Renovation of a terrace with edging and rhizome barrier issue

What I just remembered. At least our rhizome barrier is buried about 60 cm deep. You don't have to dig that deep for the edging stones. That means the lower part of the rhizome barrier remains buried, it is not exposed at all. If your barrier is also that deep and you use regular edging stones. And since the barrier is closed in itself, it cannot slip away at the top if it is still firmly fixed at the bottom. At least ours would be far too rigid for that.

Yes, that is a good point. The rhizome barrier is 70cm deep and the curb stones are 25cm high. So, I will go about 40cm deep. However, I think I will still drive in 3 metal rods each time to be on the safe side.