The most common type of fertilizer is the 10-10-10 mix, with all parts equal. In the Coastal Bend region, soil should be tested every two to three years to help determine the exact mix of numbers.

The most common type of fertilizer is the 10-10-10 mix, with all parts equal. In the Coastal Bend region, soil should be tested every two to three years to help determine the exact mix of numbers.

Knowing your fertilizer numbers can save you water and mowing time, especially in hot and humid climes such as that of the Coastal Bend, where grassy lawns are easily stressed.
The three numbers on a fertilizer bag are the NPK numbers. Those numbers represent the amount of nitrogen, phosphorous and potassium in each different mix. Think of it as "up, down and all around."
As the first number, nitrogen also is the most important. It is the "up," as it aids in photosynthesis and development. Too much N in your PK causes your lawn to grow too fast, meaning you'll have to mow more. You'll want a balance that keeps the blades green and thick, but not necessarily long.
The second number represents the phosphorous, or the "down," which helps plants develop strong root systems. It also promotes flower and fruit development in plants.
Potassium, also called potash, helps develop healthy, disease-resistant plants, which is why it is referred to as the "all-around." It also protects against excessive water loss, which is why a higher third number is often good for drought-stricken areas. 
The most common type of fertilizer is the 10-10-10 mix, with all parts equal. The rest of the mix is filler, usually made up of granular limestone or clay pellets that help disperse the chemicals.
In the Coastal Bend region, you should test your soil every two to three years to help determine you NPK mix before fertilizing, recommends the Texas Cooperative Extension division of the Texas A&M University System. Any local garden center can test your soil and offer advice on the right mix. First, determine if you want a low, moderate or high-management lawn before deciding on the mix.
For a low annual program, apply once in the spring and once in the fall. Apply one-half to one pound of fertilizer per 1,000 square feet of lawn. Several of the local lawn care companies can provide you with a custom mix of fertilizer along with custom treatments for insect and weed control.
Trees and shrubs should get one deep root feeding in the spring with a time-release fertilizer.
When fertilizing the lawn, water thoroughly a day or two before applying the fertilizer. Once the grass is dry, apply the fertilizer then water again to wash it off the grass and into the soil.