If you have a warm season lawn (think Bermuda, Zoysia, Centipede, or St. Augustine grass), fall looks a little different than it does for cool season lawns. (Not sure about your grass type? Check out our guide here. If you live in a South or Transition zone, chances are you have warm season grass.) While cool season homeowners are busy overseeding, your focus should be on stopping weeds before they take hold.
Why Fall Weed Control Works
Fall weed control is especially important because weeds and turf behave differently as temperatures cool.
Perennial broadleaf weeds such as dandelion, clover, and plantain begin shifting energy below ground in fall, storing carbohydrates in their roots and crowns. That makes fall a useful time to spot-treat weeds that are already visible, while pre-emergent treatments help prevent winter annual weeds from establishing in the first place.
For warm-season lawns, that means using two different strategies:
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Pre-emergent weed control helps stop winter annual weeds such as annual bluegrass, chickweed, and henbit before they establish.
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Post-emergent weed control targets broadleaf weeds that are already actively growing in the lawn.
The key is matching the treatment to the type of weed you are trying to control.
What Weeds Does Fall Pre-Emergent Help Prevent?
Fall pre-emergent is primarily used to target winter annual weeds that germinate as soil temperatures cool.
Common targets include:
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Annual bluegrass (Poa annua)
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Chickweed
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Henbit
These weeds can begin establishing in fall, survive through the cooler months, and become much more noticeable by late winter or spring. Applying pre-emergent at the right time helps reduce how many of these weeds successfully establish in your lawn.
Here’s your simple, step-by-step guide to fall lawn care for warm season grasses.
Mow and Clean Up
As temperatures cool and your grass growth slows, keep mowing at your regular height until it naturally stops growing.
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Skip the scalping. Cutting your grass too short before winter can stress it out and leave roots vulnerable.
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Clear debris. Rake or mulch fallen leaves and remove sticks or branches. A clean lawn surface reduces shady, damp areas where weeds like to settle.
When to Apply Fall Pre-Emergent to Warm Season Grass
This is the most important step for warm season lawns in fall. A pre-emergent herbicide, like Lawnbright’s Weed Wipeout, creates a barrier that prevents weed seeds from germinating.
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Timing matters. Apply in early fall before soil temperatures drop below 70°F. That’s when weeds like annual bluegrass, henbit, and chickweed are preparing to sprout.
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Water it in. Light watering helps activate the pre-emergent and form a protective shield in the soil.
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Don’t overseed. Unlike cool season lawns, warm season grass won’t establish new seed in fall. Overseeding now is a waste of time and money.
Spot Treat Existing Weeds
Even with pre-emergent down, you may see broadleaf weeds like clover or dandelion still lingering. This is the perfect time to tackle them.
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Use a targeted post-emergent herbicide and treat only the weeds you see.
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Avoid blanket spraying—your grass is preparing for dormancy and doesn’t need extra stress.
Adjust Watering
As your lawn slows its growth, it also needs less water.
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Cut back on watering frequency and let rainfall handle most of the job.
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Overwatering in fall is one of the fastest ways to encourage weeds, disease and fungus.
Prepare for Dormancy
Don’t worry if your lawn starts to lose its dark green color—it’s normal. Warm season grasses go dormant in the cooler months to conserve energy.
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Skip heavy fall fertilization. Nitrogen now won’t do much since your lawn isn’t actively growing. Save your big feedings for spring green-up and focus on high-phosphorus options that will strengthen roots or a winterizer that will help your turf store nutrients.
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Think long-term. A well-timed pre-emergent now will mean fewer weeds to fight when your lawn wakes up next year.
Pro Tip: Healthy Grass = Fewer Weeds
The best defense against weeds isn’t chemicals—it’s a thick, healthy lawn. Staying on schedule with weed prevention in fall, plus proper mowing and watering, keeps your warm season turf strong and reduces how many weeds you’ll have to deal with in the spring.
For warm season lawns, fall is all about weed prevention, not overseeding. By applying pre-emergent, tidying up your lawn, and easing off watering, you’ll set yourself up for a smoother, greener start when warm weather returns.
Lawnbright Plan Customer? Don’t worry! Our plan takes your grass type into account and sends you the products you need for fall. If you are a Prevent and Repair customer, Weed Wipeout pre-emergent is included in your box. Questions? Email us at info@getlawnbright.com or hit chat on the site.
Not a Lawn Plan Customer but want to fight weeds? Try our Weed Wipeout pre-emergent to fight crabgrass before it sprouts, and Pulverize post-emergent for broadleaf weeds you can already see. They’re all natural, pet-safe and effective.
Fall Weed Control FAQs
When should I apply pre-emergent to warm-season grass?
Apply fall pre-emergent before winter annual weeds begin establishing. For many warm-season lawns, that means watching for soil temperatures to begin approaching 70°F rather than relying on a specific calendar date.
Can I apply pre-emergent to Bermuda grass in fall?
Yes. Fall pre-emergent is commonly used on warm-season grasses such as Bermuda, Zoysia, Centipede, and St. Augustine to help prevent winter annual weeds.
Should I use pre-emergent or post-emergent weed control in fall?
It depends on the weeds you have. Pre-emergent is used to help prevent new weeds from establishing, while post-emergent products are used on weeds that are already visible and actively growing.
Do I need to overseed after controlling weeds?
Typically not for warm-season lawns in fall. Bermuda, Zoysia, Centipede, and St. Augustine are moving toward dormancy, so fall is generally a time to focus on weed prevention and lawn preparation rather than establishing new warm-season grass seed.