These are our steps in a dry stack wall. You could also add something like this onto the front of the wall without actually disturbing it; you would only hide a portion of the wall behind the stairs. It would waste some stone but at least you'd be fairly confident of structure, as the wall would remain contiguous. KarinL

Don't leave the sod and topsoil. It contains some organic material which will eventually decompose and compress, leaving you with an uneven patio. Remove topsoil until you are sure you are in undisturbed subsoil, then start with the gravel and sand. If you can't compact with a motor driven compactor, flood with water and use a hand tamper. Dry stack walls are not usually great retaining walls, but if you have a good base, use interior mortar and make it thick enough, it should be fine. With an 18" grade change to support, the wall should be at least 2' thick. Old concrete is fine inside.

Jean, I live in Cincinnati, and have done it. It's a fairly low wall, filled with a sandy soil mix, and my Delasperma cooperi has done beautifully. In two years it has spread along about six feet of the top of the wall. It is in constant bloom from maybe June to frost. It is also very easy to take pieces and try them other places. D. nubigeum has survived on top of another wall but has never flowered. I don't know why. I've got several other delaspermas doing well in other places, but not in walls. They are, however, in soils that stay relatively dry during the winter. Wet soil, more than cold temperatures, in my opinion, is why these plants sometimes don't survive winter. Scott

I think it looks OK but you will probably topple over the bricks as you move around, in particular at the high end as you are reaching over to any plants near the corner of the 2 fences. Chance are it will topple over into any plants that are growing inside the bed there since you are moving in that direction. That would be my only concern. Otherwise, about 3 tall isn't overbearing enough to fall on its own. One way to get around it is to build the ground (and additional bricks to support it) in a kind of terrace design. For example, as you have now heard about Bartholomew, his recommendation is for beds that are about 4x4. This is so that you can reach many plants from the outside of the bed. If you split yours into roughly 4 feet (some go 3 or 5, depending on how they want to break up their bed size), then for the higher end, you will have a higher level of soil to use. Then with about a 1-2 feet path where you can access the bed on the right or the left, then start your next bed for another 3-5 feet width, but that one will have a lower level of brick wall and thus, soil depth. Judging by the number of bricks laid out, You could probably get about 2-3 beds plus a path or two in between out of that area, depending on the sizes you wanted.