Choose the Right Fertilizer: Know What the Bag Numbers Mean

Do you know what those numbers on the fertilizer bags mean? Most people don't, and tend to choose a bag of fertilizer that has even numbers across the board, such as 10-10-10, or go by the recommendation of a seasonal, unskilled salesperson.

Choosing fertilizer with the wrong numbers for your flowers, lawn or vegetable plants could result in more harm than good. Let's break down those numbers, find out what each number means, so you can choose the right fertilizer for your growing project.

The numbers on the fertilizer bag tells you the percentage of the three major nutrients, nitrogen (N), phosphate (P), and potash (K), in the product. That is the sequence of the nutrients and the corresponding number on the bag, and will always be in that order, N, P, K.

Each of these nutrients effect plant growth differently, the formulation of fertilize that you choose depends on your specific growing needs.

Nitrogen (N) promotes vigorous plant growth for all flowers, vegetable plants and grass. Nitrogen produces more plant leaves, helps produce a darker green plant color by encouraging chlorophyll formation, and nitrogen is also a building block for plant protein.

Phosphate/ Phosphorus (P) stimulates healthy root formation in flowers, vegetable plants and grass. Phosphate helps flowering plants reach maturity earlier, increases the plant's flowering ability and increase the size of the blooms.

Potash/ Potassium (K) promotes fruit and vegetable formation, strengthens the plant tissues, and is essential for photosynthesis. Potash also increases the plant's resistance to disease and increases the plant or tree's ability to survive the cold winter months.

In most cases, you will want the fertilizer with the highest first number, the fertilizer that contains the highest percentage of nitrogen, such as a 24-8-4. A bag of fertilizer that only has two numbers, such as 20-0-20, is an incomplete fertilizer because it is missing one of the three major nutrients, but is useful in certain growing situations.