by definition and by genetics. By politics and by science. Breeders are pushing hard to increase the ratio which is typically in the range of 25:1 to 40:1. Some breeders are claiming 50:1 or higher, but I am skeptical until I see independent data.

The new darling of the industry is CBG rich cannabis. CBG plants have an even higher ratio than CBD plants…80:1 CBG:THC and higher. This higher ratio makes it easier for the grower to stay legal while still producing enough CBG to profitably extract.


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