1.) When is the best time to plant seed in the fall(Iowa)? Some say plant earlier so the seeds can adapt to the soil. Some say later... so seed will not dry up?
I don't know much about the climate in Iowa. However, I am much less worried about seed drying after it is in the ground than I am before it goes in. If you plant ginseng seed in a place suitable for it to grow, it will be just fine in the ground from the time the berries turn red (starts here in early Augest). In addition, we have learned that seed can tollerate being more dry than traditional wisdom would suggest.
2.) When will my plants start producing seed that I can harvest and replant. My plants are 2 years old now.
It all depends on the conditions where they are growing. Most commercial seed is harvested from 3 year old 3 prong plants (they pick the buds off the 4s the year of harvest). I've had 3 year old three prongs...and I've even seen seed on a 2 year old plant....but that was incredibly exceptional conditions. On the other side, I've seen 40+ year old 2 prong plants that might have never produced a seed. -It really does just depend.
3.) What is the best way to plant the seeds that you harvest?
Seed is seed. Green or stratified. Plant them all the same way about an inch deep. I would suggest you stratify the seed first though. You can make quick container for a small amount out of window screen and maybe some hardwire cloth. Fold the screen around the depulped (and maybe treated) seed and fasten it with staples. Then, if you need to protect from critters, wrap that in 1/4 or 1/2\" mesh hardware cloth and burry it about 8\" - 12\" deep in a place ginseng should grow. Take them out in August, or whenever you are ready to plant, bleach them, rinse them, and let them soak for a few hours or over night then float test them. If you stratify in the ground, you can normally skip the soaking part.
4.) How to get the best germination rate. Soil, shade, moisture,seed quality, planting methods- till, rake, etc...
That's the $64 question! You need all of those things for good germination, but all of those things can't always guarantee good germination. Experiment some. Find a combination that works for you and stick with it...and still don't be afraid to try new things or learn new stuff.
This is a learning experience for me.... and I enjoy watching my plants grow.
I think we all do or we wouldn't be on the forums in the off season. And, it should always remain a learning experience. When we stop learning, we start to die.