Mow your Palmetto St. Augustine between 1.5 and 2.5 inches tall.
Apply pre-emergent herbicide. This will cut down on summer weeds.
If you have had insect problems in the past, treat with broad-spectrum insecticide. If you use a granular variety, water the lawn immediately after application to help soil absorption. Make sure it has control for chinch bugs.
Don’t overwater. In the active growing season, Palmetto needs about one inch of water a week from natural rainfall or irrigation. Too much water can cause fungus.
Apply fungicide if needed. If you have had a fungus or disease in your Palmetto in the past or have quite a bit of shade in the yard, you should apply a systemic fungicide to prevent future outbreaks.