I can’t really tell, but if looks to me like you need another retaining wall at the sidewalk. Isn’t there still quite a height difference between the sidewalk and the new low wall? What’s to keep that soil from washing down on the sidewalk?

No, we are good there, but thank you for the comment. The pic may be misleading - any other suggestions? Thanks!

Hmmmm. Well, there’s no way to give any planting advice without knowing where in the world you are located. California? Australia? Nova Scotia? Costa Rica?

Christopher, thank you for your comments - btw we are in California so warm summers, mild, wet winters. On the lower ledge would you do one or two rows of Cotoneaster dammeri 'Streib's Findling',?

One row. Each plant can cover many square yards. You’ll need to keep it cut back from the sidewalk. In fact, for that reason I’m not really convinced it’s a good choice. Maybe something like a Cistus would be better. You could have another row along the top if the wall. Or use the Cotneaster along the top. It’s one of the few shrubs which will grow downwards. Not just hang down but grow downwards.

'Streib's Findling' has nothing to do with Cotoneaster dammeri, is so similar to typical C. procumbens that it may be most apt to consider it such. In either case (C. dammeri or C. procumbens) we are talking about very low shrubs that will have no ability to deter dogs or human foot traffic. And would need to be checked for local climate suitability in California (try a later edition of the Sunset Western Garden Book). With fire blight being a potential chronic and ruinous problem with cotoneasters planted anywhere temperatures above 70 degrees F. occur regularly in May.

In addition to the soil migration issue - already I see some of the footings for the wall support posts sitting high, because of the differential between where they are and where the bottom of the slope is - if the bed is left wide open to the sidewalk, with no barrier where the two meet there will be random and recurring wandering into the bed by animals and humans. Depending on what the specific makeup is of the local human population this unprotected large bed could now become the new great spot to bring your dog by people who do not pick up after them. It even has a fence to keep them hidden from the property owners while they are at it.

Now that people know it is California, the choices of non-jungley woody sub-shrubs has greatly expanded from the two I offered. I'm guessing central to northern Ca. You could dial it in for us and get very climate appropriate suggestions. It would be quite easy to kick up the wow factor with blooming plant choices for your area. And since it is such a large and long space, some key accent plants in the low woody flowering groundcover layer would be a nice addition.

I'm a cat person who puts cement lions in wild spaces. What do I know about a dog's pooping parts?