Fact: This strain (originally a single clone) was probably of Afghani origin, and provided a very potent smoke.
Fiction: According to one fanciful account, the CIA, FBI, and other agencies procured the best strains of marijuana from breeders all over the world. At an installation at the University of Mississippi, they bred many new hybrids. Putting these together, they created a strain that was more powerfully intoxicating than any of the original hybrids.
Fact: Although Cannabis researchers at "Ole Miss" assembled a world class Cannabis collection during the late 1960s and early 1970s, there is no evidence that these researchers were ever involved in breeding high quality marijuana. The standard drug strain that is available to qualified researchers in the U.S.A. was originally from Mexico.
Fiction: Apocryphally, G-13 contains 28% THC by weight, about double the average percentage in most high-grade sinsemilla grown commercially. It has been claimed that some strains of marijuana grown in Amsterdam have met or surpassed this percentage, but accurate, verified results have not been produced. Also, no other species of the plant seems to have quite the consistancy of such high THC content.
Fact: Cannabis researchers identify G-13 as an Afghani "indica" (or 'Afghanica') cultivar, high in THC (though not as high as the 'apocryphal' estimate above).
Reports of THC/cannabinoid content exceeding 20% are invariably from sellers of Cannabis or Cannabis seeds, or from anti-Cannabis crusaders.
Reliable testing has placed the most potent examples of Cannabis plant matter ever tested at around 18% or 19% (based on Dutch government testing of medicinal grade Cannabis)
Unsubstantiated Rumors: Allegedly, a single cutting of this potent strain was "liberated" from the government facility in Mississippi. Other rumors say G-13 was developed by the university of Washington Cannabis testing facility for medical testing during the 1970s, but this too has not been verified.
In the early 90's, the name G-13 was said to have come from the number of [backcross] generations it took to produce an almost perfect plant - however, this view has absolutely no basis in reality.
The name G-13 is was derived from the term Government Marijuana, the 13 used as M is the thirteenth letter of the alphabet.
The most common story about the naming of G-13 is that it was stolen from 'grow-room 13' and simply retained its lab ID code.
Another fantasy-based rumour is that the name 'G-13' derives from the 'genotype' having been created to express 'the 13 most desirable qualities'. Again, this is just idle (and poorly thought out) rumour.
Some seed banks (which are very unlikely to have genetic material from the original clone) describe this strain as the highest THC content ever. Other seed banks that are known to have actually worked with the clone since the mid-Eighties describe it as one of the strongest "indicas" ever discovered.
G-13 in the Movies
The G-13 strain was featured in the film American Beauty. In the film, a young dealer named Ricky Fitts (Wes Bentley) hands a bag of what looks to be about an eighth (1/8 of an ounce, commonly 3.5 grams) to Lester Burnham (Kevin Spacey) and says, "This shit is top of the line. It's called G-13. It's genetically engineered by the U.S. Government. It's extremely potent, but a completely mellow high. No paranoia." He then charges him $2,000. This line is likely responsible for a boost in the strain's popularity.
However, the actual dollar value of G-13 (non hybrid) ranges from $20.00-$25.00 for a single gram, equalling about $60.00-$85.00 for an eighth of an ounce.
G13 gives a high unlike any other cannabis strain available. The onset is almost immediate, with noticeable effects occurring within the first five minutes. Most users who have never had the chance to indulge in this strain are awe-struck when they first experience it. While most cannabis strains will have a "peak," in which the high starts to wear off, this does not occur with G-13 (in a manner of speaking). Some people have described G-13 to be "an elevator that never reaches the top floor," meaning the high keeps going up, and up, and up and does not stop. Many users also report a great euphoria as well.