Crazy as it may sound, the state of Michigan requires a special license for anyone who wants to sell certain flowers. The small-scale Nursery Grower license is mandated by law for anyone who wants to sell perennial flowers that they grow themselves. The license costs $40 and the growing operation must be inspected annually by the Michigan Department of Agricultural and Rural Development. That costs an extra $59.
So, even trying to sell a single perennial flower means a person is out about $100, plus the time and expense to figure out and complete the process.
The reason for this law is to prevent the spread of pests and plant diseases. It’s a statute from 1931, the Insect Pest and Plant Disease Act. But a license and inspection fee is unlikely to help stop invasive species. If that is the goal, it would make more sense to focus only on inspecting plants brought in from outside the state.
On top of that, there are other exceptions. Plants and perennial flowers dubbed “wild” are not subject to the rules. Selling trees, flowers, or other plants from your property, provided you didn’t plant them, doesn’t require a license. Apparently, according to Michigan law, wild plants are less likely to convey disease and insects than perennial flowers grown in a controlled environment by someone with a strong profit incentive to make sure they are healthy.
For more information: 
Mackinac Center
(989) 631-0964
mcpp@mackinac.org
www.mackinac.org