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).
A balanced fertilizer with an NPK ratio of 10-10-10 or 5-10-5 is a safe bet for most vegetables. Keep in mind that different vegetables have different needs, and their growth stage also plays a role.
The best NPK ratio for growing flowers will vary depending on the specific flower you’re growing and its growth stage. But in general, a balanced fertilizer with an NPK ratio of 10-10-10 or 20-20-20 works well for most flowers.