The best high-THC strains indoor growers need this year

Explore ILGM’s list of heavy-hitting strains. 

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Seasoned grower or growing novice, we can all agree that one of the best parts about growing weed indoors is having the ability to control our crop’s environment. When we properly regulate factors like light, climate, and air circulation, it’s almost a guarantee that our harvests will yield some pretty amazing weed. But what makes the difference between pretty amazing weed and top-tier weed? It all starts with the right strain. 

Large-scale cannabis grower and breeder Robert Bergman learned the importance of choosing the right strain when he started growing cannabis at home 25 years ago. What started as just five little plants grew into I Love Growing Marijuana (ILGM), a business that helps cannabis connoisseurs become successful cannabis growers. With more than 200 grow guides on every stage of cannabis production, community-driven grow journals, and in-depth profiles on the best cannabis strains, ILGM is an amazing resource for all levels of growers. 

Among some of the best strains for indoor growers are those with high levels of THC. Cultivating high-THC strains is perfect for those seeking high-potency rewards, and the unique conditions of indoor growing allow these hard-hitting strains to be even further optimized. Below are eight of the best high-THC strains for indoor growers this year, so take a peek and see what’s right for you. 

When you’re ready to get growing, visit the internationally available ILGM shop for seeds and everything else you’ll need.

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Gorilla Glue

50/50 hybrid

Known for having super high THC levels up to 26%, Gorilla Glue is a popular hybrid strain that delivers deeply euphoric and relaxed vibes. Born from parent strains Chem’s Sister, Sour Dubb, and Chocolate Diesel, Gorilla Glue has a notably rich and earthy aroma, and its flavor profile makes it a popular edibles strain. With a hearty constitution and high resistance to disease, this strain is fairly easy to grow—making it a great option for beginners. 

Available from ILGM both feminized and autoflower.

Zkittlez

70/30 indica

Just as sweet and colorful as its name suggests, Zkittlez is an indica-dominant strain that produces a complex, fruity aroma and beautiful buds in green, purple, and orange. A mix of Grape Ape and Grapefruit, this strain boasts THC levels up to 23% and relaxed and uplifted effects that result in a perfectly balanced, mellow high. Generally compact and bushy and fairly resistant to mold and mildew, Zkittlez is a great strain for indoor growing beginners. More advanced growers can easily train their Zkittlez plant to optimize its yield. 

Available from ILGM both feminized and autoflower. 

GSC Extreme

80/20 indica

GSC Extreme is a super-powered, indica-dominant variation on standard GSC. A hybrid of parent strains Durban Poison and OG Kush, this strain features high-THC levels up to 21% and promotes feelings of relaxation, happiness, and creativity. The plant’s aroma recalls notes of chocolate, mint, and a touch of spice, while its flavor is both sweet and complex. This strain is relatively easy to grow, but indoor growers should keep space in mind, as these plants love to grow both up and out. 

Available from ILGM both feminized and autoflower. 

Bruce Banner 

60/40 sativa

Bruce Banner is known to pack a punch. With extreme THC levels up to 25% and an intense rush of euphoria and energetic joy, this green monster produces a happy “Hulk effect.” A blend of OG Kush and Strawberry Diesel, Bruce Banner’s smell and flavor profile is undeniable, with a unique combination of fruit and diesel. Bruce Banner is also a hearty plant that produces highly potent, huge yields. 

Available from ILGM both feminized and autoflower.

Gold Leaf

60/40 indica

Cultivated by ILGM’s founder Robert Bergman, Gold Leaf is an indica-forward strain that delivers immediate feelings of happiness, euphoria, and creativity. This strain boasts THC levels up to 21% and has a uniquely pungent, earthy aroma and flavor. Bergman designed Golf Leaf for all levels of growers, ensuring high yields and easy cultivation both indoors and outdoors. When growing indoors, make sure to manage the plant with proper cropping and pruning to ensure a steady growth rate and optimal results.  

Available from ILGM both feminized and autoflower.

Blue Dream

80/20 sativa

Born from Blueberry and Super Silver Haze, Blue Dream is one of the most popular strains on the market, best known for its smooth, relaxing daytime high. The sativa-forward strain from California features THC levels up to 21% and a distinct blueberry scent and flavor profile with touches of vanilla and spice. The Blue Dream plant is on the taller side and its sweet scent can attract parasites, so it’s ideal for indoor growing.

Available from ILGM both feminized and autoflower.

Banana Kush

60/40 indica

Born in the Golden State, this bright green, indica-dominant strain is known for its chill, happy vibes. With incredibly high THC levels up to 27% and a stimulating buzz, Banana Kush is a favorite among creatives and social butterflies alike. Sweet as a banana, Banana Kush promotes feelings of happiness, euphoria, and relaxation. Growing Banana Kush is best for more experienced growers, as it requires constant air flow, pruning, and (ideally) an indoor hydroponic setup. 

Available from ILGM both feminized and autoflower.

Autoflower Super Mix

Gorilla Glue Auto, Bruce Banner Auto, GSC Extreme Auto

Looking for the all-star roundup? The Autoflower Super Mix features a collection of these top-performing strains for indoor growers in autoflowering varieties—Gorilla Glue, Bruce Banner, and GSC Extreme—so you can collect these top high-THC highlights all in one pack.

Available from ILGM as a mixpack.

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Be sure to check out your local laws and regulations on cannabis homegrowing before you start your adventures in cultivation.