Keeping that perfect edge on tree wells

[MattBinford]

I'm just wondering how each of you keep clean edges around trees/flower beds/wells. I have tried my Stick Edger with no luck. It seems the only way to keep a clean edge is with a string trimmer. But even then it takes alot of training for a new employee to get it right. Looking for alternatives. There must be an easier way.

Thanks,
Binny