[header] How to install plastic lawn edging [title] Use a sod-cutting spade or tree-planter's dibble to cut the lawn in the desired shape of your flower bed. [step] It is most effective to make the cuts straight downwards (vertical), as this will provide the proper angle for the lawn edging. Push your spade down below the level of the grass roots (at least 10 inches). 
Now, lever the handle of your spade downward to lift up the sod you wish to remove. This completely loosens all of the grass roots.