Hi Fenris, welcome to the forum.
I've seen ginseng growing anywhere the proper conditions are present. For instance, traditional knowledge tells us to look for it on northeast slopes. This is true as conditions favorable to ginseng are often found on northeast slopes. But, I have seen ne slopes where you can't grow ginsent, and I am currently planting on a southwest slope. I've found a lot of ginseng on west facing slopes because all the conditions for it to grow were there. The major worry I have about trying to grow it down low in the valley is it getting too much ground water. Mind you I have indeed harvested some pretty large ginseng plants at the bottom of a valley, however.
The conditions the ginseng is grown in is what changes its price. Cultivated is cultivated. Woodsgrown is woodsgrown, and wild is wild....mostly. If you plant wild sim, your ginseng will be for all intents and purposes wild and bring wild price for its quality at the time of sale.
I never encourage spring planting. Ginseng is a perennial and as such it seeds in the fall and comes up in the spring...not the next spring...the spring after that. That is why it is important to buy stratified seed which will come up the next spring after fall planting.
As a dealer, my first suggestion to you is to not dig those small plants in the first place. I hear a lot of guys say you don't know how big it is until you dig it. This is true. But, you can certainly put it right back in the hole and cover it up again. That said, there is nothing wrong with harvesting legal plants and transplanting them into seed producing beds or areas where there is little ginseng. I often do that with smaller green roots in lots that I buy.
There are several of us here who will be happy to answer your questions as they come up.
b