High THC strains have always been in demand, but especially so after the Cannabis Cup pitted US growers against each other, making it a genuine, bona fide competition with machines doing the measuring.
At first, the Cannabis Cup was a relatively small competition in Amsterdam that started in 1988. It’s been held there every November until 2015.
At that time, cannabis legalization started picking up steam in the United States, which pushed cannabis production to a whole new level.
After the 2014 event, Cannabis Cup became the High Times Cannabis Cup, and it was announced that in 2015 the event will be moved overseas to the United States.
Just like with everything else—when America gets involved, things start to get blown out of proportion.
Ever since, each consecutive event has brought higher and higher THC levels to the table.
What Is Considered a High THC Strain?
If you ever talked to a veteran cannabis user, you’ve inevitably heard the “in my time, weed was not this strong, and we still got high” story.
The premise is that the numbers cannabis growers were getting in the earlier days were mostly up to 10% THC.
However, this wasn’t always the case.
The numbers often came from the Police Departments, District Attorney’s offices, or similar authoritative agencies, and they showed the potency of the weed they confiscated.
The confiscated weed usually came from Mexico, was of low quality, and almost always tested below 10%. This low quality, cheap weed was called “brick weed” and it was one of the biggest problems during the war on drugs.
Cannabis in 2020 is much different, and that is in part due to legalization in the US.
Homegrown weed is more present, and products often leak from dispensaries to streets through the hands of their customers.
There is a bunch of different names for good weed today, so if someone says chronic, dro, sensimilla, dank, kush, skunk, haze, or “that good good”, you know he’s not looking to buy a bag of seedy brick-weed.
So, with that change, the expectation of cannabis consumers in the US started to increase.
Good weed was in demand.
The Rise of Elite Weed
Over the course of the early 2010s, we saw the rise of an “elitist” smoking society, if I may say so.
Cannabis strains that tested for over 20% THC were being grown left and right.
Nowadays, when someone says that they are looking for a high-THC strain, it means they’re looking for a strain with over 18% THC.
Once again, keep in mind that the test results displayed on the packaging of the products displayed in dispensaries can be skewed and misleading.
In order to come up with a list of the highest THC strains, I relied on Washington State’s I-502 data for most of the numbers quoted in this article.
Since we are looking for only the highest THC strains in this article, we won’t take into account some other factors, such as CBD levels and genetics. However, it’s good to know that the presence of terpenes can greatly contribute to a user’s experience of the strain’s potency.
High THC Sativa Strains
Sativa strains are generally known to be uplifting, high in THC, and they are very good for growing outside.
They tend to be taller than Indica plants, with long branches and thin leaves. They are used to all types of weather and they can be exposed to the elements without suffering.
Pure Sativa strains (landraces) take longer to flower. They can grow a lot and become quite hard to maintain and harvest at the right time because of their size.
It’s important to note that we will also include a couple of Sativa-dominant hybrids in this list as well, as hybrids usually tend to be more potent than pure strains.
This strain is a pure Sativa which was made by crossing Thai and Mexican/Colombian genetics.
Destroyer has about 20% THC, which is pretty high for a pure Sativa. It was first grown by CannaBiogen.
Smoking on some Destroyer will leave you with a somewhat cerebral effect, but mostly uplifted and energetic.
One of the reasons why we included this strain in the list, aside from its high THC content, is because it grows faster than most Thai-crosses.
It is mold-resistant and usually flowers in about 8 to 12 weeks. It gives off a sweet taste and a very strong smell of lavender.
This strain got its name after the highest mountain in Africa. The name is very appropriate as this strain also has one of the highest THC contents of all Sativa strains.
It is a landrace that was first grown on the mountain slopes of Tanzania. Just like with most Sativas, this strain’s effects are primarily energetic and uplifting.
It gives off a taste of citrus fruit and spices and has a very pleasant aroma.
Kilimanjaro is one of the highest THC strains in Canada, as it is popular among users in Calgary, Toronto, and several other bigger cities across the Big North.
This strain was largely grown in Europe before coming to Canada and the US, and can have up to 20% THC.
You can find Kilimanjaro on sale at the World of Seeds and Delicious Seeds.
Thai is one of those strains that are the dream of long-time growers, as it is one of the rare strains that grow huge and still have up to 22% THC.
It was brought over to the US by returning soldiers from the Vietnam War in the 70s and 80s.
Thai usually has a strong, distinct fruity, citrus aroma. The flavor is somewhat different though, as users say it tastes earthy and somewhat woody. It’s a bitter taste all-together, but a great high.
This strain will definitely keep you uplifted and focused; just don’t smoke too much of it as the high is intense.
Thai is popular across the United States, although it is easily found only in Washington state and Portland. It also has a large presence throughout Canada.
Since this strain is so popular, seeds can be found on sale online on several popular websites.
Ghost Train Haze
Ghost Train Haze may be the most popular Sativa-dominant hybrid out there. It was named by High Times as one of the “Strongest Strains on Earth”.
This strain is a mix of Ghost OG and Neville’s Wreck. Its genetics are 70% Sativa and 30% Indica, although we still listed it here because of its effects.
Ghost Train Haze has the prototypical Sativa profile, as it will give you a high which is energetic, uplifting and uplifting. If you are naturally creative, this strain will awake that in you!
It once tested for 28% THC, which is probably the highest result a Sativa tested for, although this isn’t confirmed data.
Only when you taste this strain will you see the India presence in it, as it gives off a bit of a kushy flavor, with just a hint of fruit.
The seeds are sold online by the breeder Rare Dankness, but you can also buy it in many dispensaries across the US.
This is one of my personal favorite strains. It honestly reminds me of college and the times I smoked the strongest strain in my life.
Trainwreck genetics go far back, as it was first made by crossing Mexican, Thai and Afghani, which are all known to be strong landraces.
While Mexican and Thai are pure Sativas, Afghani is a pure Indica. This mix is what gives Trainwreck its potency, but also the reason why it kept its Sativa-like effects.
Since it won a couple awards in the past, Trainwreck became hugely popular in all places across the US and Canada. It is also loved among growers because it is easy to grow, and has a very high yield.
Trainwreck seeds can be bought online in just about any seed bank, while the flower can be often found in dispensaries in Oregon and California.
Honorary Mention: Sour Diesel
Sour Diesel has been a fan favorite for years, however, it somewhat fell out of favor with the introduction of newer strains, especially easy-to-grow hybrids with similar effect.
Sour Diesel boasts an average testing of 19% THC, and is known for its thick colas that are notoriously hard to grow.
High THC Indica strains
Indica strains originated in Central Asia and they tend to be somewhat different from Sativa strains in both effects and appearance.
They tend to be much smaller and bushier than their counterparts, while their leaves are wider and thicker. They also smell a lot different than the Sativa strains which are almost always fruity in aroma and taste.
These strains historically grew in mountainous climates, which is why they are shorter and they can take cold weather rather well. They also have a much more pungent smell than Sativa’s.
It goes without saying that India strains are some of the highest THC strains in the world.
Numerous purebreds and Indica-heavy strains tested for over 25% THC, which is unheard of in the world of high THC Sativa strains.
This strain was probably one of the “most-in-demand” strains of early 2010s, as it won several awards at that time.
Six of the largest testing labs in Washington State tested several strains for potency: Kosher Kush was one of the highest-rated, and it consistently came in at over 21% THC.
Some results during the Cannabis Cup testing in 2010 and 2011 when it won Best Indica and Best Strain, respectively, came at a whopping 29% THC.
Kosher Kush is hugely popular on the West Coast.
It has a fair yield, flowers quickly and hits like a truck.
Another strain from the Kush family which is responsible for people craving record-setting levels of THC.
Now, Purple Kush is by no means one of the tastiest or the best smelling strains of all. It has a weird, almost peppery taste that doesn’t go away unless you cure your buds extensively.
So, you may wonder why it is that popular, but when you learn that Purple Kush once tested for an astonishing 27% THC contents, it becomes clearer.
It was first bred in Oakland, for the exact purposes of entering and winning a competition.
Seeing how its crossed from Hindu Kush and Purple Afghani, you can expect that couch-locking high which will leave you feeling blissful.
Are you starting to see a trend here?
It may seem I’m a little biased here. I mean, I do like kushes but that’s not the point, they really are some of the highest THC strains.
Afghan Kush is an Indica that has been popular for a while now. It is the product of the Hindu Kush mountain range.
This strain has been tested left and right, with various results from 16% to over 25% THC content, so we can’t really pinpoint the number.
It is very easy to grow both indoors and outside, as it is resistant to mold and mildew, and it has huge yields compared to its size.
This strain is a close relative of the Afghan Kush, as they both come from the same mountain range.
It is entirely possible that Hindu and Afghan Kush crossed paths at several points, which is why they are so much alike.
The Hindu Kush has really good genetics because it had to get used to growing high up in the mountains. This is why as a strain it is known for its many trichomes and resistance to the elements.
Recent testing has shown that Hindu Kush can go as high as 23% THC contents, although traditionally it tested anywhere between 15 and 20 percent, so the newest results might be skewed.
Seeing how most Indica strains are at least part-kush, it felt appropriate to round out the Indica list with another kush.
This strain isn’t a pure Indica like the other ones on this list, but an Indica-dominant cross with all the traits of Indicas.
Critical Kush is a new strain that came as a result of crossing OG Kush with Critical Mass, both of which are known to be heavy hitters.
Tests keep coming positive for THC contents of up to 20-25%, which is to be expected from such a potent strain. It gives a strong, long-lasting calming buzz which will have you relaxed for hours.
Aside from being potent, Critical Kush is also somewhat easy to grow and it has massive yields which come from very thick buds.
Honorary Mention: Grandaddy Purple
Grandaddy Purple is one of the most popular pure-Indica strains. It has a somewhat grape and berry flavor, which is where it gets the second part of its name.
If grown and dried properly, this strain can also have beautiful purple strands and hairs. It is very easy to grow and best grows in the ground indoors.
American Grandaddy Purple tested for over 20% THC contents several times, and several times just below, so the average came at a decent 17.5%.
High THC Hybrid Strains
Hybrid strains are crosses that aren’t too dominant in any of the two standard types — Indica and Sativa.
They are really the best of both worlds, as breeders try as hard as they can to make these new strains the combination of the best genetics their parents have to offer.
No matter how much you love the cerebral-high THC of Indica strains or the uplifting and energetic high that Sativas provide, you will definitely fall in love with the hybrids once you try them.
Original Glue or Gorilla Glue #4
We’ve already talked a lot about this award-winning, mind-numbing strain that has been taking over the world of weed for the last few years.
It was made several years ago for the specific purpose of winning the Cannabis Cup, which it did.
Gorilla Glue #4, or Original Glue as it is now known due to some legal dispute regarding the name of the strain, has been tested several times and each time it came at over 20% THC contents.
If you want to know more about this strain, please read our full review of Gorilla Glue #4.
This strain became hugely popular in California some 20+ years ago, right around that time when Dr. Dre dropped “The Chronic” album.
It is an Indica-dominant strain that regularly tests between 20% and 25% THC content.
OG Kush has a range of tastes, you may feel the earthy and piney aromas quickly spread around the house and your backyard.
There are many different phenotypes of OG Kush, which means that its genetics are incredibly strong and in demand for growing.
Girl Scout Cookies
This is another strain that became almost exclusively grown in California. It is a mix of OG Kush and Durban Poison, thus it has strong genetics and high THC content.
Just like with OG kush, there are several different types of the GSC strain which register different levels of THC.
However, in Washington State’s test database, Girl Scout Cookies came at a decent 19% THC content. Other results showed a bigger presence of THC, even up to 25-28%.
It has the looks of an Indica strain, but its effects are more similar to a Sativa as it leaves users happy, uplifted and energetic — just like girl scouts selling cookies door to door.
Wappa is a 60% Indica-dominant hybrid, which is perfectly balanced in its effects.
Its aroma is very fruity and sweet, and the smell is very potent and citrusy.
In the past, Wappa tested for THC levels ranging from 18% to 19% on average, until the American growers got their hands on it.
According to Washington State’s I-502 data, Wappa came in second in THC levels, only behind Ghost OG.
Wappa is relatively easy to find across the US and Canada. It has a very big presence in Europe as well, even in countries that haven’t legalized cannabis because it flowers quickly and has impressive yields.
This strain got its name after one of the most iconic Marvel characters ever—The Amazing Hulk, or rather the genius scientist who became Hulk.
This strain won’t turn your skin green and make you rage, but it’s safe to say that Bruce Banner himself would be impressed with it if he were a real person.
Washington State’s results show that Bruce Banner constantly tested for over 24% THC content, making it one of the top 3 strains with high THC, only behind Ghost OG and Wappa.
Its genetics come from OG Kush and Strawberry Diesel, making it a perfect mix of Sativa and Indica genes. Bruce Banner strain has a very fruity aroma and an uplifting, energetic high.
Honorary Mention: Ghost OG
So, we mentioned that according to Washington State’s data, Ghost OG came in first with the highest amount of THC content. It consistently came in at over 28%, which is unheard of.
Why didn’t we include it in our list? Well, to be frank, Ghost OG is nothing more than a spinoff of OG Kush.
“How come?” you might say, and the answer is: It’s complicated. Nobody knows the real genetics of this strain, but it mostly resembles OG Kush as that’s what it has been crossed with.
The strain appeared some time ago, when a forum member by the name of OrgnKid passed the cut to a forum member named Ghost, giving the strain its name.
Ghost OG isn’t that hard to find anymore, because now it’s a fan-favorite. It is present all over the West Coast, Oregon in particular.
Just like OG Kush, it has a heavy sedative effect, which will leave you sitting like a stone on weeds. The taste is great, the smell is even better, and you can bet that it is easy to grow.