How High Should St Augustine Grass Be Cut?

What is St. Augustine Grass?

If you’re not already familiar with it, St. Augustine grass, sometimes also referred to as Charleston grass, is the coarse-textured space-covering grass most lawns in the United States grow.

It’s more prevalent in warmer regions like Florida because St. Augustine grass is weak in the fall, freezes, and starts turning brown. In fact, of all the warm season lawns, St. Augustine grass is probably the least suited for the cold.

It is the first choice for many lawn owners because it’s medium maintenance and pretty robust. Unlike other grasses, St. Augustine is actually not half-bad at protecting its food supply, so unless someone is getting their maintenance all wrong, you’ll never see this grass in any shade but green.

What Happens If You Cut St. Augustine Grass Too Short?

Cutting your grass at the correct height is crucial to a healthy lawn. This is because cutting too low can impede the nutrient supply of the grass.

Conversely, cutting the grass too high or infrequently will also put its integrity in harm’s way. This is because, and you can consider this a rule of thumb, you shouldn’t trim off more than 1/3rd of the blade’s length in one shot.

Doing so can prove hazardous for the grass since it disrupts the plant’s food supply and because fodder grass is a beacon, attracting insects and diseases.

The basic 4 tenets for immaculate lawn maintenance therefore are:

  • The height at which the grass is cut.
  • The frequency of mowing sessions (varies from season to season).
  • Water
  • Adding the correct pounds of nitrogen to your soil (based on your lawns square feet)

These 4 criteria are universal, and in case you’re wondering, apply to all forms of grass.

Follow the rules and tips in this guide religiously, and your lawn will make golf course owners jealous.

St Augustine Grass Mowing Height (by season)

Now, remember, St. Augustine is a seasonal grass, which means its upkeep needs to be slightly different each season. Producing a yearly maintenance calendar with monthly reminders is the best way to go about this.

Wondering how often St. Augustine grass needs to be mowed? Here’s an approximate mowing and upkeep schedule by season:

Spring & Summer

  • If it’s March, mow just a notch or shorter than you usually do to get rid of the dead material.
  • The best height to cut St Augustine grass during the summers is between 2.5 – 3.5 inches. If your lawn has shade falling over it, this needs to be between 3 to 3.5 inches.
  • Depending on how rainy your state gets during this time, your mowing frequency will vary. If it’s raining a lot, you’re going to see a lot of growth and maybe even some weeds, in which case you’ll need to mow more often. If not, still cut at least once a week, and if the environment’s too stressful, feel free to take off up to an extra inch.
  • You’re going to be facing some drought stress during this period. You will need to regularly monitor the lawn to assess its irrigation needs because this will vary from region to region.

If you’re in Florida ¾ to an inch of water should do the trick on dry, airy days. To figure out the intervals, you need to maintain between each irrigation cycle and check to see how many days it takes for the lawn to start showing signs of drought stress such as dryness or turning a blue shade.

Fall & Winters

  • From the start of fall, all the way to March-April, around the time summer begins, you will need to change your mowers settings to mow lower than usual. Make sure your mower is sharpened to be able to slice off the blades cleanly. Otherwise, they might develop infections or stunted growth.
  • The best height range to cut St. Augustine grass during the winter is between 2 – 2.5 inches.
  • It’s difficult to say how often you should mow your lawn in winters, but the idea is you want to keep your lawn height between 2-2.5 inches throughout this period. Depending on whether you get a rainy or dry winter, you’ll adjust your mowing frequency.

As soon as the temperature falls below 70 F, shave off another ½-1 inch of the lawn to help it acclimate to the changing weather.

  • Dry winter desiccations are a real problem. Some areas in the United States receive rainfall during this period, in which case you won’t need to irrigate that often depending on the square feet of your lawn.

But if you’re dealing with a dry rainless winter, it is best to keep irrigating the lawn yourself to eliminate turf loss. As a general rule of thumb, I’d say 3-4 weeks is a reasonable waiting period between each irrigation.

As stated before, please check the quality of your grass and soils moisture level first before deciding whether or not it needs to be watered.


Author: Matt Hagens

Hi, I’m Matt the owner of Obsessed Lawn. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Learn more about me and find me on Facebook.