If cement will stick to it, you can use it in your garden wall. Now wood doesn't stick, but if you leave the screws sticking out an inch, they do stick.
This has a steel base for the hand rail riser that the little wall was built around.
This rock wall is about 3 foot tall. Some of the rocks are only a couple inches across. But it's still there.
This was a pretty good sized Coast Live oak. Beautiful wall, dead tree. Do not change grade around trees. Leave the area under the tree alone. If you look up and see leaves, you are under the drip line.
This wall killed three full sized oaks. The people are gone, but so are the oaks.
I didn't do it! The combined iq of the people that did this is lower than our average daily winter temperature, in Celsius.
Railroad ties work well. Use some nails or screws hanging out the back to anchor the steps, or drill two holes through them and drive rebar into the ground.