Fertilizing Floratam Grass

Fertilizer Type

• A complete fertilizer with a 3-1-2 (or similar ratio, such as 15-5-10) is generally acceptable for fertilizing a "Floratam" lawn unless a soil test suggests otherwise. Each fertilizer is labeled with three numbers that indicate its percentage, by weight, of nitrogen, phosphorus and potassium, in that order. Nitrogen fertilizers are either slow-release (water-insoluble) or fast-release (water-soluble) types. Some products may contain a mixture of the two types of nitrogen.

Application Rate

• Never apply more than 1 pound of slow-release or 1/2 pound of quick-release nitrogen per 1,000 square feet of grass during a single application. Applying excessive fertilizer can burn the grass foliage or roots and encourage rapid growth that leads to an accumulation of thatch (living and dead stems, leaves and other debris on top of the soil), poor rooting and increased susceptibility to rots. To determine how much of a specific fertilizer is required to apply nitrogen at the rate of 1 pound of nitrogen per 1,000 square feet of lawn, divide 100 by the first number of the three numbers on the fertilizer label.

Timing Applications

• Make the first annual application of fertilizer to the "Floratam" lawn three weeks after the grass turns green, as long as no late frost is anticipated. Make additional applications every four to six weeks with fast-release nitrogen fertilizers or every six to eight weeks with slow-release nitrogen fertilizers when the grass is actively growing. Apply no more than a total of 4 to 6 pounds of nitrogen per 1,000 square feet of grass to the St. Augustinegrass lawn each year. Do not fertilize the St. Augustinegrass when it is not actively growing because of drought or dormancy, and avoid fall applications of nitrogen, which encourage a flush of growth prone to cold injury.

Additional Fertilizer Considerations

• The best way to determine the type and amount of fertilizer to apply to a "Floratam" lawn is to test the soil or grass leaf tissue (if the grass blades show problematic symptoms or you suspect a nutrient deficiency). Make sure fertilizer is broadcast evenly over the grass and water it in well to avoid burning the foliage. Leaving grass clippings on the lawn returns some nitrogen back to the soil. Grass growing in partially shaded sites generally requires less fertilizer and water than the same cultivar growing completely in the sun. Soil characteristics also influence nutrient availability to grass.