It’s fun to joke around that your parents simply couldn’t handle their weed back in the day, but it turns out they’re right about today’s strong medical cannabis strains. Potency has more than tripled since the herb became popular, and is continuing to push the limits as cultivation technology improves.
Older folks often make a point to tell you that today’s medical marijuana is much stronger than what they smoked back in the day—even bordering on psychedelic. Believe it or not, this has been verified multiple times over. It’s even prompted calls for government-imposed THC limits. The results may still surprise you, as scientists have uncovered more interesting facts about the recent history of cannabis and rise in potency.
It’s still difficult to determine the exact numbers behind the potency shift, since most of the cannabis industry’s activities have taken place underground. From what researchers can tell, the main psychoactive compound in cannabis, delta-9-tetrahydrocannabinol (THC), used to hang around 1 to 4 percent of total cannabinoid content in the 1970s. Now, the average is more like 13 percent, but in sophisticated markets like Colorado, Washington, and California, you can easily find flowers well above 30 percent THC potency.
Today’s flowers are also mostly hybridized strains. Cross-bred specifically for greater levels of potency and terpenoid content, almost every potent strain on the market these days is a hybrid of some kind. The rich terpene profiles of some plants have therapeutic properties on their own, perhaps not increasing the actual potency of the flower, but certainly increasing your perception of a super dank strain.
Potency of cannabis began to spike in the 1980s alongside the development of hydroponic systems. This technology allowed people to grow their own cannabis plants at home, and savvy growers quickly learned the secrets of lighting, irrigation, and nutrients, creating ideal standards for the industry well before the push for legalization began. As soon as the Internet became a viable communication tool, the modern cannabis movement was born. By going online, cultivators and sellers could find and share the latest and most potent strategies quickly and easily, exposing the world to fresh new high-THC strains.
Cannabinoid ratios are another distinct area where today’s cannabis plants differ from their hippie ancestors. While the level of CBD has not increased noticeably over time, the ratio to THC used to be much closer. Strains with higher levels of CBD actually used to be quite common, phasing out in popularity on the streets only because they offered little psychoactive effect to the user. Only in the last decade have the healing and neuroprotective powers of cannabidiol been discovered. Because of their efficacy for treating seizure disorders and other illnesses, rare strains like Harlequin are once again in high demand, making a comeback after a long hiatus.
Aside from the increase in THC, the look, feel and smell of the cannabis flower has also changed a bit since your parents enjoyed their first toke. From the 1960s to the 80s, most street weed was full of stems, seeds, and leaves. Honestly, it was probably a bit of a stretch to call it a “flower.” The full, perfectly formed hairy nugs of today, with their rich colors and frosty trichome tips, can be somewhat alarming for older consumers just getting back into the weed game.
The moral of the story is to take it easy on your parents and grandparents should they ask for suggestions or help with cannabis. As educated consumers, it is our job to guide others through their own positive experiences.
It’s true, today’s weed is much stronger than what Pops was toking on in the ’70s.
Was Marijuana Really Less Potent in the 1960s?
How incomplete government data encourages a pervasive pot myth
One of the strongest known strains of marijuana in the world is called Bruce Banner #3, a reference to the comic-book scientist whose alter ego is the Hulk. This is probably an appropriate nickname. With a THC concentration of 28 percent—THC is one of the key chemicals in marijuana—Bruce Banner #3 packs a punch. It’s something like five times as potent as what federal researchers consider to be the norm, according to a 2010 Journal of Forensic Sciences paper. High Times marveled in a review: “Who knows what you’ll turn into after getting down with Bruce?”
As marijuana goes increasingly mainstream—and, crucially, develops into big (and legal) business—more super-potent novelty strains are likely to crop up. Bruce Banner #3 is the marijuana industry’s answer to The End of History, an ultra-strong Belgian-style ale that the Scottish beer-maker Brewdog made in a specialty batch—which was then served in bottles inside taxidermied squirrels—in 2010. Its alcohol by volume was 55 percent. That’s way, way stronger than most beers. “It’s the end of beer, no other beer we don’t think will be able to get that high,” James Watt, one of the founders of Brewdog, told me when I visited the Brewdog headquarters in Scotland in 2010.
Yet three years later, another Scottish brewery had whipped up a batch of barley wine called Snake Venom that boasted higher than 67 percent alcohol by volume.
This is human nature. Or maybe it’s just capitalism. One person makes a superlative product, which prompts the next person to best them. Given the opportunity to try something extreme—the biggest, the strongest, the best, the craziest—plenty of people will go for it. But most people don’t pick Snake Venom as their typical pint. And Bruce Banner #3 probably is not representative of the average joint.
For years, people have talked about increasing marijuana potency. The idea that pot is getting stronger—much stronger than the stuff that got passed around at Woodstock, for instance—is treated like conventional wisdom these days. Maybe it shouldn’t be.
“It’s fair to be skeptical,” said Michael Kahn, the president of Massachusetts Cannabis Research, a marijuana testing and research lab in New England. “Back then the predominant method for quantitation was gas chromatography, which is not quite appropriate for cannabinoid quantitation. This is because [it] heats up the test material before analysis, which also alters the chemical profile—including breaking down the THC molecule.”
Kahn’s lab uses a technique called liquid chromatography instead. Another potency tester, Denver-based CannLabs, uses a similar method. “Depending on what the sample is—flower, hash oil, hundreds of edibles ranging from ice cream to pasta sauce to seeds—you use different solvents to do the extraction,” said Gennifer Murray, the CEO of CannLabs. “You mix it with a special solvent, basically shake it around, centrifuge it, and then it goes onto the instrument. That’s the liquid chromatograph.”
The federal government has been testing marijuana potency for more than 40 years, and has long acknowledged the limitations to its methodologies. Along with some of the issues with gas chromatography—which it was still using at least as recently as 2008—the National Institute on Drug Abuse potency testing has always depended on what researchers have been able to get their hands on. Since 1972, tens of thousands of test samples for the Potency Monitoring Program have come from law enforcement seizures, which have varied dramatically in scope and type. A drop in THC concentration in the early 1980s, for instance, was attributed to the fact that most of the marijuana researchers analyzed came from weaker domestic crops.
In National Institute on Drug Abuse studies over the past several decades, the age of samples has varied from a few weeks old to a few years old—and researchers made no attempt to compensate for the loss of THC during prolonged storage, according to a 1984 paper. They also get different results when taking into account how the potency of a particularly large seizure could skew the overall sample. For example, measured one way, researchers found what looked like a continuous and significant increase in potency in the late 1970s. But normalizing those findings showed there was “an increase up to 1977 with slight decline in 1978 and a significant decline in 1979,” according to a 1984 paper in the Journal of Forensic Science.
More recently, researchers found a THC concentration that “gradually increase[d]” from 1993 to 2008, according to a 2010 paper in the Journal of Forensic Sciences. And despite testing limitations, researchers have always maintained potency is likely trending upward. But they’ve also always been upfront about the limitations to their findings: “The change in cannabis potency over the past 40 years has been the subject of much debate and controversy. The [Potency Monitoring] program has strived to answer this cannabis potency question, while realizing that the data collected in this and other programs have some scientific and statistical shortcomings.”
Ultimately, researchers have found a “large variation within categories and over time,” they wrote. That’s in part because sample sizes have fluctuated. (In the 1970s, researchers assessed anywhere from three to 18 seizures a year. In 2000, they analyzed more than 1,000 seizures.)
In other words, it’s difficult if not impossible to classify average potency in a way that can be tracked meaningfully over time. So while there’s almost certainly more super-strong pot available today—if only by the fact that it’s now legal to buy in multiple states—it doesn’t mean that all marijuana is ultra-potent today, which is how the narrative about potency is often framed. There’s also a point at which most strains can’t get much stronger. “Anyone getting a reading over 25, it’s really hard to do,” said Murray of CannLabs. “And then it doesn’t necessarily mean you’re going to quote-unquote get higher. There’s a lot of things that go into the plant—over 500 constituents of the plant that play into this.”
Federal researchers, too, have characterized marijuana strains with THC concentrations above around 15 percent as unusual. “The question over the increase in potency of cannabis is complex and has evoked many opinions,” researchers at the University of Mississippi wrote in a National Institute on Drug Abuse analysis of marijuana potency between 1993 and 2008. “It is however clear that cannabis has changed during the past four decades. It is now possible to mass produce plants with potencies inconceivable when concerted monitoring efforts started 40 years ago.”
Even without knowing reliably what potency was like in the 1960s and 1970s, it’s reasonable to guess it will increase, says Kahn, of Massachusetts Cannabis Research. “I think the mega-potent strains may soon represent the norm, if not already—the market selects for potency.” But with customers clamoring for the strong stuff, there’s also a question of whether manufacturers are labeling accurately. A Denver Post investigation last year found wide discrepancies between labeling and THC content—in many cases, products advertised a much higher percentage of THC than an edible product actually contained.
Either way, a shift toward high potency has arguably more to do with contemporary market forces than with a younger generation of marijuana enthusiasts. “The Baby Boomers have been growing for 40 years,” Murray said. “And now they can grow without being worried about the police.”
How incomplete government data encourages a pervasive pot myth