Fall Care Tips for Your St. Augustine Lawn

With the changing of the seasons also comes the changing of temperatures, weather and soil conditions. It’s important that you change your St. Augustine maintenance around during the different seasons because the grass and environment will have different demands. Check out our list of tips, guides and videos below.

Be sure to also check out our Homeowner Maintenance Guides for generic St. Augustine, Palmetto® St. Augustine and CitraBlue® St. Augustine. If you’re looking for maintenance tips on a different type of grass, take a look at our Fall Lawn Maintenance Tips article.

Now let’s get started with expert fall St. Augustine care tips!

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Jump to…

• 1. Reduce Mowing for Deeper Roots
• 2. Water Less as Temperatures Drop
• 3. Fertilize Your Lawn with the Right Nutrients
• 4. Control Weeds with Pre- or Post-Emergent Herbicide
• 5. Keep an Eye Out for Insect Invasions
• 6. Prevent Disease Outbreaks as Temperatures Change

1. Reduce Mowing for Deeper Roots

When it comes to mowing your St. Augustine, a typical height is about 2–4 inches. This can alter for different cultivars of St. Augustine though. Palmetto St. Augustine, for example, performs best in the fall at a height of about 2–2.5 inches while CitraBlue performs best at a height of 2–3 inches.

However, during the fall, you should maintain a height that’s slightly higher than that of the summer. This encourages deeper root growth so that your grass survives during winter dormancy when temperatures get cooler. The roots are what keeps the grass alive underground while the blades above ground endure harsh temperatures.

• Palmetto St. Augustine: Slightly Higher Than 2–2.5 inches
• CitraBlue St. Augustine: Slightly Higher Than 2–3 inches

For more information on mowing heights, visit our Lawn Mowing Guide.

2. Water Less as Temperatures Drop

In the fall, you’ll want to water your St. Augustine less as temperatures begin to drop as too much water can lead to disease.

Your St. Augustine generally only needs about 1-inch of water weekly including rainfall. Water slightly less during the fall. Temperatures are changing around this time of year and so are soil conditions.

Fall is one of the most optimum times of the year for disease to start appearing—especially when overwatering and shade from fall leaves combine. Disease can be caused by a number of things, but it’s usually caused by overwatering, changing temperatures and shade.

Regardless of disease outbreaks, you’ll still want to water your lawn to prevent drought stress while the grass is actively growing. Even though your St. Augustine will begin to enter stages of dormancy towards the end of the fall season, light watering will prevent dehydration. Watering your St. Augustine in the early morning will decrease the risk of certain turfgrass disease. For more information on watering, visit our Lawn Irrigation Guide.

3. Fertilize Your Lawn with the Right Nutrients

Fertilization differs this time of the year compared to the other active growing seasons (spring and summer). As previously stated, outdoor temperatures are starting to change—so are soil conditions. Your grass is a living thing that needs specific nutrients at this time. Depending on the area you live in, your St. Augustine will likely enter a state of dormancy.

What is the best fertilizer for St. Augustine grass in the fall?

Sod University recommends two different fertilizer options for the fall; however, you will only need to use one of the two options for fall fertilization. The Fall Fertilizer Box, in particular, has three separate bottles of liquid fertilizer in it that help your lawn recover from the hot summer temperatures it just endured as well as prepare for the colder temperatures ahead.

When to Fertilize St. Augustine Grass in the Fall

Step 1: In the early fall, start off with applying Boost to revitalize the green leaf blade color after the heat of summer. The summer heat can really stress your grass out and may even leave hot spots or drought damage. With Boost’s time-release formula, the rapid green-up of your lawn will last from the time of application through the remainder of the growing season.

Step 2: In the mid-fall, you should make an application of the second bottle in the box, Maintain, for well-balanced nutrition. Maintain serves to help with color retention late into the cooler months ahead and fortifies the root system to help it survive throughout dormancy or snow.

Step 3: In the late fall, you should apply Recover to prepare your lawn for environmental stressors of this colder weather. You can read more about The Fall Fertilizer Box and it’s mixture of nutrients in a separate Sod University blog here.

Lawnifi Foundation is a slow-release granular fertilizer option that comes in a 25-pound bag and lasts for three months. With a 29-0-5 NPK formulation, Lawnifi Foundation is the perfect granular fertilizer for lawns and gardens. The two percent iron included in Lawnifi Foundation’s mixture helps plants carry oxygen throughout the leaves, roots and other parts of the plants to promote a green, healthy lawn.

Featuring slow-release nitrogen, Foundation gradually feeds your lawn over an extended period of time without overwhelming your lawn with nitrogen during the fall. Both Lawnifi Foundation and the Fall Fertilizer Box cover 5,000 sq. ft. Learn more in Granular vs. Liquid Fertilizers or by clicking on the two products below. For more generic information about the Lawnifi brand, read Why Use Lawnifi Fertilizer?.

4. Control Weeds with a Pre- or Post-Emergent Herbicide

Your St. Augustine lawn has just made it through the summer months when herbicide applications damage grass due to hot temperatures. Now that it’s starting to cool down, you are free to apply both post-emergent and pre-emergent herbicides without risking any damage to your lawn if applied properly.

You may even notice that the weeds from summertime are starting to die off. Unfortunately, there are winter weeds that will start to pop up when the months are colder too. We recommend applying a pre-emergent during the fall to prevent winter weeds.

There’s a difference between pre- and post-emergent herbicide control for weeds. A post-emergent herbicide controls any current weeds you are experiencing whereas a pre-emergent herbicide, as its name suggests, serves to prevent weeds from appearing.

Some hard to control weeds that may appear around this time include Poa annua, purple deadnettle, chickweed or henbit.

Fall is actually the best time to apply a pre-emergent—especially if winter weeds have been a big problem in the past years. You can also do this in the springtime around March or April. Check out some of our recommended pre-emergent products below and be sure to read labels thoroughly before application. 

Read more about pre-emergent applications in the fall in How to Use a Pre-Emergent Herbicide in the Fall and learn about the various types of weeds in Identifying Common Lawn Weeds.

Read product labels before application.

5. Keep an Eye Out for Insect Infestations

It’s better to apply an insecticide as a preventative as opposed to having to resolve an infestation once damage has already occurred—it’s probably less expensive too. Apply a broad-spectrum insecticide to prevent any harmful insects from taking over your St. Augustine.

Although there could be a variety of insects that may be invading your lawn at this time, the main ones most universities recommend you look out for in your St. Augustine are chinch bugs and grub worms. 

Sod webworms, fall armyworms and mole crickets can also be a problem in St. Augustine lawns at this time. If you have insect activity, treat with an insecticide labeled to treat the insect you are seeing. Be sure to read product labels thoroughly before application. If you use a granular variety, water the lawn immediately after application to help with absorption. Visit our Insect Identification blog for more details.

Read product labels before application.

6. Prevent Disease Outbreaks as Temperatures Change

We recommend applying a systemic fungicide at preventative rates around the beginning of the fall season or right beforehand. This helps the grass enter colder months in a healthier condition by keeping disease outbreaks at bay.

If you’ve had a problem with lawn disease around this time before, you may need to make multiple applications of the systemic fungicide in affected areas. If disease outbreaks were a problem during the spring, apply a fungicide at higher rates to the problem area(s).

If you use a granular variety, water the lawn immediately after application to help soil absorption. Above all, read product label instructions thoroughly before application for detailed instructions. 

A few common diseases that may be found include large patch, Cercospora leaf spot, leaf rust and Bipolaris leaf spots. If you live in South Florida, SCMV infected Floratam St. Augustine tends to develop lethal viral necrosis fall through spring.

Tip: Remove any dead leaves.

As dead leaves accumulate on the ground during the fall, they create shady, darker spots on the lawn. Light cannot reach these areas and moisture becomes trapped. This quickly damages the grass underneath these spots.

When warm season grass goes dormant, it can be difficult to notice any discoloration after the leaves are removed. Come springtime, you will notice the damaged areas while the rest of the grass turns green again. Depending on how many trees are nearby, consider raking once a week. Learn more here.

Read product labels before application.

Pictured above: An image of large patch.

Lastly, lawn patch work and light topdressing with a sand and topsoil mix is a great way to recover any weak areas in your lawn that were caused by the summer heat. If you notice any hot spots, apply a light layer of topdressing to help it recover.

You can also check out our individual Homeowner Maintenance Guides for generic St. Augustine, Palmetto St. Augustine or CitraBlue St. Augustine.

And remember…if you want lawn care made simple, the Lawnifi Complete Subscription provides your lawn with what it needs during the current season and for years to come.