With the creativity and ingenuity of the country’s cannabis brewers, new and exciting strains debut every year. It’s easy to get lost in the hundreds, and sometimes thousands, of available strains. Though the potency isn’t the only indicator of a strain’s quality, high THC content is a much sought-after quality among the best weed strains of 2021.
What makes a cannabis strain high-THC? Is there a threshold? Today’s top strains boast THC levels approaching 30%, and the standard for high THC content is 20% these days. Anything over 25% THC is considered extremely potent. The effects of tetrahydrocannabinol are different for everyone, and at high concentrations, those effects are much more pronounced.
In this guide, we’ll clear up some of the confusion by going over some basic facts and recommending some of the best weed strains for 2021.
THC and Its Effects
The consumption of the best types of weed, which are high in THC, comes with many beneficial effects. However, there can be some adverse effects as well. That’s why we suggest that beginners start with strains containing 15% THC or less and gradually work their way up.
The most well-known effect of tetrahydrocannabinol is euphoria. That’s the high we all associate with smoking the best weed strains of 2021. Cannabis is a bliss-inducing mood lifter that, unlike other drugs, lets the user stay in control. It provides support and relaxation during tense times, but it may also lead to altered perceptions of time in some users.
One of tetrahydrocannabinol’s most noteworthy effects is its ability to promote relaxation—particularly at high doses—and its ability to promote natural sleep. Conversely, THC may also lead to short-term memory loss, which is part of the pothead stereotype. Thankfully, though, the effects only last as long as you’re high.
2021’s Most Popular Top 10 Cannabis Strains for 2021
Now that you’ve learned a bit about the effects of THC, we’ll go over the best weed strains of 2021. Experienced users will find themselves embarking on new adventures, while new smokers should proceed with caution when trying the best types of weed.
1. Bruce Banner
Of all the options on our list of the best weed strains of 2021, this is likely one of the most powerful. Bruce Banner got its name from a comic book superhero called the Hulk, or more accurately, the Hulk’s human alter ego. With one taste of this powerful strain, it is easy to see how it earned its name.
Effects
Bruce Banner is a Sativa-dominant cannabis strain that packs a powerful punch. The effects come on quickly and give the user a mellow euphoria that is well-suited to creative work and relaxation. Bruce Banner is known for its pain killing effects and is popular among users for treating the symptoms of anxiety and ADHD.
THC Content
Bruce Banner has dense buds with a high THC content. Depending on the strain and growing conditions, Bruce Banner buds can reach a THC content of up to 30%. Most frequently reported are THC contents of 20-26%, which is still very high.
CBD Content
The CBD content of this strain is fairly low, ranging between 0% and 1%. Users looking for a high CBD content should try a different strain.
Genetics
Bruce Banner is a cross between Strawberry Diesel and OG Cush. It comes in three variants, with the third being the most highly sought-after strain. It is a strong strain that won first place at the Denver Cannabis Cup and was regarded as one of the most potent strains available in 2009.
Growing Guide
Bruce Banner plants reach up to six feet tall and take 65-70 days to reach harvest. They are moderately difficult to grow compared to some other strains and are fungus and pest resistant. They have bright green leaves with rich green buds that are completely covered in crystals and boast bright red and orange hairs.
If growing indoors, the plant does well with topping and promoting a widespread over upward growth. The limbs are strong and won’t break easily, so the plant responds well to low and high stress training.
2. Trainwreck
Trainwreck is a highly sought-after strain of cannabis for its high Sativa content but strong Indica characteristics. It gained its name through California lore that says the two brothers who developed the strain had to pull their crop early to avoid detection due to a train wreck nearby.
Effects
Trainwreck’s Sativa content gives users a cerebral high that is incredibly euphoric. The small Indica content packs a powerful punch, giving the user a lazy, relaxed feeling excellent for chronic pain and joint stiffness.
THC Content
Trainwreck has a moderately high THC content that can range between 15% and 20%. However, its effects mimic that of more potent strains.
CBD Content
Trainwreck has a low CBD content of between 0% and 1%. It is not an ideal strain for users that are looking for a mild psychoactive effect.
Genetics
Developed in the 70s, Trainwreck is a cross between Thai, Mexican, and Afghani strains. Because it has been around for several decades, the genetics of this strain are stable.
Growing Guide
Trainwreck is a great strain for both indoor and outdoor growing. Because it is a Sativa dominant strain, these plants grow very tall, up to 10 feet tall. Under the right conditions, a single plant can yield up to 700 grams.
Trainwreck tolerates cooler greenhouse temperatures. It spends between 8 and 9 weeks in the flowering period. If grown outdoors, it is ready to harvest in early October.
3. White Widow
White Widow is a legendary strain that has won several awards, including the High Times Cannabis Cup in 1995. It is a sticky resin-heavy strain bred for its incredibly high trichrome count and is used heavily by hash makers.
Effects
White Widow has all the benefits of an Indica-dominant strain, including a comforting buzz that’s perfect for treating chronic pain. Its Sativa component offers users a cerebral high that keeps them able to focus and converse, even in the height of its effects.
THC Content
The average THC content for White Widow is around 20%, making it a superb choice for users who want a comfortable high that doesn’t leave them unable to function. Under the best conditions, White Widow can reach a THC content of 25%.
CBD Content
The CBD range for White Widow is fairly low, between 0% and 1%.
Genetics
White Widow is a genetic blend of Brazilian Landrace Sativa and South Indian Indica. It was first developed in the 90s by a famous Dutch seed company called Green House Seeds.
Growing Guide
Though White Widow contains more Sativa genetics than Indica genetics, it looks more like a bushy Indica plant during its vegetative stage. It spends between 8 and 9 weeks in the flowering stage, which is punctuated by sugar-dipped buds that give the strain its name. When grown indoors, this plant can yield up to 500 grams per plant, and when grown outdoors, it can yield up to 700 grams per plant.
4. Chemdawg #4
Chemdawg #4 has been a popular strain with many well-renowned variations for several years. It is one of the most popular strains used for medicinal purposes.
Effects
Chemdawg #4’s effects are lasting, giving users an extended period of relaxation, euphoria, and contentment. Users report both feelings of couch lock and a boost in creativity from its heavy hitting effects. It stimulates appetite significantly, making it a top choice for those who seek to relieve nausea associated with chemotherapy or who suffer from anorexia.
THC Content
Chemdog #4 boasts a high THC content, reaching up to 28% under the right conditions. This makes it a heavy-hitting strain perfect for relaxation and sedation.
CBD Content
The CBD content of Chemdog #4 is 0%. Cannabis users who need a higher CBD content for medicinal purposes should choose another strain.
Genetics
Chemdawg #4 is developed from a cross between Nepalese Landrace and Thai Landrace. Chemdawg is used to crossbreed with other strains for its THC content and potentially medicinal properties. The origins of Chemdawg is a mystery, but it has produced such wildly popular strains as Sour Diesel and OG Kush, making it a favorite for many.
Growing Guide
Chemdawg #4 can be grown indoors or outdoors, but it is one of the more challenging strains to grow. This strain requires consistent trimming and pruning to achieve high yields. It spends an average of 9 to 10 weeks in the flowering stage and has a moderate to heavy yield, reaching as high as 850 grams when grown outdoors in perfect conditions.
It has a low resistance to mildew but a high resistance to pests and mold. Unlike many other strains, Chemdawg #4 likes a humid climate and can grow up to 7 feet tall.
5. San Fernando Valley OG Kush
San Fernando Valley OG Kush, or SFV OG, is an Indica-dominant strain developed by Cali Connection. It is a potent strain that is favored by medicinal and long-time cannabis users.
Effects
SFV OG gives users a relaxed, euphoric feeling that leaves them happy, tired, and stress-free. It hits the user fast and leaves them couch bound, making it an excellent choice for those who suffer from insomnia or anxiety.
THC Content
SFV OG Kush is a heavy-hitter, with a THC range from 22% to 25% under ideal conditions. Though it isn’t the highest level on the list, it packs a punch that is not recommended for those new to cannabis.
CBD Content
The CBD content of SVF OG is negligible, at not much over 1%.
Genetics
San Fernando Valley OG Kush is a strain developed from the Sativa-dominant San Fernando Valley and Afghani. The blending of the two strains makes SFV OG an Indica-dominant plant that packs a heady, euphoria along with a sedative effect.
Growing Guide
SFV OG plants can get fairly tall but take a lot of its plant traits from the bushy Indica genetics of Afghani. It spends between 8 and 10 weeks in the flowering stage and can yield up to 500 grams per plant. The buds are dense and bright, algae-green colored with a heavy covering of frosty-white trichomes.
6. Grandaddy Purple
Grandaddy Purple is one of the most famous strains out there. Created in 2003 by Ken Estes in California’s Bay area, it features intense purple buds with bright orange hairs that are dense enough to drag down branches as they mature.
Effects
Users report that Grandaddy Purple packs an immediate punch that fades into a calming body high. It is ideal for pain management and has been said to be effective in relieving anxiety, insomnia, and depression.
THC Content
Grandaddy Purple is an Indica-dominant strain that has a THC content between 16% and 24%. Because it is mostly Indica, the sedative, euphoric effects are hard-hitting and recommended for more experienced users.
CBD Content
The CBD content of Granddaddy Purple is low. However, the calming and pain-relieving effects of the strain make it popular for medicinal purposes.
Genetics
Granddaddy Purple is a famous cross between Purple Urkle and Big Bud. It is a staple among California cannabis enthusiasts and bears remarkable similarities to the strain Grape Ape.
Growing Guide
Granddaddy purple can be a finicky plant to work with and is recommended for more experienced growers. Its dense buds are highly susceptible to mold. For the best results, growers must keep the ambient temperature around the plant between 70 and 80 degrees Fahrenheit.
The plant has massive yields and takes between 7 and 9 weeks to mature. It is better suited for indoor growing, and its short and stocky nature makes it an ideal candidate for those with an indoor growing setup.
7. Green Crack
Green Crack was originally called Green Cush, but was renamed Green Crack by world-famous cannabis enthusiast and hip-hop artist Snoop Dog. Despite a more short and stout Indica appearance, Green Crack produces a stimulating and euphoric Sativa experience.
Effects
Green Crack was given its name for the boost of energy the user receives after consuming it. It offers a buzzy high that is boasted as an excellent strain for consumption right after waking up. It helps users enjoy mundane tasks and gives them a hearty boost in creativity and focus.
THC Content
Green Crack has a higher THC content that other strains, with a maximum of 25% under the best conditions. Though it is comparable to other strains on the list, few strains match the energetic high that comes with Green Crack.
CBD Content
Green Crack has a moderate amount of CBD, ranging between 3.5% and 7%. This higher CBD content and Green Crack’s energetic effects make it a popular strain among those who are treating chronic conditions with CBDs.
Genetics
Green Crack was originally bred in Athens Georgia in the 70s. Many users don’t agree on the origin of Green Crack, but it is mostly considered a cross between Afghani Sativa and Skunk.
Growing Guide
Green Crack plants can get between 5 feet and 7 feet tall, producing as much as 1-3 oz per foot of plant. The flowering time for Green Crack is between 7 and 9 weeks and it produces tight, dense buds that are loaded with bright orange hairs. The entire plant is covered in crystals, with even the stems and fan leaves having a smattering of crystals throughout.
8. Zkittlez
Zkittlez is a tasty strain that has won several “Best in Class” awards since its introduction. This Indica-dominant strain is potent, but its biggest claim to fame is the number of colors that are present on the plant.
Effects
Zkittlez offers a multifaceted high that reflects both the Sativa and Indica strains in its lineage. The high comes on quickly and is predominantly a heady, euphoric feeling. However, the effects are fairly subtle, making it a perfect strain for those who are just getting used to smoking cannabis. Sensory distortions are frequently reported by its users.
THC Content
Zkittlez has a THC range between 19% and 23%. Though it has a heavy THC content compared to some other strains, its low-key onset makes it an easy strain for beginners and more experienced users alike.
CBD Content
Zkittlez has a low CBD content between 0% and 1%. It is not recommended for those seeking a high CBD strain, but it is still a great introductory strain for those who need to get used to the effects of smoking cannabis.
Genetics
Zkittlez is an Indica-dominant blend of Grape Ape, Grapefruit, and a mystery strain. It has gained popularity among medicinal cannabis users, as it helps relieve chronic pain and increases appetite.
Growing Guide
Zkittlez is a relatively easy plant to grow and can reach a height of about 6 feet. This plant does not have as heavy of a yield as other strains but can deliver 132 grams per three-foot area. The flowers are light green with a coating of frosty trichomes and bright yellow hairs.
9. Gorilla Glue #4
Gorilla Glue #4, or GG #4, comes from a long line of Gorilla cannabis strains and has won multiple awards. Created by GG strains, it is most well-known for its high THC content and earned its name because of the amount of resin that builds up on a person’s scissors when they trim the buds.
Effects
GG #4 is potent, leaving users with a heavy feeling of relaxation and calm. It is a sedating full-body high, despite being a Sativa-dominant strain. It provides uplifting effects that promote euphoria and sleep. It is not a great strain for first thing in the morning, but is excellent at treating insomnia, depression, and anxiety.
THC Content
GG #4’s claim to fame is its high THC content. It has an average THC content of 26% to 28%, but some growers can get up to 32% THC.
CBD Content
GG #4 has a low CBD content. It ranges between 0% and 1%, but typically reaching only 0.5% at most.
Genetics
GG #4 was bred from Chem Sis, Sour Dubb, and Chocolate Diesel. The result is an almost perfectly even ratio of Sativa and Indica.
Growing Guide
GG #4 is highly resistant to disease and prefers dry, warm climates. It is a fast growing and tall plant that requires regular trimming. Growers have been able to get up to 21oz per plant when grown outdoors.
The buds are chunky and covered in resin, often being compared to the color of a silverback gorilla. Some growers have described this strain as a fistful of trichomes with a few buds attached.
10. Fire OG
Fire OG is an Indica-dominant strain with a powerful lemon aroma. It is among the most potent OG strains and is perfect for those who have a high tolerance for THC.
Effects
Fire OG is a relaxing strain, perfect for those who have trouble sleeping. It causes an almost instantaneous cerebral high with waves of euphoria that support creativity. It helps reduce anxiety and is used widely in the treatment of chronic pain and depression.
THC Content
Fire OG has a THC content of around 20%. While it is not the highest content on the list, its unique genetics help give it an extra punch that is potent, even for daily cannabis users.
CBD Content
The CBD content of this strain is low. Typically, the plant never reaches a CBD content higher than 1%.
Genetics
Fire OG comes from a long line of OG strains. This strain is a gross between San Fernando Valley OG Kush and OG Kush. It is used frequently for medicinal purposes including the treatment of insomnia, anxiety, migraines, joint pain, and nausea reduction.
Growing Guide
Fire OG is not a great plant for beginners, as it is fairly sensitive. It is susceptible to mold if there is too much rain and requires a lot of pruning. However, if done correctly, this plant has massive yields.
Hopefully this guide has been helpful for you and perhaps even introduced another strain or two that you had never considered growing before. Whether you choose one of the above or any other i49 seed, we wish you the best of luck in growing a juicy crop of beautiful buds. Read through our FAQ page and dozens of other grow guide article topics to be the most educated and prepared weed seed grower that you can be!