Marijuana can not mend smashed knees.
Nevertheless, it ought to be beneath the dignity of the State to regulate common weeds, except where they are an agricultural nuisance, like Russian thistle or knapweed.
Cannabis is not such a weed, and if it was, there are already such laws protecting farming and the environment.
The War on Pot makes the government look absurd - perhaps that’s a good thing!
Cannabis is actually very good for agricultural land. Its roots go deep and break up hard compacted clays, introduce organic matter a couple of feet below the surface and hold soil that is prone to erosion very tightly. When plowed under it introduces almost as much nutrients as stinging nettles so it’s a good cover crop too.