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 expressly 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.
The Importance of NPK Not all types of plants have the same nutrient requirements, and you can sometimes do more harm than good when applying chemicals haphazardly. Applying a fertilizer high in nitrogen will cause certain plants to put all their energy into producing foliage at the expense of flowers.
If you do not have a good grasp of how well your soil is meeting the nutritional needs of a plant but still feel the need to feed it at a particular time, you should try one of the following options.