



Phosphorus fertilizers. You can buy fertilizers with a high phosphorus ratio, but you can also fortify your plants with bone meal, which contains 20 to 25% phosphoric acid and has an NPK ratio of 3-15-0. Fish bone meal is another high phosphorus fertilizer — you may find it in a 4-17-0 ratio. Tetra Images, LLC/Alamy.













































The letters "NPK" on a fertilizer label stand for nitrogen, phosphorus, and potassium, the three primary nutrients plants need to grow. The numbers on the label indicate the ratio (by percentage) of nitrogen, phosphorus, and potassium in the fertilizer container. Even if you do not see the letters N-P-K, but you see a set of three numbers, …


