Let's see.
It's legal to grow the plant but it's illegal to have a plant with flowers. So, if you are growing plants for 'personal use' then what should you do if your plants decides to flower?
So, once signed into the Royal Gazette, I'm assuming those 3000 prisoners released on possession charges will be tossed back into jail. Then they better start building more jails because the commoners can now grow the plant, but should the plant flower they can then be thrown into prison.
Of course it's not too late to simple add another sentence to the bill that makes it illegal for the common public to grow that plant in the first place. Flip-Flop. Right back to square one.