Soil pH

• Richard L. Duble with the Texas Cooperative Extension at Texas A&M University notes that St. Augustine grows satisfactorily in soils with a pH of 5.0 to 8.5, but its leaves may begin to yellow when soil alkalinity reaches 7.5 or higher. According to Iowa State University, organic mulch and wood chips can lower the pH of highly alkaline soils and make St. Augustine grass healthier.
  
  Make organic mulches at home from leaf mould, native shredded wood and compost. Create organic mulch for St. Augustine grass by letting the clippings remain on the ground when you mow. Make wood chips by running pruned branches through a wood chipper. The wood will need to be finely chipped so that it will settle among the grass's root system and release nutrients into the soil.
  
  

Soil Structure

• St. Augustine does not grow well in compacted soils. You can loosen soil and aerate it by sticking a garden fork several inches into the soil and working it back and forth. Alternatively, you can rent or buy a mechanical aerator that will do the work faster. Aeration also has the advantage of allowing more oxygen to reach the microorganisms living in the soil, thus improving soil health.
  
  

Moisture

• While St. Augustine needs moisture to grow, it does poorly in waterlogged soil. A simple drainage system requires that you dig a trench through the soggiest part of your lawn to a lower area, partially fill it with stones, re-cover it with dirt and replace the sod.
  
  

Mowing

• In "Texas Gardening the Natural Way," Howard Garrett notes that cutting away the leaf system causes grass to draw more heavily on carbohydrates stored in the roots to replace the cut leaves. To make St. Augustine grass healthier, let the root system retain carbohydrates longer for root and stem growth. Garrett recommends mowing at a 2-inch mower height when the lawn is 3 inches tall.
  
  

Disease

• St. Augustine is susceptible to fungal diseases, including brownpatch, gray leaf spot, rust and downy mildew. Prevent these diseases by providing adequate drainage and treat them by spraying the infected grasses with four teaspoons of baking soda mixed in one gallon of water.
  
  Choose varieties that are resistant to the St. Augustine Decline (SAD) virus, which causes grass to yellow and slowly die. If your lawn shows signs of SAD, plug your existing lawn with SAD resistant varieties on two- or three-foot centers. The healthy grass will outgrow the diseased grass in one to two years.
  
  

Fertilizer

• Spread organic compost over your lawn in early spring, early summer and in the fall, and add sugar to the compost to feed soil microorganisms. Use compost tea as a foliar spray to make St. Augustine grass healthier.