I'm sorry, I don't understand. You want something to plant behind the wall that will eventually flow over it?

@marie: I want something to plant behind the wall that would discourage children from stepping onto it from the grassy slope. The plant could flow over or not; I think I prefer not but if it looked good I could go with that. Thanks.

If I were a child, it would take more than some plants to keep me off the wall. I might not jump off into bushes, but I'd keep climbing. I'm serious. Are these your children? If you weren't looking I'd play on the wall. That wall screams "climb on me!". Pots might be more of a deterrant (and knocked off if the kids are determined to have fun) Or prickly bushes as first suggested.It would be nice to have some texture to soften the hard angles. This is challenge for experienced designers.....

There isn't much that will keep kids from going up the steps of that wall. If you are in a state where the laws are on the side of the ignorant like California then I would be concerned about your "attractive nuisance". If you are, then I would build a fence on the edge nearest the drop off. If not then a dense hedge should be sufficient.

We had this same 'attractive nuisance' type wall at church and no matter what we did the children would climb and walk on the wall and it was higher than yours. We had to install a fence with an 'L' extension of fence over the steps to keep them off. And we still have them swinging around the 'L' and walking on the fence--uggg. I would go with some type of very prickly holly for sure.

uh . . . wow. I'd climb on that, too! Hella fun.

rectangular planters matching the dimensions of each "step" filled with plants.

ETA: I think I would compare the cost of planting whatever you are thinking of (and the cost and time to maintain the plants) to simply redoing the top of the wall to be curved, and thus less obviously step like.

Yeah, I'd be climbing all over that wall too. Holly, berberis or roses might work. Or stinging nettles, those are always fun to run into.

I also thought of a curved wall. But some little physically active demon would still be using it as a balance beam.....fall offf....concussion....broken collar bone or arm.....days gone by it would be the price of being a kid....now homeowner likely to get sued....