Such relationships between nitrogen (N), phosphorus (P), and potassium (K) and the development of specific organs underlie the reason for printing three numbers, the N–P–K ratio, on packages of fertilizer. For lawn grasses and most houseplants, recommended fertilizers have a proportionately high nitrogen content to promote leaf growth (20–5–5, being one example: 20 parts nitrogen to 5 each of phosphorus and potassium). Whereas a product having a 0–10–10 ratio is a typical formulation designed for flower and fruit set. A fertilizer for root crops may have an N–P–K ratio of 2–12–10, and an
...more
