UBTrapper...
I think that the amount of light (and perhaps the type of light) they are getting (morning sunlight is best) makes the biggest difference in how big or tall a seng plant will get.
It there is too much shade, they will grow 50-60 years and not get any bigger than a 8-10" tall 3 pronger.
But if they are in good soil and getting lots of morning sun, in just 5-8 years they will be some big stout and tall 3 and 4 prongers.
I have a creek bluff not too far from my home that faces due east. There are locations on that bluff where I find just HUGE seng, nice tall 3 and 4 prongers with big fat bulby roots, and no more than 7-8 flats on the root neck.
Another example... in places where the ridge top has been clear cut, but the hollow bottom and hillside still has good timber... there will be more light getting down into the seng growing areas than normal... and that seng will grow much larger than usual.
I have a spot like that that I hunt every 3-4 years... and only part of that ridge top has been clear cut...
On the hillside down below the ridge top where it has not been clear cut, I find all kinds of normal-small ginseng plants - 8"-10" tall 3 prongs mostly.
But on that same hillside down below the ridgetop where it has been clear cut.. things change drastically. Lots of lush green growth, water weeds, polk salid plants, briars, etc... but SENG... BIG SENG. - big old tops and roots, lots of 4 prongers.
The increase in sunlight is what made the difference.
TNHunter