Most seminars, presentations, articles, and even semester-long courses about turfgrass nutrition discuss the functions of different elements. Potassium is involved in stomatal regulation, phosphorus is essential for root development, calcium for cell wall strength, and so on. All true, but largely irrelevant for the turfgrass manager. What the turfgrass manager must know is not the function of each element, but the quantities -- is enough of this element present to meet the grass requirements, or is it not? If it isn't present in adequate quantities, how much must be added to ensure the grass has enough? In this seminar, the fundamentals of turfgrass nutrition will be explained, with a focus on an understanding of the amount of each nutrient that is required.