Ginseng in San Francisco

I'm interested in growing Ginseng in California just north of San Francisco in the wine country. What challenges will I encounter in the attempt to grow it here and what possible artificial or cultural practices could I use to successfully grow it? Also, which, if any, of the varieties is most easily grown in my area?
I have lots of good info on how it is cultivated in general, but I hear it's finicky about climatic conditions. Can it even be grown in warmer areas?

Whenever I have told someone that they can't grow a particular plant in a particular area they have proved me wrong!
American and Asiatic ginseng can both be grown in zones 4 to 8. As far as I can tell from hardiness maps, the area north of San Francisco should be zone nine. It is therefore too warm for ginseng to survive there easily. You could try increasing the shade and the depth of the mulch to keep temperatures down. Maybe continuous misting on very hot days until the cooler evening might help.
Siberian ginseng is hardy in zones 3 to 8 and will pose the same problems as the other two species.