Help with Meditation Labyrinth?

I tried building a meditation labyrinth in my game that is similar to one I saw IRL. I used lavender bushes to define the "walls" defining the path, but it didn't work the way I'd hoped.

A meditation labyrinth is not a maze. There is a single path that starts at the perimeter, winds its way around the maze, and ends in the center. My goal is to have a Sim follow that path from the outside to the center. However, when I use lavender bushes, my Sim just walked over/through the bushes, rather than following the path.

What is the least obtrusive, most "garden-like" thing I can use to define a path like this, and have the Sims actually follow the path? Lavender bushes weren't "wall-like" enough to work, even if that is what was used in the one I saw IRL.

For reference, I'm playing a vanilla game with no packs, cc, or mods (yet). And here's the simple labyrinth design that I based mine on.

Thanks in advance.