Use regular AV soil and fill the container about half full. Start landscaping by pushing the soil up in the back and placing something there to hold it. I have a moss-covered piece of wood that makes a nice wall. Plant a tall plant in the back portion of soil. Closer to the front, make the soil line smaller than the back and plant a few smaller plants, ivies, ground covers others. Rocks can be very effective lying flat or on the side for height. Next place your African violet(s).