Nutrition & Growth of St. Augustine Grass

Propagation and Initial Growth

• St. Augustine grass commonly propagates from either sod plugs or seed. Growers may position standard 2-inch sod plugs at 1-foot intervals in the soil, or they may distribute the seed at a density of approximately half a pound of seed for every thousand square feet of soil, according to Texas A&M University. At this stage the new grass requires several weeks of moist soil and a generous dose of fertilizer before it can take root and start to thrive with less attention. The first application of fertilizer should contain a full complement of standard plant nutrients.

Supplemental Nitrogen

• St. Augustine grass requires generous amounts of nitrogen, the level of which depends on the kind of nitrogen-based fertilizer you use. Consult the labeling on the fertilizer to see whether nitrogen is the primary ingredient and what balance of fast- and slow-release nitrogen it contains. Hancock Seed Co. recommends growers use half a pound of quick-release nitrogen fertilizer or 1 pound of slow-release fertilizer for every thousand square feet of grass.

Other Nutrients

• In addition to nitrogen, St. Augustine grass may require nutritional support with other elements. Soil with an alkaline pH, for instance, can cause the grass to develop symptoms of iron deficiency. Texas A&M recommends growers add an iron-based fertilizer such as iron chelate or iron sulfate to compensate for this problem. St. Augustine grass also needs potassium and phosphorus. Growers can supplement with potassium by giving the grass about half as much if it, by weight, as the nitrogen they have administered. Phosphorus levels rarely require supplementation.

Ongoing Growth Considerations

• Other factors that influence the growth of St. Augustine grass include climate, pests and potential for disease. This variety of grass needs light to moderate shade, at most, to achieve optimal growth and thickness, and it prefers mild to hot temperatures, coastal moisture levels and good soil drainage. Chinch bugs, white grubs, cutworms, ground pearls and other insects can harm St. Augustine grass, and growers must stand ready to employ insecticides to deter these pests. In most cases fungicides can deal with common disease threats such as gray leaf spot, downy mildew and brown patch.