Total THC and Harvested Hemp

Confusion over Total THC continues to plague the hemp industry.

We regularly receive calls about hemp compliance, particularly as it relates to Total THC. As I will discuss in this article, the term “Total THC” refers to the delta-9 THC value as determined after the process of decarboxylation. The point of a “Total THC” testing standard is to determine total potential delta-9 THC content in a hemp sample. As explained below, Total THC is derived from the sum of the THC and THCA content on a dry weight basis.For more information about Total THC, click here, here, here, and here.


A casual observer of the hemp industry may be under the impression that the “Total THC issue” was resolved when the USDA published its Final Rule on January 19, 2021, which becomes effective on March 22 and mandates that “[t]he total THC, derived from the sum of the THC and THCA content, shall be determined and reported on a dry weight basis.” However, the Final Rule does not address THC testing for hemp that has been harvested. The USDA only regulates hemp production (ie, cultivation) and its Final Rule only regulates pre-harvested hemp.

What about hemp that has been harvested? Must its Total THC also be within 0.3% on a dry weight basis? This issue is of particular concern for distributors of smokable hemp, which largely consists of the cannabinoid-rich buds/ flowers. These buds and flowers often contain delta-9 THC concentrations well below the 0.3% limit, but Total THC in excess of 0.3%. Are these products lawful? 

Specifically, this article addresses the legal status of hemp which meets the following description:

  • It was deemed to be compliant prior to harvesting pursuant to the testing protocols set forth by the US Department of Agriculture (USDA) and applicable state laws regarding hemp production, and
  • It has been harvested, and
  • It contains delta-9 tetrahydrocannabinol (THC) concentrations that do not exceed 0.3% on a dry weight basis, and
  • Its “Total THC” concentrations exceed 0.3%.

Hemp meeting this description is not a controlled substance under federal law. This is because the so-called “Total THC” standard in the Final Rule only applies to pre-harvested hemp. It does not apply to harvested hemp which was deemed to be compliant prior to harvest pursuant to USDA regulations and applicable state law. The only federal law that applies to harvested hemp is the Farm Bill, which solely takes into consideration concentrations of delta-9 THC, not “Total THC”. Additionally, THC in hemp is not a controlled substance.

Before proceeding, there are two important things to note. First, this article is for informational purposes only. It is not intended to be legal advice and should not be construed as such. Unfortunately, the Total THC issue continues to create a significant amount of confusion and it has not been addressed by any courts. Second, this article addresses federal law. State laws differ. Some states, including Florida and Oregon, regulate and restrict the THC levels in post-harvest hemp. You should consult with an informed attorney and the laws of the state(s) in which you operate prior to engaging in any hemp transactions. 


Hemp initially became exempt from the CSA, and removed from the list of controlled substances, by virtue of the 2014 Farm Act when produced pursuant to a state’s industrial hemp pilot program. Nearly forty (40) states created pilot programs under the 2014 Farm Act. The current Farm Bill, enacted at the end of 2018, expanded the definition of hemp from the prior Farm Bill. The current Farm Bill defines hemp as follows:

(1) HEMP.—The term ‘hemp’ means the plant Cannabis sativa L. and any part of that plant, including the seeds thereof and all derivatives, extracts, cannabinoids, isomers, acids, salts, and salts of isomers, whether growing or not, with a delta-9-tetrahydrocannabinol concentration of not more than 0.3 percent on a dry weight basis. (emphasis added)

The Farm Bill treats hemp as an agricultural commodity, putting it on par with wheat, grain, and soy. Hemp is not a controlled substance under the CSA. Importantly, under the Farm Bill the sole criteria for distinguishing between lawful hemp and unlawful marijuana is the concentrations of delta-9 THC.


Although not found in any federal statute or rule, the phrase “Total THC” is a quasi-legal term that has been adopted by the hemp industry. It refers to the total potential delta-9 THC content in a hemp sample. To determine the total potential delta-9 THC in a sample, the concentrations of tetrahydrocannabolic acid (THCA) must be taken into account. This is because THCA can convert to delta-9 THC in a chemical process called decarboxylation under certain conditions, including when it is subjected to heat. 

Under the USDA Final Rule, a hemp crop is deemed to be compliant (ie, lawful hemp) if it is tested no more than thirty (30) days prior to harvest using a postdecarboxylation method and the results show that the delta-9 THC value does not exceed 0.3% on a dry weight basis. The Final Rule addresses “Postdecarboxylation” as follows:

“Postdecarboxylation. In the context of testing methodologies for THC concentration levels in hemp, means a value determined after the process of decarboxylation that determines the total potential delta-9 tetrahydrocannabinol content derived from the sum of the THC and THC-A content and reported on a dry weight basis. The postdecarboxylation value of THC can be calculated by using a chromatograph technique using heat, gas chromatography, through which THCA is converted from its acid form to its neutral form, THC. Thus, this test calculates the total potential THC in a given sample. The postdecarboxylation value of THC can also be calculated by using a high-performance liquid chromatograph technique, which keeps the THC-A intact, and requires a conversion calculation of that THC-A to calculate total potential THC in a given sample.”

The postdecarboxylation value for THC, as described above, is synonymous with the Total THC in a hemp sample. For this reason, it is clear that a pre-harvested hemp crop is not compliant unless its Total THC concentrations do not exceed 0.3% on a dry weight basis.


Because a pre-harvest hemp crop is only compliant if its Total THC is within the 0.3% limit, many people wrongfully contend that this standard also applies to harvested hemp. However, for the reasons I will discuss, it is clear that this is not the case.

The Total THC requirement (ie, the requirement to use a post-decarboxylation testing method) arises from the USDA’s Final Rule. It is important to keep in mind that the USDA only governs hemp production. It does not regulate hemp that has been harvested nor does it regulate hemp distribution or hemp products. Provided that a pre-harvest hemp crop has been deemed to be compliant under the USDA’s Final Rule, it may be harvested. Thereafter, the USDA has no further jurisdiction over the hemp crop. The only other agency expressly granted authority to regulate hemp under the Farm Bill is the Food and Drug Administration (FDA). The FDA’s authority picks up where the USDA’s drops off, namely, at the post-harvest stage for hemp that is intended for human or animal use. The FDA has not promulgated any rules related to hemp or THC concentrations. The sole authority on post-harvested hemp is the Farm Bill. Its definition of hemp specifically defines hemp in terms of its delta-9 THC concentrations, not its Total THC content.  

The fact that the USDA Final Rule requires a pre-harvested hemp crop to comply with a Total THC standard that does not apply to harvested hemp under the Farm Bill’s definition of hemp has created significant confusion in the hemp market. This is because it is not unusual for a pre-harvested hemp crop with Total THC concentrations that are within the 0.3% limit to result in harvested hemp with Total THC limits that exceed 0.3%. In other words, a compliant pre-harvest hemp crop does not necessarily result in harvested hemp with Total THC concentrations that are within 0.3%. This may appear to be illogical; however, it can be caused by a number of factors.

First, the USDA Final Rule mandates that a hemp sample be taken “approximately five to eight inches from the “main stem” (that includes the leaves and flowers), “terminal bud” (that occurs at the end of a stem), or “central cola” (cut stem that could develop into a bud) of the flowering top of the plant.” This includes plant material, such as the stalk and stems, that contain only minimal concentrations of THC. Cannabinoids, including THC, are primarily concentrated in the hemp plant’s flowering top and buds. The leaves contain some cannabinoids, but they are less concentrated than in the flowering buds. The other parts of the plant do not contain meaningful quantities of cannabinoids. Thus, a hemp plant with flowering buds that have Total THC concentrations in excess of 0.3% can be compliant since the buds are ground up and mixed with other parts of the plant that do not contain THC to form a test sample. In effect, the other parts of the plant dilute the THC concentrations in the bud when the sample is taken, thus resulting in a compliant plant. If the plant is harvested for the purpose of selling the flowering buds then the stalks, stems, and leaves are removed, leaving the portion of the plant with the most concentrated levels of cannabinoids, including THC. Pursuant to the Farm Bill, these buds must not contain delta-9 THC levels that exceed 0.3%; however, they are lawful since they are the post-harvest product of hemp which was deemed to be compliant by the USDA Final Rule and they meet the Farm Bill’s definition of hemp.

Second, the USDA Final Rule provides a thirty (30) day harvest window. This means that a hemp crop must be tested for THC concentrations within thirty days of harvest. During the window of time between testing and harvest a hemp plant’s cannabinoid concentrations, including THC, continue to increase. For this reason, pre-harvest hemp which has been tested and determined to be compliant may have Total THC concentrations that exceed 0.3% when it is finally harvested. Provided that this hemp crop is harvested within the thirty-day window it is lawful.

Third, each hemp plant is unique in terms of its particular traits, including its concentrations of cannabinoids. Pre-harvest testing is mostly randomized in terms of which samples are taken from a crop. Accordingly, it is possible for the particular hemp plants chosen for testing to contain Total THC concentrations within the 0.3% limit while other plants in the same crop to have Total THC concentrations that exceed 0.3%. Since compliance testing is done for the entire crop (which can include a field, a greenhouse, or an indoor growing room) and not per plant, the individual plants within a compliant crop with Total THC concentrations in excess of 0.3% are themselves compliant. This is because they are part of the crop which has been determined to be compliant.

Finally, it is important to note that the CSA expressly provides that “tetrahydrocannabinols in hemp” are not controlled substances. The only form of THC that is referenced by name in the Farm Bill is delta-9 THC. It is lawful in hemp when its concentrations do not exceed 0.3%. All other forms of THC in hemp, including THCA, are expressly removed from the CSA and are not controlled substances regardless of their concentrations. (Note that this also applies to delta-8 THC, but that is a different issue entirely. You can read more about delta-8 THC by clicking here.) 


Harvested hemp which was deemed to be compliant prior to harvest pursuant to the USDA Final Rule and applicable state law is not a controlled substance when its delta-9 THC concentrations are within 0.3% on a dry weight basis, even if its Total THC concentrations exceed 0.3%. This is because the Total THC standard only applies to pre-harvest hemp. With respect to hemp that has been harvested, the Farm Bill provides that the sole distinguishing feature between lawful hemp and unlawful marijuana is the concentrations of delta-9 THC. All other forms of THC in hemp, including THCA, have been removed from the CSA and are irrelevant in determining whether a harvested hemp plant or product is lawful.

March 17, 2021

Rod Kight, Cannabis industry attorney

Rod Kight is an international hemp lawyer. He represents businesses throughout the hemp industry. Additionally, Rod speaks at hemp and cannabis conferences, drafts and presents legislation to foreign governments, is regularly quoted on hemp and cannabis matters in the media, and is the editor of the Kight on Cannabis legal blog, which discusses legal issues affecting the hemp and cannabis industry. You can contact him by clicking here



7 comments on “Total THC and Harvested HempAdd yours →

  1. So. Harvested and cured flower with lets say 6%THCa but 0.3% D9THC is somehow still called Hemp and not Marijuana even though you can find flower just like this in any Marijuana dispensary? That’s hilariously confusing.

    1. Thanks for reading and commenting, Chris. While that is technically possible, it is most likely the case that a harvested plant with 6% THCA would not have been compliant with the USDA’s “total THC” pre-harvest testing requirements. -Rod

  2. It is time our government stop trying to rule over every aspect of our personal lives… Smoking hemp still has the stigma of being a drug user, although the psychoactive high isn’t present… It is a shame that the DEA is being allowed to monitor an agricultural product that so many use on a daily basis… The DEA is a draconian agency that needs to be restructured through cutting their funds by at least half…

  3. I’m very curious as to the legal status of a THCa flower if one smokes or decarboxylates it (I guess to make a hemp edible?). In performing this process you’d end up with much of the THCa converted to delta-9 THC, eventually surpassing the 0.3% limit. I fail to see a scenario in which this wouldn’t be considered a controlled substance at that point – you’d essentially have turned your hemp into marijuana with fire.

    1. Trevor- Good question. Decarboxylating THCa to make an edible product is not recommended since it could cause the concentrations of delta-9 THC in the final product to exceed 0.3%. -Rod

  4. My store just got raided and flower seized. I was arrested and charged with distribution and the only flower I carry is THCA from earthy. Lab reports sent to me from Earthy show under .3 delta 9. However, the detectives sent it to a lab and it’s coming back as actual marijuana with over .3 delta 9. So, can you help me understand how this is possible and I’m in this position?

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