Successful Lawn Fertilization in Texas
By: Joe Feather, Woodlake Outdoor
The quality of a lawn is usually measured by turf color, its density / thickness, and uniformity of growth and coverage. Fertilization is a key component in determining lawn health and appearance. Here are some Texas-specific fertilization helps.
First Things First: Know Your Soil
To address the specific needs of a particular lawn, a soil test is highly recommended. Although the grass will eventually manifest signs of nutrient deficiencies, soil testing enables you to address the need before the lawn exhibits such symptoms – solve the problem before it’s a problem.
The soil test analysis provides information on levels and availability of the macro-nutrients nitrogen, phosphorus, and potassium. This is key to measuring accurately the required nutrients for a given lawn. Some soils already contain adequate levels of phosphorus and/or potassium to maintain turf grasses. Further applications of these nutrients will not improve the quality of the lawn, and may actually harm it. Additionally, excess phosphorus entering the surface water can create an increase in algae and other undesirable plant growth.
Simultaneously, be mindful not to over fertilize – too much nitrogen, for example, will stimulate excessive leaf and stem growth, thus increasing the need for frequent mowing. Excess nitrogen also creates thatch layers, insect and disease susceptibility, and increased (and unnecessary) water requirements. Reference the Texas A&M agriculture extension for information on how to collect and send in a soil sample. In the absence of soil analysis, for a Texas lawn apply a fertilizer with a 3-1-2 or 2-1-1 ratio at a rate equivalent to 1 pound of nitrogen per 1,000 square feet.
In addition to nutrient levels, soil testing addresses additional variables critical to turf success. Soil acidity, soil salinity or alkalinity, as well as valuable information on amendments needed to balance the pH are contained in the analysis. Clay or sandy soils also have a dramatic effect on turf grasses. Sandy soils require more frequent applications of fertilizers than those growing on clay soils, as its small particles cannot hold nutrients efficiently. Clay is very fine (though dense) and holds the nutrients longer in the soil substrate, but as it also retains moisture, it is possible to rot/suffocate the root system.
Laying It on the Line: Know Your Numbers
On each bag of fertilizer, the macro-nutrients are listed as three numbers on the front of the bag (such as 15-5-10), and are referred to as NPK. The numbers represent the amount of actual nutrients in that particular fertilizer. The first number represents the percent of actual nitrogen (N), the second actual phosphorus (P2O5), and the third actual potassium (K2O). A quick way to remember the main benefit of each (respectively) is the old gardening adage, “Shoots, roots, and fruits.”
Grass Is Always Greener: Know Your Grasses
Grass species differ in fertilizer requirements. The three most common lawns for Texas are Common Bermuda, St. Augustine, and Zoysia. The nitrogen requirements for these are:
- Common Bermuda: 4 to 6 pounds of actual Nitrogen per 1000 sq. ft. per year
- St. Augustine: 2 to 5 pounds of actual Nitrogen per 1000 sq. ft. per year
- Zoysia: 3 to 5 pounds of actual Nitrogen per 1000 sq. ft. per year
Conditions such as rainfall, shade / sunlight also influence the fertilization requirements. High rainfall areas require more total pounds of nitrogen per year than grasses grown under drier conditions due to leaching of nutrients. Heavily shaded areas should not be fertilized as much as areas in full sunlight.
Bermuda grass lawns will require additional applications of nitrogen at 6 to 8-week intervals between the regular spring and fall fertilizations. These applications should not exceed 1-pound of nitrogen per 1,000 square feet per application.
St. Augustine growing in moderate to heavy shade should be fertilized in the spring and fall only, at a slightly increased rate of actual nitrogen, around 1½ pounds of nitrogen per 1,000 square feet. St. Augustine with more sunlight may need an additional application of nitrogen to enhance color during the summer. Iron sulfate can be applied to prevent iron chlorosis.
To Everything There Is a Season: Know Your Timing
In early spring there is often enough residual nitrogen to maintain grass through the first few mowings. If turf appears vigorous and healthy during these cuttings, delay the first fertilization until May. Again, in the absence of soil test analysis, apply a fertilizer with a 3-1-2 or 2-1-1 ratio at a rate equivalent to 1 pound of nitrogen per 1,000 square feet.
Fall fertilization promotes extended fall color and helps promote spring recovery of lawns. Fall fertilizers need only to contain nitrogen and potash. These nutrients will promote good leaf growth while promoting its cellular structure to withstand the winter cold temperature. Use a slow-release nitrogen source, with application rates not exceeding 2-pounds of nitrogen per 1,000 square feet.
Distribute the fertilizer using a broadcast drop-type spreader. Uniform distribution is essential to prevent light and dark streaks across the lawn. For better distribution, divide the fertilizer into two equal portions. Apply one portion lengthwise and the other crosswise over the lawn to ensure full coverage for a healthy, vibrant turf.
For more information about enhancing your landscape, or creating lasting natural outdoor spaces, please reach out to us at Woodlake Outdoor. Your project is our passion!