When Does St. Augustine Grass Go Dormant?

St. Augustine grass thrives in most soils, shaded areas, and in hot climates by the seaside. Being one of the tolerant grass species, St. Augustine’s blue and green blades create a dense turf that spreads easily and quickly. However, some instances can make a St. Augustine lawn go dormant.

St. Augustine grass goes dormant when temperatures drop to 12 degrees Celsius or 55 degrees Fahrenheit. The grass ceases to grow, and its leaves begin to turn brown, showing that the grass has gone dormant.

Read on to learn more about how you can know if St. Augustine grass is dormant, tips to prepare the lawn for winter, and how to treat dormant St. Augustine grass. 

How Do You Know if St. Augustine Grass is Dormant or Dead?

Sometimes dead and dormant grass looks the same, and you can’t tell the difference by merely observing the leaves or color. 

Dormancy means a time when the grass is not in an active growth period. For example, warm-season grass like St. Augustine may go into a dormant phase during the cold season, but it will grow back with the right watering and warm weather. Having dormant grass means the grass adopts a natural protection mechanism that protects it from dying by preserving the grass’s energy.  

One way to know if St. Augustine grass is dead is to grab some of it and shake it off. If the grass pulls out without any resistance, it shows that the grass is done; if you also notice some brown and green patches on the grass, that’s an indication that the grass will never come back to life. 

The grass’s blades start to decay when dead and the grass will stay brown when soil temperatures are below 12 degrees celsius. 

However, dormant grass resists when you try to pull the blades from the ground. The grass also feels dry when you touch it and you’ll notice that all the grass in the yard turns brown uniformly. You won’t notice patches on the grass. 

The other way to tell if you have dead or dormant grass is to wait until the temperatures go back to normal. Grass that is dormant will spring back in the spring, but dead grass will remain the same even with warmer temperatures. 

Does St Augustine grass go dormant in winter?

St. Augustine grass goes dormant during winter when the temperatures dip below 12 degrees Celsius or 5 degrees Fahrenheit. During this period, the grass turns brown. However, in tropical or coastal areas, the grass will retain its color throughout the year. 

If you notice that the grass has gone dormant after the temperature drop, you’ll have to wait until the temperatures go above 12 degrees celsius. It’s recommended to care for the grass during the dormancy period to ensure you get back a healthy lawn. 

Note that the dormancy period can last for months or weeks, but this is dependent on the temperatures and care provided. 

How Do You Prepare St. Augustine Grass for Winter?

Although St. Augustine grass can go dormant during the cold season, there are certain steps you can take to prepare the grass for winter.  

Here are some things you can do to prepare St, Augustine grass for winter before it becomes dormant.

  • Fertilize throughout the Year

Fertilizing your lawn year-round provides it with the needed food and nutrients to survive even when it goes dormant. You can do this by applying a fertilizer every 3 months or once a month when using a slow-release fertilizer.

Remember to apply a winter fertilizer a month before the season arrives and two months later in the middle of the winter. These fertilizers have fewer nutrients for growth, but they help preserve the grass’s health and green color. Slow-release fertilizers only need to be applied before winter and when the spring season starts. 

Fertilization lessens the impact winter has on lawns. 

  • Reduce Mowing

You need to reduce mowing during the fall and winter. Focus on mowing once every two months. Also, ensure that you raise the height of the mower blades as leaving it a bit long helps to preserve energy to ensure it stays healthy through the cold season. Cut no more than ⅓ of the grass. 

Skipping on the mowing during this season allows the grass to retain its growth and reduce any wear and tear. 

  • Avoid Watering During this Season

Reduce the frequency of watering when the cold season approaches. You may not need water during this season as some areas experience a rainy season coupled with cool temperatures. Watering can be done when it doesn’t rain for some time or when the weather gets warm. 

  • Don’t Forget Weed Control

Some people ignore weed control when the cold season approaches. However, this is the best time to handle it by applying preemergent herbicides when the soil temperatures dip and use a postemergent herbicide when required. 

Note that St. Augustine grass is sensitive to some herbicides and you need to choose a proper product to avoid destroying the turf. 

  • Give it Time

It’s natural for St. Augustine grass to go into a semi-dormant period when the temperatures drop. Don’t be in a rush to push the turf out of this period with too much nitrogen. Using nitrogen on your grass will help it retain the green color, but later destroys it. Wait for the season to end and you can have your healthy, green lawn back. 

How to Treat Dormant St. Augustine Grass

You can revive dormant St. Augustine grass to its former glory, but you need to take certain steps. These include:

  • Water the Grass

It’s vital to water St. Augustine after the grass changes its color and if the temperatures rise over 40 degrees Fahrenheit. Avoid watering when the temperatures go below 40 degrees as this could form ice that will kill your dormant grass. 

  • Use Proper Mowing Techniques 

Most people make the mistake of using dull mower blades or mow too close to the grass, something that can kill the grass. However, when mowing, ensure that you never mow more than ⅓ of the blade’s length. Avoid mowing a wet lawn.

You can go back to your mowing routine after the dormancy period. 

  • Avoid Overfertilization

Unfortunately, fertilizers only burn your lawn and make the grass appear brown like it is dead. To treat this problem, you’ll need water to neutralize the excess nitrogen content that could be burning the grass. Soak any area that’s turned brown with water daily for a week with at least an inch of water.

Using a sprinkler promotes uniform growth. Do not overwater the grass as it could lead to poor growth, change the grass’s color, and cause fungal infections.

Should You Water Dormant St. Augustine Grass?

St. Augustine grass goes through a dormancy period during the fall and winter months. Watering the lawn during this phase prevents excessive dehydration.  Dry winters can lead to winter desiccation and pose drought stress. Watering the lawn prevents this problem and reduces turf loss during the cold season. 

If your area receives ample rainfall during winter, you can reduce the watering frequency. However, if no rain occurs within three weeks, you’ll need to water the grass to prevent death. Your focus during this period is to keep the grass free from color changes, wilting, and drought conditions. 

Should You Mow or Cut Dormant St. Augustine Grass?

You should not mow dormant lawns. Using a mower at this time only bruises the blades and ends up damaging your turf.

Remember that when the grass is dormant, it’s not growing. That means cutting the grass exposes the fresh blades to harsh winter conditions, and the wounds won’t recover until spring. Moreover, mowing can lead to fungus infections and winter disease. 

Mowing your lawn before the dormancy period keeps the grass looking neat, and you may not need to trim it again until it’s warm again. 

Can You Add Fertilizer to Dormant St. Augustine Grass?

St. Augustine grass goes dormant during winter, and while in this state, it doesn’t need watering or fertilizer application as it’s not actively growing.

It’s recommended to retain a fertilizing schedule until four weeks before the first frost. You need to stop fertilizing the lawn until about three weeks after the grass turns green. You can use nitrogen fertilizer, and complement it with a potassium fertilizer in the fall. 

Can You Prevent St. Augustine from Going Dormant?

Unfortunately, there’s nothing you can do to prevent St. Augustine grass from going dormant, especially in areas where the grass gets into dormancy when the temperatures drop. 

St. Augustine grass stays green during the other months, but it goes dormant and turns brown when temperatures are below 55 degrees Fahrenheit. Adding fertilizer and continuously watering your lawn won’t prevent the grass from going dormant. 

The best thing about St. Augustine grass is that it goes back to its former glory with careful mowing,  watering, and adding fertilizer to the soil. 

You can have your lawn remain green throughout the year by planting a mixture of grass seeds. That means having a warm-season and cool-season variety. The cool-season grass will ensure your lawn stays green when St.Augustine goes into dormancy.


St. Augustine grass does well as a warm-season turf but goes into dormancy when the temperatures drop below 55 degrees Fahrenheit. Learning how to care for your lawn using the above methods during this cold season will help you revive your grass. 

Also read

Does St Augustine Grass Grow In Shade?

Will St. Augustine Take Over Bermuda Grass?

Can you Dethatch St. Augustine grass?

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