Might be your soil. The soil here in the PNW is quite acidic, and the plantains grow all over.
So acidic that I have to put out alot of dolomite if I want decent tomatoes and such. Most plants prefer soil that’s a bit alkaline, maybe plantain is different.
It is alkaline soil and water here.
And this lot has poor soil on it, the wind blows any thing you add to it away.