NPK stands for "nitrogen, phosphorus, and potassium," the three nutrients that compose complete fertilizers. You may encounter these letters when reading the contents printed on bags of fertilizer. The description of the fertilizer may not expressvly say "NPK," but you will at least see a series of three numbers. These numbers correspond, respectively, to the nitrogen content, phosphorus content, and potassium content of that fertilizer. Also implied is a percentage symbol after each number because each of the three numbers represents the percentage of that nutrient in the makeup of the fertilizer. Most Ideal and commonly used ratio for NPK fertilizer is 19:19:19 .
It's a chemical fertilizer so don't use it on Fruits, herbs &Vegitable Plants. Works wonder for all kinds of ornamental and flowering plants.
Dosage : Application of this fertilizer crystals is very easy and depends on the size of the pot. For Larger pots of 16 – 18 inch diameter, you can use 1 tea spoon of NPK powder in 1 litre of water, once, every 15 days.
For 12 to 14 inch pot diameter, you can use aroundhalf tea spoon in 1 litre water every fortnightly. For smaller pots, About 1/4th of spoon should suffice. If your plants are in ground soil, you can use little larger quantity without any issues.