Landscaping computer programs abound. I personally use VizTerra by Structure Studios for most of my projects. However, its learning curve is fairly difficult (but not as difficult as AutoCAD). One of the more simple programs that I use is Realtime Landscaping Photo, as shown in the two photos here. One can take a photo and manipulate it and place plants around it. It also comes with a landscaping program that a user can begin to work with to design from scratch. No one can be an expert with any program the first night, but instead of watching reruns on TV, working in landscaping software an hour a night will begin to show benefits quickly.
Add landscaping via software and help your customers visualize final designs.