When choosing a fertilizer for St. Augustine grass, it is recommended that homeowners run a soil test to determine how much phosphorous and potassium is in the soil. If there is an abundance of these two elements, the grass simply needs nitrogen and can maintain a healthy appearance with 10-0-0 or 20-0-0 fertilizer.
On a package of fertilizer, there are three numbers. The first is the fertilizer's nitrogen content. The second is phosphorous and the third, potassium. The higher the first number, the higher the nitrogen content.Learn more about Gardening & Landscapes