"Although Ginkgo biloba and other species of the genus were once widespread throughout the world, its range shrank until by two million years ago, it was restricted to a small area of China.
For centuries, it was thought to be extinct in the wild, but is now known to grow in at least two small areas in Zhejiang province in eastern China, in the Tianmushan Reserve. However, high genetic uniformity exists among ginkgo trees from these areas, arguing against a natural origin of these populations and suggesting the ginkgo trees in these areas may have been planted and preserved by Chinese monks over a period of about 1,000 years. This study demonstrates a greater genetic diversity in Southwestern China populations, supporting glacial refugia in mountains surrounding eastern Tibetan Plateau, where several old-growth candidates for wild populations have been reported. Whether native ginkgo populations still exist has not been demonstrated unequivocally, but evidence grows favouring these Southwestern populations as wild, from genetic data but also from history of those territories, with bigger Ginkgo biloba trees being older than surrounding human settlements.
Where it occurs in the wild, it is found infrequently in deciduous forests and valleys on acidic loess (i.e. fine, silty soil) with good drainage. The soil it inhabits is typically in the pH range of 5.0 to 5.5."
Also, this is a pretty concise lil pdf treatise as well:
Seems like Anne is spot on though, if it like a low pH like that, it would likely appreciate a good amount of organic material, i.e. an established forest. There are lots of black locusts around here, maybe I'll find an existing grove and plunk a couple seeds down in the fall. Hot tips, y'all! Thanks!