I have mostly St Augustine grass in my 1.5 acre yard. I know that St Augustine has above-ground stolons and will grow horizontally over things. Currently the grass is everywhere, as I didn't put in any borders when I moved here, and I never used the weed wacker to create any borders, and the grass is getting into my pine needle tree beds. I'd like to put in a DIY permanent border, as cheaply as I can, and I'd like it to be as low-maintenance as possible.

The challenge is figuring out what kind of a border will do that, because if I wanted to put in a mower strip, the St Augustine will just grow right over that, unless I hedge all the borders regularly (maintenance). If I put in a tall enough border, say like 6" height or so, I don't think the St Augustine can grow over that, but it would require following up with the weed wacker around the edge of the border every time I mowed.

If border maintenance cannot be avoided completely, my choice would be a permanent border that the grass simply cannot grow over or in between or around, that I simply have to come back with weed wacker to get the tall grass up against the border that the mower couldn't get.

Anyone else have a low-maintenance border for their St Augustine?