I have 607ft2 of beds that I want to plant wave petunias and vinca in. What do I divide 607 by to get my # of plants? If I divide 607 by 1 that gives me 607 plants. I will be using 4" and there are 18 to a flat. This give me a total of 34 flats, is that right? Sounds like a lot. Should I raise the # from one to 2 or 3? Thanks for your help!!!!!!!!