Grounds keeping

[Whowefoolin]

How can someone get certified to be a grounds keeper? A lot of people (i.e., city, coaches, owners, etc...) won't let anyone but them touch their fields. I understand this. But when they don't do the job, how can someone convince them that they can take good care of it? Is there some place to go and get a certificate to show that a person has the proficiency to grounds keep?

Thank you in advance.