In Indiana, you would need a 'retail merchant certificate', because the plants would be taxable. You probably need some type of insurance, at least general liability. Also, in Indiana, if you sell 'woody' plants, like shrubs you need a 'nurseyman's license'. None of these are hard to get, do some research online, if you don't get answers for your area.

In Kansas you need tax id, can get it online and a nursery license. If you sell less than $10,000 it is free and there are no inspections. I don't need to worry about that. I only sell a couple hundred tomato and pepper plants each year. However, I have a piece of paper that says I can legally do it.

Jay

It'll vary by state. I had to have a vendor's license, and since I grow perennial stock, a nursery license and inspections. I also carry insurance. The exemption in my state is four hundred dollars before it's considered an enterprise.