True G-13, or Government Indica Strain 13, is a pure Indica strain that is legendary for it's origins after appearing sometime in the 70's or 80's. After years of cross-breeding, however, the current G-13's generally found in dispensaries are likely not a pure Indica, but rather lean heavy on the Indica side. 70 percent Indica and 30 percent Sativa would be a more typical breakdown of today's G-13 labeled strains.
It produces a very powerful body stone typical of Indica strains that will make users feel lazy and lethargic. Despite being a very heavy Indica, it also has strong cerebral effects that are most often described as euphoric. More experienced users claim this strain makes them more focused and creative before the "couch-lock" feeling seeps in. The strain also possesses typical downsides associated with high THC content Indica strains and those are: dry mouth and eyes, dizziness, paranoia and some anxiety.
This is a good Indica strain that can be used to medicate all throughout the later part of the day to ease chronic aches, pains and muscle spasms. G-13's mood elevating effects may help battle stress, anxiety and depression related disorders as well. Some find that it helps them with insomnia, allowing them to sleep throughout the night. It is also used by patients to combat the effects of eating disorders, seizures and nausea.
G-13 supposedly came from a research facility in Mississippi where, with help from the University of Mississippi, they were using pure Afghani Indica clones to try to create a super Indica strain in the 60s and 70s. As the story goes Neville Schoenmaker convinced someone working there to bring him a cut from one of the strains, which were labeled G-1 to G-23. G-13 was the most stable strain they had and the one chosen. This strain flowers for six to eight weeks to produce a reportedly high yield and works very well in a Sea of Green. Unfortunately true G-13 is a rare find as it is available only in clone form.