St. Augustine grass goes dormant when soil temperatures dip down to 55℉ (12℃). As a warm-season grass, suitable for hot, humid climates, St. Augustine grass goes dormant during cold temperatures. Dormancy conserves the grass’s energy and prevents damage due to freezing temperatures. During dormancy, St. Augustine has reduced water needs and does not require fertilizer.
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How Do You Know if St. Augustine Grass is Dormant or Dead?
St. Augustine grass goes dormant in cold weather, but it can be difficult to tell dormant St. Augustine from dead St. Augustine. Here are the signs of dormant grass vs. dead grass, so you’ll know whether or not your St. Augustine will green up again in spring.
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St. Augustine Dormant Months by Region
Because St. Augustine enters dormancy based on soil temperature, the dormant period is different based on the region where the grass is planted. In the United States, St. Augustine is typically found from South Carolina through Central Texas. St. Augustine is not cold- or drought-resistant, so it is not planted in northern regions or dry areas.
St. Augustine Dormant Months by State
- South Carolina: Mid-November–Mid-March
- Georgia: Mid-November–Mid-March
- Florida: No dormancy
- Alabama: Mid-November–Mid-March
- Mississippi: Mid-November–Mid-March
- Louisiana: December–February
- East Texas: Mid-November–February
- Southern California: No dormancy
Does St Augustine Grass Go Dormant in Winter?
St. Augustine grass will go dormant during winter if soil temperatures go down to 55℉ (12℃) and lower. During dormancy, St. Augustine grass will cease growing almost completely and aboveground growth will turn brown. In very warm regions, such as South Florida, St. Augustine grass may remain green all year round, never entering dormancy.
If your St. Augustine does go dormant, dormancy will continue until temperatures rise above 55℉ (12℃). Dormancy can last weeks or months, depending on the local climate. If watered and cared for during dormancy, St. Augustine will return to brilliant green life once dormancy ends.
How Do You Prepare St. Augustine Grass for Winter?
In order to care for your St. Augustine grass just prior to dormancy and emerges from winter beautiful, lush, and vibrant green, take the following steps when the weather begins to cool in fall, before your St. Augustine has gone dormant:
- Perform a soil test to determine soil pH. St. Augustine thrives when soil pH is 6–6.5. If the pH is below 6, apply lime to reduce soil acidity. If the pH is above 6.5, apply sulfur to increase soil acidity.
- Avoid using nitrogen fertilizers in the fall, as they will be less effective at this time of year. Consider an application of potash or similar potassium fertilizer.
- Mow St. Augustine to a blade height of 2–2.5 inches as it approaches dormancy. This is an ideal winter height that promotes spring green-up.
- Continue to water your St. Augustine even as growth slows in cooling temperatures. St. Augustine’s growth slows to a crawl as temperatures approach 60℉, but it still requires regular watering.
How to Treat Dormant St. Augustine Grass
Dormant St. Augustine still requires care and maintenance to maintain lawn health and promote a robust spring green-up. Dormant grass isn’t dead grass, so it can’t just be forgotten when it turns brown in cold weather. Here’s how to care for dormant St. Augustine grass.
- Even after the blades turn brown, water St. Augustine. As long as temperatures remain above 40℉, water St. Augustine with 1 inch of water (typically an hour with sprinklers) once every 2 weeks. Subtract any precipitation from the lawn’s watering needs.
- If temperatures are below 40℉, do not water your St. Augustine. Watering in these conditions can contribute to ice formation that will harm your grass.
- Do not mow dormant St. Augustine grass. St. Augustine will not grow while dormant and mowing can put stress on the grass since it can’t recover from being cut.
Should You Water Dormant St. Augustine Grass?
Dormant St. Augustine grass still requires water. Although the visible part of the grass is not growing, the roots beneath the surface are still very much alive, growing and building energy for spring. If you experience a dry winter and don’t water your St. Augustine, the grass may die.
Due to reduced growth and the fact that lower temperatures result in less water evaporation, St. Augustine requires less water during the winter. About 1 inch of water once every 2 weeks should be sufficient. Most sprinkler systems deliver about 1 inch of water in 1 hour.
In many regions, winter precipitation will deliver all the water your St. Augustine needs. Monitor winter rainfall and subtract it from your lawn’s watering needs.
Should You Mow or Cut Dormant St. Augustine Grass?
Not only is there no need to mow dormant St. Augustine grass, but it can also be harmful to the grass. Dormant St. Augustine is not actively growing, so as long as you perform a final mowing run before dormancy, your lawn should look neat all winter.
The danger in mowing dormant St. Augustine grass lies in the fact that the grass isn’t growing. Think of the top of freshly cut grass blades as open wounds. During the growing season, grass can recover quickly and heal these wounds, but during dormancy, these cuts won’t heal. Mowing dormant St. Augustine can invite winter disease and fungus.
Can You Add Fertilizer to Dormant St. Augustine Grass?
There is no need to fertilize dormant St. Augustine grass. According to Texas A&M University, you should not fertilize St. Augustine from December through February, except in cases where you are overseeding your St. Augustine with cool weather grass.
Ideally, you should fertilize your St. Augustine after spring green-up with a slow-release high-nitrogen fertilizer. Then, fertilize in fall with a low-nitrogen, potassium fertilizer, ceasing all fertilization 4–6 weeks before the first average frost. By adhering to this schedule, you will get the most out of your fertilizer and your grass. Time and money spent fertilizing dormant St. Augustine will yield minimal results.
Can You Prevent St. Augustine from Going Dormant?
No amount of fertilizer or soil treatment will prevent St. Augustine from going dormant when soil temperatures reach 55℉ (12℃). St. Augustine is triggered to enter dormancy by temperature alone. However, you can keep your lawn green all year long in temperate regions by overseeding your St. Augustine with a cool-weather grass, such as fescue, in fall.
Fescue and some other cool-season grasses will remain green even as temperatures dip to 40–45℉ (4–7℃). In many regions of the southern United States, this will keep fescue green all winter long. To overseed with fescue, cast the seed 3 weeks before the first expected frost. The fescue will transform your lawn into a green oasis just as your St. Augustine enters dormancy. This is the best way to cheat nature and keep a green lawn all year round even if your St. Augustine goes dormant.