Medically Reviewed by
Jason Crawford

Article Last Updated on December 20, 2022

How Does the Potency of Modern Marijuana Compare to Marijuana From the 1970s?

Regardless of whether you’re a medical cannabis user or you use cannabis as a recreational drug, you’ve probably wondered how modern marijuana differs from the marijuana that growers cultivated earlier in the 20th century. It’s a fact that the potency of cannabis is different today compared to the 1970s when weed became quite popular around the world. 

According to a study done in 2016 by the National Center for Natural Products Research at the University of Mississippi, cannabis strains today are much more potent compared to cannabis strains 20 years ago. Today, medical marijuana users as well as recreational users can choose from a wide variety of high potency strains with different cannabinoid and terpene concentrations.

Let’s take a look at how much cannabis potency has increased today compared to the 1970s. We’ll also go over how different cannabis strains were back then from the ones we have on the market today.

What Did Weed Potency Depend on Back in the 1970s?

Weed potency in the 70’s depended on a few factors. 

How It Was Imported

Since weed was illegal back in the ’70s, it needed to be sold discreetly on the black market, which reduced its potency on account of how long it was kept. Until the 2000s, weed was packed, transported, and sold in the form of brick weed, which was a term coined to represent compacted marijuana. As a result of marijuana being illegal, sometimes the stash was kept for longer periods of time resulting in the conversion of THC to CBN, which reduced the potency of weed. Brick weed was imported from Colombia, Jamaica, Mexico, and Thailand, and was then sold on the US and European markets. 

How It Was Kept and Transported

Another thing that affects the THC potency in weed is light and air. As time passes, and if the weed is exposed to direct sunlight, high temperatures, and kept in a container that isn’t airtight, THC slowly degrades to CBN (Cannabinol). CBN has sedative effects which are the opposite of the psychoactive effects THC has on users. Since weed was illegal in the 1970s, dealers often hid it in various containers for longer periods of time, which may be one of the reasons why marijuana samples were less potent 50 years ago. Therefore, to keep weed in peak condition, it needs to be kept in a cool, dark place, away from direct sunlight. 

How It Was Grown

The 1980s and 1990s made way for new methods of cannabis cultivation – the hydroponic systems. This method enabled growers to create stronger and more potent products as a result of growing weed in solutions that are richer in nutrients. Moreover, this was the period during which growers started experimenting with hybrid strains and combining Sativa and Indica strains. Consequently, that led to the cultivation of weed with higher levels of THC.

How Potent Was Marijuana Back in the 1970s?

The levels of THC (tetrahydrocannabinol) have increased a great deal since the 1970s. According to an article from 2017, published in Dialogues in Clinical Neuroscience, the THC concentration in cannabis 50 years ago was less than 3%. On the other hand, the current THC levels of some weed strains are even more than 30%.

However, the tests on THC content from the 1970s may not be 100% correct, as the method used to measure THC levels was gas chromatography. This method involves heating the weed up before the analysis. The increased heat of the technique can cause THC molecules to break down, resulting in a potentially inaccurate reading. In order to get more accurate readings today, scientists use liquid chromatography.

The ’70s were a turning point for marijuana consumption, especially in the United States. With the passing of the Controlled Substances Act of 1970, marijuana became listed as a Schedule I drug. That made it illegal under federal law, which led to the increase of marijuana on the black market. Most of the weed was brought from Columbia in the form of brick weed.

Cannabis in the 1980s and 1990s

After the Controlled Substances Act, marijuana couldn’t be bought legally, and patients that needed marijuana as a treatment option had to buy it on the black market.

During the 1980s and the 1990s, the average potency of weed increased a great deal. In a 1988 study done at UCLA, the average potency of marijuana samples increased about 10 times. According to Dr. Richard Hawks at the National Institute on Drug Abuse, THC levels in weed increased from 0.5% in 1974 to 3.5% in 1985, and the potency of sinsemilla (seedless marijuana) increased from 6.5% to 12%.

According to the same 2016 study from the Mississippi University mentioned above, the average potency of THC in weed during the 1990s was 4%. However, as states started legalizing cannabis for medicinal uses and growing weed with the hydroponic method became more popular in the late 1990s, weed started to become more potent.

2000s and the Era of Modern Marijuana

The increase of potency of sinsemilla was noted in the early 2000’s, and by 2014, the average THC content in weed was 12%. Moreover, the ratio between THC (tetrahydrocannabinol) and CBD (cannabidiol) also changed. Within 20 years, the ratio of THC to CBD went from 14:1 to 80:1, which also contributed to the increase of potency of marijuana. With the growing, widespread legalization of cannabis and cannabis products for medicinal and recreational use across the United States, THC content increased even more.

Is Modern Marijuana Stronger?

With newer methods of cannabis cultivation comes more potent and high-quality cannabis. What was once unheard of is now a reality: the average levels of THC found in weed are higher than ever. And, as the marijuana market is expanding, new strains with even higher THC levels appear on the market, like the strain Godfather OG which was listed as the most potent strain ever in 2017 by the High Times magazine.

According to a study done by The University of North Carolina in 2020, today’s marijuana samples are more potent than ever, with the majority of medicinal or recreational cannabis products having THC levels higher than 15%.

Due to the cultivation of hybrid strains, as well as new weed products that appear on the market, growers focus on cultivating the most potent strains in the world. Today, you can buy different cannabis products like cannabutter, cannabis oil, weed brownies, moon rocks, hash oil, kief, resin, dabs, or the plain cannabis flower. These products have higher THC levels than the ones hippies used back in the 1970s, and you can buy them from your local dispensary.

Final Thoughts on Cannabis Today

As the legalization of the cannabis plant spreads throughout ever-growing numbers of US states, so does cannabis use, especially recently due to the Covid-19 pandemic. The cannabis industry has become quite lucrative, and a market analysis shows that it’s expected to exceed $20 billion by 2024 in the United States alone.

With more people wanting to try out cannabis both recreationally and medicinally, it’s very likely that we should be expecting more and more high THC strains in the future. Only time will tell how the cannabis industry will evolve, and what new products it will bring to prospective users that are looking for a toke to start or end their day with.

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


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