What's in the stems?

We have all heard the rumors regarding marijuana stems. Some say they do not contain any cannabinoids, some say they do. We decided to investigate. We took three very different stem samples and ran an analysis using HPLC-UV.



Our first stem sample was from my personal stem jar. Many people save their stems for one reason or another. The stems in this jar had come from various high-quality strains, and they had been previously sifted over a screen to harvest the kief. A portion was parsed out of the jar and processed using the same procedures and methods as a typical cannabinoid profile. These stems had a Max THC of 1.2%. There was no CBD and 0.1% of CBN.

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The second stem sample came from flowers that had been pollinated. The sample was prepared in the same manner as the previous one, and the results were very similar. The Max THC was 1.1%, and there were no other cannabinoids found.


The third stem sample came from flowers that we had previously tested. The tested flowers had a Max THC of 18.3%, which is higher than average. We expected these stems to measure similarly to the previous two samples. We were surprised to see that the Max THC of these stems measured out to 9.2%, which is higher than many bud samples that we’ve tested.

sour diesel comparison stem and bud

We will be conducting tests on more samples to get a better understanding of what to expect in the stems, however these results show us that not all stems are created equal. Just like the variance we see in flower and concentrate samples, stems can have varying levels of potency. When trying to make some sense of these numbers, consider this: one gram of stems from the third sample has about 80 more mg’s of THC than one gram of stems from the first two samples. Think twice before throwing your stems away next time.

comparing stems

What I Learned About my Dirty Bowl

What I Learned About
My Dirty Bowl

(What's in the resin?)


Anyone who researches as part of their job can relate to this – all of sudden you are reading an article you stumbled across while you were looking for something entirely different.  It catches your eye, you click, scan, click again and you don’t even remember what you were looking for.  This accidental find triggers something in you that starts you off on a new adventure you might not have ever thought of.


My adventure was to perform a chemical analysis of resin scraped from my glass bowl.  I remember in my youth having occasions where I wanted to smoke a bowl but did not have a supply of bud. Of course I had been introduced to scraping resin from a bowl to smoke at some point by one of my friends and would resort to that in a pinch. Thinking back on those bowls of reclaimed resin, I recall getting a sub-par buzz, not like a nice juicy bud kind of high.


After getting pulled into an article by High Times Magazine titled ‘5 Signs You're Are Smoking Too Much Marijuana’ by Russ Belville, which recommends not smoking these resin scrapings, I decided I had to find out what was in those bowls of resin scrapings from my youth. After all, I am a research scientist specializing in cannabis and I have my own accredited cannabis testing laboratory. Curiosity drives much of what I do.

I cleaned my bowl with a small metal knife carefully collecting the resin.  My bowl was really overdue for a cleaning by the way.  I carefully weighed about 140 mg of resin into a collection tube and performed our standard validated cannabinoid profile analysis on the resin and ash.  After processing the data I have to admit I am very surprised by the results.  Almost 15% by weight consisted of cannabinoids!


Full disclosure - this analysis only looks for the presence and amount of six cannabinoids - THC, d8 THC, CBD, CBN, THCa, and CBDa. It does not inform what other compounds are present.  Combustion of plant material results in the formation of hazardous chemicals and intentionally ingesting the residue resulting from this combustion is likely not favorable to good health.

I agree that smoking bowl scrapings is pretty desperate, not something you should do, and not as good as smoking proper cannabis products.  This makes the results all the more surprising. I guess it must be the elevated CBN dragging down the experience(CBN is known to cause drowsiness) but with a THC max of just over 12% I have to admit these results are unexpected.


So hopefully someone out there has always wanted to know and now you do.  My curiosity is temporarily satisfied, but if you have an idea for an experiment, drop me a line at [email protected] and if I can make it happen (no guarantees) I will.

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