Its like finding a needle in a haystack...unless you know of a hayfield with needle laden hay bales. Take the time to research ginseng habitats and companion plants. A few years ago I knew nothing of ginseng. I have since learned the names of all native trees and understory plants and now I can reliably find ginseng whenever I want to, even in new places. I don't dig it, I just really enjoy hiking and trying to find it.
I am in western PA by the way.
North facing hill, under mature trees with thin leaves that decay easily such as poplar. This provides a constant replenishment of organic matter. The understory that I find it in is also usually pretty open. 15/200 is not a terrible germination rate. The soil that I find it in is loose as squrlhntr said, and it gets that loose character because it is composed of the eroding sandstone rocks that dot the mountansides here making it seem sandy.
I bought the seed from Johnnys Seed company. The first shipment I had two plants come up and wrote to them They sent more in the fall and from this I got about 10 plants. It is in the woods next to a large rock. I have some poplar but didn't plant any there as I thought they would get too much light. There is plenty of organic matter for them to grow just such poor germination and the plants are very small and spindly. I did try some Miracle Grow and it didn't seem to help much.