An easy way to remember what the three different numbers mean in a fertilizer formula is through the simple phrase: Up-Down-All around.
The first number is the percentage of nitrogen in the mixture. Nitrogen aids in the growth of green, leafy upper portion of the plant. The “UP” part of the phrase.
The second number is the percentage of phosphorus in the mixture. Phosphorus aids in the growth of strong root systems. The “DOWN” part of the phrase.
The third number is the percentage of potassium in the mixture. The entire plant, leaves, roots etc. use potassium. The “ALL AROUND” part of the the phrase.