"Floratam" St. Augustinegrass (Stenotaphrum secundatum “Floratam”), of tropical origin, is grown widely as lawns along coastal areas with warm climates. St. Augustinegrass turns green in the spring and remains green throughout the summer, going dormant in the winter when it tends to turn tan or brown. Its fertilizer requirements are not substantially different from those of other cultivars of St. Augustinegrass. "Floratam" can be grown in U.S. Department of Agriculture Plant Hardiness zones 8 through 10.
The numbers on fertilizer packages show the ratio by weight of nitrogen (N), phosphorus (P) and potassium (K). Water soluble fertilizer with ratios of 3-1-2 or 4-1-2 of N, P and K are best for St. Augustinegrass. A 3-1-2 fertilizer has a ratio of 3 parts of N to 1 part P and 2 parts of K. Fertilizers with numbers of 21-7-14 or 15-5-10 are examples of fertilizers with a 3-1-2 ratio of N, P and K.
Calculating Actual Nitrogen
Nitrogen application rates typically are listed in the amount in pounds per 1,000 square feet. Actual nitrogen is calculated by dividing 100 by the percentage of nitrogen listed on the package. Dividing 100 by 27 gives the amount of 27-7-14 fertilizer needed to supply 1 pound of nitrogen The result is 3.7, meaning that roughly 3 3/4 pounds of 27-7-14 fertilizer will supply 1 pound of actual nitrogen.
Water soluble fertilizer comes in the form of dry granules that must be scattered on the grass and then watered into the soil with irrigation. More expensive slow-release nitrogen does not dissolve readily in water and releases the nitrogen into the grass over a longer period of time. There are no standard application amounts or application rates for slow-release fertilizers. These typically are listed on the brand.
A rich green lawn that can sustain heavy use requires 1 pound of actual nitrogen per 1,000 square feet of lawn applied monthly for three months beginning when the grass turns green in the spring. A soluble 3-1-2 or 4-1-2 fertilizer is best. An additional application of 1 pound of potassium per 1,000 square feet of lawn is needed in late summer or early fall before the grass loses its color. Applying 1 pound of nitrogen per 1,000 square feet every 30 to 60 days through late fall will help "Floratam" remain green through the winter.
Low Maintenance Lawn
A lawn with modest traffic and minimal upkeep requires 1/2 pound of actual nitrogen per 1,000 square feet applied in late spring after the grass turns green and again one month later. A soluble 3-1-2 or 4-1-2 fertilizer is best. In late summer or early fall, an additional application containing 1 pound of potassium per 1,000 square feet of lawn is needed.
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