This is exactly what my gardener did. One day someone went to my home and started mowing it. I watched. After 4 months of free mowing, he started doing my hedges. I started to talk to other people in my house: "hey we should hire this guy". My wife said "wtf for, he is free? right?" Eventually, I was worried he would start doing free work somewhere else so we hired him - but not for much. He is a great gardener. /s