Watch the episode · 5:35Hardly any THC hides in a cannabis seed, and that's exactly the problem. From 11 December 2026, a new US law changes how cannabis seeds are judged. Until now, a seed could count as hemp if the seed itself tested at 0.3% THC or less. Now the law looks at the plant it came from. So how much THC is really in a seed, where does it hide, and why did testing the seed stop making sense?
Source · P.L. 119-37, Div. B, sec. 781; P.L. 119-103
The short answer ▶ 0:32
| The seed | Its parent | |
|---|---|---|
| Makes THC? | No | Yes, in its resin glands |
| THC level | Far under 0.3% | Drug type: far over 0.3% |
A seed doesn't make THC itself. It carries a trace, and even seeds from drug-type plants test far under the 0.3% line. Where that trace comes from was shown by one simple lab trick.
Source · Ross, Mehmedic, Murphy & ElSohly, J. Anal. Toxicol. (2000)
Look closely at seeds on a ripe plant. Each one grows wrapped in a small green leaf called a bract, and on a female flower the bracts are covered in resin glands.
THC's acid form is made inside those resin glands (see how a trichome works). The seed itself has none. So whatever THC a seed carries, it didn't make.
Source · Livingston et al., Plant J. (2020)
Where the THC sits ▶ 1:10
In 2000, a team at the University of Mississippi measured the THC in seeds from drug-type plants and from hemp. The drug-type seeds held 36 to 124 micrograms of THC per gram (µg/g). The hemp seeds held 0 to 12.
Source · Ross, Mehmedic, Murphy & ElSohly, J. Anal. Toxicol. (2000)
That sounds like a lot until you convert it: 124 µg/g is 0.0124%. So the highest drug-type seed in the study was still about 24 times under the 0.3% line.
Then came the trick. The researchers gave whole seeds one quick rinse in a solvent, and that single wash removed about 90% of the THC. Washed drug-type seeds dropped under 10 µg/g.
- Shell
- most of the THC, on the outside
- Kernel
- under 2 µg/g (drug type)
- Embryo
- the living plant inside
Then they split seeds open. Most of the THC was in the shell, mainly on its outside. The kernel, with the living embryo inside, held under 2 µg/g in drug-type seeds and under 0.5 µg/g in hemp. That's over 1,000 times under the line.
Source · Ross, Mehmedic, Murphy & ElSohly, J. Anal. Toxicol. (2000)
So the seed doesn't make THC. It picks it up. Resin from the glands on the bract coats the shell as the flower ripens, and more rubs on at harvest, when seed heads are threshed. The authors put the swings between batches down to how dirty the outside of the seeds was.
Why lab results vary ▶ 2:28
In 2017, a Toronto team tested three brands of hemp seed sold as food. Canada allows 10 µg/g of THC. Some results came in up to about 12 times that, and the same brand gave very different numbers depending on how the THC was extracted. The authors couldn't say whether it was contamination.
Source · Yang et al., Cannabis Cannabinoid Res. (2017)
A 2024 study of 29 hemp varieties found THC in just five of them. The highest: 163 µg/g.
Source · Arango et al., Foods (2024)
Put them side by side, in micrograms per gram. A drug-type seed: 124. Food hemp seed: 125. The highest hemp variety: 163. And the 0.3% line? 3,000.
Source · Ross et al. (2000); Yang et al. (2017); Arango et al. (2024)
Drug-type seeds did carry more, about ten times more in that first study. But every result, from every study, sits far under 0.3%. So testing a seed against that line can't tell hemp genetics from drug-type genetics. Both pass.
What the new law changes ▶ 3:35
The 0.3% line was written for the plant (the story is in hemp vs marijuana). In 2022, the DEA said in a letter that a seed counted as hemp if the seed itself tested at 0.3% delta-9 THC or less. As the studies above show, nearly every seed does.
Source · DEA letter to S. Pennington, 21 Jan 2022
The new law, section 781, changes that. In the law's words, hemp no longer includes "any viable seeds from a Cannabis sativa L. plant that exceeds a total tetrahydrocannabinols concentration (including tetrahydrocannabinolic acid) of 0.3 percent in the plant on a dry weight basis". Viable just means able to sprout.
Source · P.L. 119-37, Div. B, sec. 781
| Until 11 dec | From 11 dec 2026 | |
|---|---|---|
| What's tested | The seed | The parent plant |
| Drug-type seed | Usually passed | Not hemp |
| Fibre & grain hemp | Hemp | Still hemp |
So the test moves from the seed to the plant it came from. Seeds from drug-type plants passed the old test easily, for the reasons above. Under the new wording, they're not hemp. Seed from fibre and grain hemp is still hemp.
Scientifically, it fits what the studies show. A seed's THC is mostly residue on its shell, so it says little about the plant inside. What that plant will make once it flowers comes from the genes it inherited from its parents.
As of 12 November 2026, the rule takes effect on 11 December 2026. Congress has already delayed it once, and bills to delay it again or repeal it are sitting in committee. This isn't legal advice: state laws, and other countries, differ, so check yours.
Source · P.L. 119-37, Div. B, sec. 781; P.L. 119-103
A seed makes no THC of its own. What it carries is mostly residue on the shell, and even seeds from drug-type plants test far under the line. That's why, from 11 December 2026, the US judges a seed by its parents.
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Sources
- Ross, S.A., Mehmedic, Z., Murphy, T.P. & ElSohly, M.A. (2000). "GC-MS analysis of the total delta9-THC content of both drug- and fiber-type cannabis seeds." Journal of Analytical Toxicology 24(8): 715-717. doi:10.1093/jat/24.8.715
- Yang, Y., Lewis, M.M., Bello, A.M., Wasilewski, E., Clarke, H.A. & Kotra, L.P. (2017). "Cannabis sativa (Hemp) Seeds, Δ9-Tetrahydrocannabinol, and Potential Overdose." Cannabis and Cannabinoid Research 2(1): 274-281. doi:10.1089/can.2017.0040
- Arango, S. et al. (2024). "Chemical Characterization of 29 Industrial Hempseed (Cannabis sativa L.) Varieties." Foods 13(2): 210. doi:10.3390/foods13020210
- Livingston, S.J. et al. (2020). "Cannabis glandular trichomes alter morphology and metabolite content during flower maturation." The Plant Journal 101(1): 37-56. doi:10.1111/tpj.14516
- US Public Law 119-37 (12 Nov 2025), Division B, sec. 781 (new hemp definition, 7 U.S.C. 1639o), seed clause: "any viable seeds from a Cannabis sativa L. plant that exceeds a total tetrahydrocannabinols concentration (including tetrahydrocannabinolic acid) of 0.3 percent in the plant on a dry weight basis". US Public Law 119-103 (2 Sep 2026), sec. 2019 (delay to 11 Dec 2026). Text: govinfo.gov
- DEA letter to S. Pennington on cannabis seeds (21 January 2022).
Every claim in this article comes from the episode script, which is checked against these papers. Prices on Seedscanner are dated observations; this page is not growing or legal advice.
