You're not alone if you're confused about what makes certain strains of cannabis more potent than others. The “potency” of cannabis refers to the concentration levels of tetrahydrocannabinol (THC), the main psychoactive compound found only in cannabis plants, present in a particular strain. However we must remember that each variety of marijuana – of which there are currently thousands – will affect every consumer differently. Here we will examine some of the most potent cannabis strains, which consistently test at least 20% THC, being grown today.

Northern Lights, OG Kush, Ice, Nexus OG, and Death Star are potent Cannabis indica strains. Kosher Kush has been winning Cannabis Cup awards since 2010, and this potent strain consistently tests at THC levels of more than 20%. Other potent indica strains of cannabis include Golden Lemons, Mr. Nice, and Stardawg.

Potent Cannabis sativa strains include Maui Waui, Laughing Buddha, Sour Diesel, Strawberry Cough, and Moby Dick. Ghost Train Haze won 1st Place Sativa at the 2014 Denver Cannabis Cup and is noted for its consistently high THC content. Willie Nelson's namesake marijuana strain is also a potent sativa that won the 2005 High Times Cannabis Cup.

Girl Scout Cookies, Tangerine Dream, and Gorilla Glue are touted as some of the most powerful hybrids you can find. Bruce Banner offers a consistently potent THC level of more than 28%, and it won the 2013 Denver Cannabis Cup before being rated High Times' 2014 strongest strain. Hybrid marijuana plants seem to be the future of super-potent cannabis strains as growers cross-breed more and more varieties.

Pinpointing the potency of a cannabis strain remains a tricky thing, in part because plants grown from seed may exhibit different characteristics from its parent. Also, if growing for yourself, note that your plants may produce higher or lower levels of THC than another grower's due to differences in gardening techniques and environmental conditions. To conclude, you have no need to fear the potency of any cannabis plant; not a single death from a marijuana overdose has ever been reported, but don't rule out a long nap after using any of these potent cannabis strains.