Best Fertilizer for St. Augustine Grass
What is the best fertilizer for St. Augustine grass? Why do you need to be concerned with finding the right one? St. Augustine grass is one of the most popular lawn grasses in southern, coastal areas of the United States. As lawn grass types go, St. Augustine is slightly more labor intensive than turf species. One important aspect of St. Augustine maintenance is following the right fertilizer schedule.
Amount of FertilizerSt. Augustine is a heavy feeder. It needs at least one pound of nitrogen per 1,000 square feet, per month to stay evenly green. Less than that, and you get irregular growth and coloring. More than that, and your lawn will produce very lush growth that is open to pest and disease problems.
pH and Nutrient UptakeOne problem that St. Augustine Grass can have is iron chlorosis, or lack of iron. This most frequently occurs in alkaline soils (pH of above 7.0). The optimum pH range for St. Augustine is 5.5 to 7.2. The pH of the soil affects nutrient uptake, not just for iron, but for a wide range of macro and micro nutrients in the soil. With St. Augustine, if you are having growth or color problems, try testing the pH before adding anything to the soil. If the pH of the soil is too high, you can add sulfur to the soil. Lawn and garden centers will have products specifically for lawn care. If you have corrected the pH and the grass blades are not dry, but are a yellow color, that is a sign that you need to use a foliar iron spray on the grass. (Foliar means it sticks to and is absorbed through the plant leaves.)
Type of FertilizerThe nutrient most needed by St. Augustine Grass is nitrogen. The amount of nitrogen in fertilizer is indicated by the first number in the fertilizer analysis on the bag or container of fertilizer. For example a 10-5-5 fertilizer is 10% nitrogen active ingredient. Nitrogen is mobile in the soil, so a soil test will not tell you if you need to add nitrogen. However, phosphorous and potassium, the second two macro-nutrients contained in most fertilizers are less mobile. A soil test can tell you if your soil is lacking in those. If you have plenty of soil phosphorous and potassium in your soil, apply a 10-0-0 or a 20-0-0 fertilizer. In other words, a nitrogen-only fertilizer.
When to Apply FertilizerFertilizer applied at a time when the grass is not actively growing is fertilizer down the drain, literally. Apply fertilizer once the grass starts to green up in the spring, continuing on into the early fall. Do not fertilize in the months of November-April. The grass will be dormant during this time, and the fertilizer will leach out of the soil and into the groundwater. Additionally, during times of extreme heat in the mid-summer, if the grass turns dry and brown, it is also dormant and water stressed--not a good time for fertilizer. St. Augustine is a tough grass that is heat, cold and drought tolerant if properly cared for. Using the best fertilizer for St. Augustine grass will go a long way toward keeping this grass healthy.