Here are a few pictures of how I addressed one spot on my “old” railroad, I had about 8-10 planting locations scattered over the railroad.
I built a box and hung it down from the table top using Cedar fence boards and metal straps then lined it with a double layer of good quality weed block cloth. then used chicken wire to build up some
hilly shapes and covered them with a stucco mix that had burlap strips dipped in it.
Here the boxes have been filled with planting mix and the shrubs, ground cover, and sprinklers planted.
The shrubs/trees were left in their pots to control growth but the top rings of the plastic pots were cut off so the
wouldn’t show above the fill dirt.
Another view of the same area after the “hardscape” work was done and before ballast. As you can see in the pictures I am not a fan of “letting the track float”
on a table top installation, just didn’t work well for me.
Just be sure to build your containers large enough that they contain enough soil to control freezing roots and drying out roots.
Have a ball building.