If you can take that garden plant, and develop a patentable process to extract or modify the contents of that plant into a drug, they will work to develop the drug if a business case can be made for it. Hey, if you're good enough, maybe you could grow it and produce the ingredient for your own use. You just couldn't sell it legally.
That's why I said Kimmio was 50% correct. They aren't stopping you from growing plants and producing it. They're stopping you from selling it.
Again, you don't understand the business side of it. I'm not an expert, but I get the gist of it. I've been around drug and testing development. I was heavily invested in drug development just last year. The motivation for drug companies is the development of proprietary knowledge and compounds that they can keep away from
generic manufacturers for years by way of patents. It's about patents and the prevention of competition.
No patents? Say goodbye to a lot of very good drugs.
Don't like the system? A lot of people don't, myself included. Propose something better. Ideally something that still gets drugs developed. Not easy, is it?