I have several wildflower patches that I never mow and they look great. Not as good as they would if I took the time to "do it right" but it is good enough. Thing to remember is that a wild flower patch is not going to look good for the first couple of years because a lot of the plants are concentrating on root growth and not flower production. What I would recommend for you is to look up the most aggressive wild flower species for your area and plant heavy with that along with a good mixture of annual seeds for the first couple of years to keep the mrs. off your back. The annual seed are usually inexpensive and will keep it colorful while the perennials are maturing. I have several customers who have berms that they just disk up in the spring and replant with annuals every years so they do not have to fight it. I usually check my areas a couple times a year and hit the unwanted with herbicide.