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How to Treat St Augustine Grass

By Kelly Shetsky ; Updated September 21, 2017
Fertilize and mow St. Augustine grass to make it look its best.
grass, image by Greg Pickens from Fotolia.com

St. Augustine grass is commonly found in humid, warm areas such as the Gulf of Mexico, Mediterranean and southern parts of the United States. The plant handles salt and shade well, and is conducive to many soil types. St. Augustine grass has a blue-green color which gets darker as you treat the grass with fertilizer and water.

Purchase a fertilizer that is high in nitrogen. Nitrogen enhances leaves and foliage, bringing out the green color of St. Augustine grass. Nitrogen is the first element listed on the package, followed by phosphorus and potassium. Look for fertilizer with nitrogen in a slow-release form, because it will feed the grass on a continual basis.

Treat St. Augustine grass with fertilizer as the grass turns green at the beginning of spring. Spread the food two to six times through the end of fall. If using slow-release fertilizer, it will take fewer applications than will water-soluble products. Follow the application instructions provided by the manufacturer. Applying fertilizer too early or too late in the season can cause damage to St. Augustine grass.

Spread one-half pound of nitrogen per 1,000 square feet of ground. Slow-release food requires 1 pound per 1,000 square feet.

Set a sprinkler up if you notice St. Augustine grass is wilting. Give it an extra 1/2 to 3/4 inches of water. There's no need to water again unless it wilts. Rain water is usually sufficient.

Cut St. Augustine grass so that it is 3.5- to 4-inches tall. Mowing it shorter than that can cause pest issues, shallow root growth and stress.

Use an herbicide formulated for St. Augustine grass to eliminate weeds. If you have crabgrass from last season, use a pre-emergence herbicide. Apply it during the late winter or early spring, before growth starts. Control grassy weeds with a post-emergence herbicide applied in the early summer.


Things You Will Need

  • Fertilizer
  • Mower
  • Water
  • Herbicides


  • Gray spots or brown patches indicate the use of too much nitrogen fertilizer or too much water. Cut back on both if you notice this problem.


  • Do not mow more than one-third of a leaf blade at any one time.

About the Author


Based in New York State, Kelly Shetsky started writing in 1999. She is a broadcast journalist-turned Director of Marketing and Public Relations and has experience researching, writing, producing and reporting. She writes for several websites, specializing in gardening, medical, health and fitness, entertainment and travel. Shetsky has a Bachelor of Arts in communications from Marist College.