NPK - Nitrogen, Phosphorus, and Potassium
Nitrogen, phosphorus, and potassium are the three primary plant nutrients you need to look in fertilizer. Nitrogen is essential for green vegetable growth, while phosphorus and potassium have several responsibilities from disease resistance to root growth and formation of flowers and seeds.
On every bag of fertilizer, you will see three numbers representing NPK ratio. The ratio needed for your soil primarily depends on the type of soil you have. A simple soil test can tell you more about characteristics such as PH (acidity or alkalinity), nutrient deficiencies, particle size, etc. These are all important features when making a decision what is the best fertilizer to use for the best results.
It is important to conduct a soil test and determine its nutritional requirements before purchasing fertilizers.