FloraDuo A 1 qt Q: What does N-P-K stand for on my nutrient? A: N-P-K is the abbreviated form of Nitrogen, Phosphorus and Potassium within a nutrient formula. The numbers labled on a specific formula represent the percentage of that compound. Ex. 2-6-6 is 2 percent Nitrogen and 6 percent Phosphorus and Potassium.