I think it is best to plant seed in the fall - in the September, October, November timeframe (would be my first choice).
I have planted in Dec and Jan myself and did not have very good results (low germination rates). I have never planted later than that or in the spring months.
I know some here do and report success with it.
I think when seeds are ready... and as soon as possible after seed producers pull them from stratification, they need to be planted.
The longer they are kept in some type of temporary storage, (like in the fridge)... the less likely they are to be successful, or more likely they are to develop problems. They are sensitive to temp, and moisture levels... and well nothing really holds them good like good ole mother earth does.
If you have already ordered seeds.. then good luck with them. I would recommend if you are going to try spring planting, then start out slow, small amount and see how it does. If successful for a year or two then you can go with higher quantity of seed to plant.
It really takes 3-4 years to get a good idea of what will work and what will not, and that varies by site some. Good Luck figuring it all out for your location.
I have had low gerrmination from early spring planting as well. However, sometimes you are going to want to do that due to time constraints, etc. You will want to do the ground prep when the ground isn't frozen, tho! Which is to say, planting when the ground isn't frozen is a must as well! [smiling!]
As TNHunter said, there are others that plant in the winter, and have excellent results.
Not going to be doing any ground prep I'm just seeding likely spots along a hill where ginseng has grown can't really mark it or make it obvious due to various people who can't read no trespassing signs so ill get what I get,just want to see a big patch in the woods sometime,will see what happens.
Spring planting I like to till the ground a bit toss in seeds and use a garden rake to lightly coves seeds other then that I leave them be if you take your time in the spring you should do just fine I have had good results both way. Planting in the fall to early with a warm streak can dry out seeds before the leaves fall. You have to be on your toes with ginseng