Is it illegal to grow your own? It's the easiest way to get something low THC. Hell, you can even smoke (or better, use a dry herb vape) the leaves of any plant if the buds are too strong - from my experience, they have a more relaxing effect.
Depends on the state, even among those where weed is legal. WA has a pretty terrible duality - buying is very easy, and i like how that part was handled. Growing your own recreationally (i.e., not as a registered producer/manufacturer)? Not allowed at all, unless you are a medical user, and you are limited to only 4 plants.