Ours are pretty dumb that way too, I think our limit is 30g dried pot, or 150g of what they call "fresh" (wet) allowed to be carrying in public. At home limits vary from province to province, but for the most part they're not much better.

The laws were obviously written by people who have no idea what they're doing and don't make much sense. A couple good plants can easily make more than the limit. I've had pot plants taller than I am. The only good part about that is the cops don't really care, so unless they're looking to screw with you it's not a big deal.