Last fall I came up with the idea of comparing actual growth to ideal growth to get a ratio of growth. I called this tool the turfgrass speedo . Ideal growth was calculated using the growth potential formula on my weather modeler spreadsheet and would use the ideal monthly nitrogen rate to determine how much grass should be harvested based on actual conditions not just a date on the calendar. The idea was to growth the grass at the right speed, not just as slow as possible. Growing the grass too slow is worse than growing it too fast. When you grow it too fast you get excess thatch and have to mow it more but when you grow it too slow it can't handle the traffic or stress of any kind really. I had made all sorts of observations about growth in the past and the model seemed good. This winter I started a new job at a new course and was excited to see how the model worked at a different course. For the first 5 months of the year the model was working perfectly. It suggested growth was