I do not understand a minimum charge. You guys would never get any work here in Houston. Our average residential is $30 a week and that is for mowing, edging, trimming, hedge trimming as needed, and raking and weeding flowerbeds weekly. You have to know your cost's to make money in this business. I do many yards for $25 also.
If I were you I would not raise your rates. You are destined to loose customers if you do that. I have been doing some yards for 3 years and I have not raised the rate once. You can't. Just treat them right and they will treat you right by giving you mulch and landscape work. I wouldn't raise your rates. Just asking for problems if you do. It's better to have $25 rather than $0
Ford and Chevy Trucks
Scag, Exmark, Wright, Toro, Snapper
Echo, Stihl, Shindaiwa
Lesco application equipment
Having employees that enjoy what they are doing and care about quality is what makes happy customers.