NPK stands for nitrogen, phosphorus, and potassium: the three primary macronutrients that plants need to grow strong and healthy. These three nutrients are found in most fertilizers and are important for different stages of plant growth.
On a fertilizer package, you’ll see NPK represented by three numbers, such as 10-5-5. These numbers represent the amount of each nutrient by weight, expressed as a percentage of the fertilizer.
For example, a 10-5-5 fertilizer means you’re getting 10 percent nitrogen (N), 5 percent phosphorus (P), and 5 percent potassium (K).
So, a 10-pound bag contains 1 pound nitrogen, 1/2 pound phosphorus, and 1/2 pound potassium. The remaining weight is composed of secondary macronutrients, micronutrients, and fillers, which give the fertilizer bulk and make it easier to spread.
Choosing the best fertilizer for your plants can be a bit tricky, but with a little bit of knowledge and some simple guidelines, you’ll be able to give your plants the nutrients they need to grow healthy and strong.