What Is the Best Fertilizer to Put on St. Augustine Grass?

Lawns of St. Augustine grass can be found throughout the southern United States, from the Carolinas to Texas. It is an especially hardy variety well suited to the hot, humidity summers of the South. Yet to look its best, St. Augustine grass requires regular applications of fertilizers.

Established Lawns

A commercial, fast-releasing nitrogen fertilizer, available at your local garden supply center, is best for St. Augustine grass. Nitrogen will ensure that the St. Augustine grass grows at a steady rate and has a healthy lush green color. Using your lawn spreader, apply 1 pound of fertilizer per 1,000 feet of lawn.

New Lawns

Once a month for the first three months after you have planted your St. Augustine grass lawn, apply a starter fertilizer that has a high phosphorus content. You can also use a balanced complete lawn fertilizer. To prevent weeds from growing with the St. Augustine grass, use atrazine. If weeds have already appeared in the lawn, apply asulam, also known as Asulox.


Begin fertilizing your lawn in early spring, when the St. Augustine grass is still brownish yellow. Once every 30 to 60 days apply another pound of nitrogen per 1,00 feet to your lawn. Keep up this regimen through late fall. With regular feeding, your St. Augustine lawn will remain green into the first weeks of winter.

Supplementary Fertilizers

If Bermuda grass and weeds invade your lawn, or if patches of St. Augustine grass are dying, there is probably an iron deficiency in the soil. You can correct the problem by treating your lawn with iron sulfate or iron chelate. Once a year spread potassium on your lawn at a rate of half a pound per 1,000 feet. Potassium encourages the growth of sturdy roots and boosts the St. Augustine grass' resistance to cold and drought.


Chinch bugs and other harmful insects are attracted to the thick thatch of St. Augustine grass. To reduce the chance of infestation, thatch your lawn every autumn. If your lawn is already infested, consult a lawn care professional about the most effective insecticide. It will take between two and six applications of insecticide to clear your lawn of chinch bugs, slugs, and other pests.