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.
Be sure to also check out our Homeowner Maintenance Guides for generic St. Augustine, Palmetto® St. Augustine and CitraBlue® St. Augustine.
Now let's get started with expert fall St. Augustine care tips!
Want us to do some fall lawn care for you?
If so, check out the Lawnifi Complete Program! The Lawnifi Complete Program is a year-round subscription for seasonal lawn care delivered to your door. Our boxes include everything your lawn needs in one lawn care subscription. Lawnifi is also introducing the Fall Complete Lawn Bundle to provide all the essentials your lawn needs for the fall season.
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- 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: Slightly Higher Than 2–2.5 inches
- CitraBlue St. Augustine: Slightly Higher Than 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.
2. Water Less as Temperatures Drop
In the fall, water your St. Augustine less as temperatures drop to prevent disease. St. Augustine typically needs about 1 inch of water weekly, including rainfall, but slightly less during the fall.
Changing temperatures and soil conditions, along with overwatering and shade from fall leaves, create optimal conditions for disease. Despite this, continue light watering to prevent drought stress and dehydration as the grass enters dormancy. Water in the early morning to reduce disease risk.
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.
Option 1: 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.
Option 2: 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.
4. Control Weeds with a Pre- or Post-Emergent Herbicide
As temperatures cool, you can safely apply both post-emergent and pre-emergent herbicides to your St. Augustine lawn. Summer weeds may die off, but winter weeds will soon emerge. Apply a pre-emergent herbicide in the fall to prevent them.
Pre-emergent herbicides prevent new weeds, while post-emergent herbicides control existing ones. Fall is the best time for pre-emergent application, especially if winter weeds have been a problem before. You can also apply it in spring around March or April.
Read product labels before application.
5. Keep an Eye Out for Insect Infestations
Applying a preventative insecticide is more effective and likely cheaper than dealing with an infestation. Use a broad-spectrum insecticide to protect your St. Augustine lawn from pests.
Key insects to watch for include chinch bugs, grub worms, sod webworms, fall armyworms and mole crickets. Treat any activity with an appropriate insecticide, and always read product labels thoroughly. For granular insecticides, water the lawn immediately after application for better absorption.
Visit our Insect Identification blog for more details.
Read product labels before application.
6. Prevent Disease Outbreaks as Temperatures Change
Apply a systemic fungicide at preventative rates around early fall to help your grass stay healthy and prevent disease outbreaks. If you've had past issues, multiple applications may be needed, especially at higher rates for spring problems.
For granular fungicides, water the lawn immediately after application to aid absorption. Always read product labels thoroughly before use.
Common diseases include gray leaf spot, large patch, Cercospora leaf spot, leaf rust, and Bipolaris leaf spots. In South Florida, SCMV-infected Floratam St. Augustine can develop lethal viral necrosis from fall through spring.
Tip: Remove dead leaves. Accumulated leaves create shaded, moist spots that damage the grass. Rake weekly to prevent this damage.
Azoxy 2SC Select
Read product labels before application.
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.
