3 Best Grub Killer for St Augustine Grass 2026: Worth Buying

If you've noticed irregular brown patches spreading across your lawn this summer, there's a good chance you're dealing with a grub problem. Finding the Best Grub Killer For St Augustine Grass matters because this warm-season turf is especially vulnerable to white grub damage, and the wrong product can stress or even burn the grass you're trying to save. After comparing label specs, active ingredients, and hundreds of verified buyer reports, I've narrowed the field down to three products that consistently deliver results on St Augustine lawns.

Our top recommendation is the Scotts GrubEx1 Season Long Grub Killer. It offers the best balance of season-long protection, ease of application, and St Augustine safety based on aggregate user feedback. Below is a quick side-by-side comparison, followed by detailed breakdowns of each pick.

Comparison Chart of Best Grub Killer for St Augustine Grass

List of Top 3 Best Best Grub Killer for St Augustine Grass

I selected these three based on active ingredient effectiveness against white grubs, St Augustine grass tolerance, coverage area, and real-world buyer satisfaction. Each one takes a slightly different approach, so you can match the product to your specific situation.

Below are the list of products:

1. Scotts GrubEx1 Season Long Grub Killer

Scotts GrubEx1 is the product I recommend most often to homeowners dealing with their first serious grub outbreak on St Augustine. It uses chlorantraniliprole as the active ingredient, which is notably gentle on turf grasses while still delivering strong grub mortality rates. Verified buyer reviews consistently report visible results within 2 to 3 weeks of application during peak grub season.

Why I picked it

Chlorantraniliprole has a favorable safety profile for St Augustine grass, which is a real concern since this cultivar is sensitive to several common insecticides. In our research, this product stood out because it kills grubs for an entire season with a single application, saving you time and repeated treatments. It also earned a 4.5 out of 5 rating from thousands of buyers, which is consistently high for this category.

Key specs

• Active ingredient: Chlorantraniliprole 0.08%
• Coverage: 5,000 sq. ft. per bag
• Application type: Granular, spread with a broadcast or drop spreader
• Season-long protection from a single application
• Kills Japanese beetle grubs, white grubs, and billbugs
• Safe for use on St Augustine grass when applied per label directions

Real-world experience

Most buyers report the best results when applying GrubEx1 in late May through July, targeting young grubs before they grow large enough to cause severe root damage. One common pattern in reviews is that homeowners in the Southeast, where St Augustine dominates, see the brown patches stop spreading within 10 to 14 days. The granular formula works well with a standard lawn spreader, and watering it in after application activates the insecticide into the thatch layer where grubs feed.

If you're also dealing with broader lawn health issues, pairing this with a proper lawn fungicide treatment can help address multiple problems at once.

Trade-offs

GrubEx1 is a preventative and early-curative product, so it works best on small, newly hatched grubs rather than large mature ones already deep in the soil. If you're seeing heavy damage in late August or September, you may need a faster-acting curative insecticide first. Some buyers also note that the 5,000 sq. ft. bag falls short for larger lawns, requiring multiple purchases.

2. Southern Ag 006130 Atrazine St Augustine

Southern Ag Atrazine takes a different approach by combining weed control with St Augustine-specific formulation, making it a strong choice if your grub damage has opened the door to broadleaf weeds and crabgrass. Atrazine is one of the few herbicides labeled as safe for St Augustine grass, and this concentrate gives you precise control over mixing ratios.

Why I picked it

This product earned our Top Pick badge because it solves two problems at once: it suppresses winter annual weeds and controls existing broadleaf invaders in St Augustine turf. While it's technically a herbicide rather than a grub killer, many buyers use it as part of a combined treatment plan alongside a dedicated insecticide. The 32 oz concentrate covers a large area when mixed properly, making it a cost-effective option for bigger properties.

Key specs

• Active ingredient: Atrazine 42.2%
• Size: 32 oz liquid concentrate
• Application type: Spray, using a pump or hose-end sprayer
• Labeled for St Augustine grass, centipede grass, and St Augustine sod
• Controls henbit, chickweed, clover, and other winter annuals
• Covers approximately 1,000 to 2,000 sq. ft. per mixed gallon depending on application rate

Real-world experience

Buyers in the Gulf Coast states, where St Augustine is the default lawn grass, report that Southern Ag Atrazine works best when applied in late fall or early spring before weeds establish deep roots. Many users pair it with a separate grub control product in summer, creating a year-round protection strategy. The concentrate mixes cleanly with water and doesn't clog standard spray nozzles, which is a common complaint with cheaper atrazine alternatives.

If you're also planning to reseed or lay new sod, this product fits well into a broader lawn renovation plan that might include choosing the right fertilizer for soil recovery.

Trade-offs

This is not a grub killer, so if your primary problem is insect damage, you'll need a separate product like GrubEx1 or BioAdvanced. Atrazine is also restricted or banned in some states and municipalities due to groundwater concerns, so check your local regulations before purchasing. The concentrate requires careful measuring and mixing, which can be less convenient than a ready-to-spread granular product.

3. BioAdvanced Season Long Grub Control Granules

BioAdvanced Season Long Grub Control offers a compelling value proposition for homeowners who want season-long grub protection without paying a premium. The 10 lb bag covers a substantial area, and the active ingredient targets not just grubs but also mole crickets and chinch bugs, which are common secondary pests in St Augustine lawns.

Why I picked it

BioAdvanced earned the Best Budget badge because its cost per square foot is among the lowest in the category while still delivering reliable grub control. The product also kills mole crickets, which are a significant pest in Florida and Gulf Coast St Augustine lawns that many competing products ignore. With a 4.5 out of 5 buyer rating, it matches the Scotts option in user satisfaction at a lower price point.

Key specs

• Active ingredient: Imidacloprid 0.25%
• Coverage: 10 lb bag covers up to 5,000 sq. ft.
• Application type: Granular with broadcast or drop spreader
• Kills grubs, mole crickets, chinch bugs, and billbugs
• Season-long protection from a single application
• Water in after application to activate

Real-world experience

Verified buyer feedback shows that BioAdvanced performs well when applied in early summer before grub eggs hatch. Homeowners in central Florida, where mole crickets are a persistent problem alongside white grubs, report noticeable reductions in tunneling damage within two to three weeks. The granules spread evenly through a standard Scotts spreader set to a medium setting.

Some buyers mention that the product has a stronger chemical odor compared to GrubEx1, so wearing gloves and a mask during application is a good idea. For lawns that also need weed suppression, this pairs well with a separate insecticide treatment plan targeting multiple pest types.

Trade-offs

Imidacloprid has faced increased regulatory scrutiny due to its impact on pollinators, so avoid applying this product to any flowering clover or weeds that bees are actively visiting. The odor during application is noticeable and bothersome for some users. Additionally, imidacloprid-resistant grub populations have been documented in parts of the Northeast, so if you've used similar products in previous years without success, chlorantraniliprole-based GrubEx1 may be a better choice.

How I picked

I evaluated each product across four main criteria: active ingredient effectiveness against white grubs, St Augustine grass safety, coverage value, and real-world buyer satisfaction. I reviewed aggregated feedback from thousands of verified purchases, cross-referenced label claims with EPA registration data, and compared application methods for practicality. I also considered whether each product addresses secondary pests like mole crickets and chinch bugs, which frequently accompany grub damage in warm-climate lawns.

I deliberately did not test long-term soil impact beyond what label data and existing research indicate. I also did not evaluate performance on cool-season grasses like Kentucky bluegrass or fescue, since St Augustine has different chemical sensitivity thresholds. My focus was strictly on products that are explicitly labeled as safe for St Augustine cultivars, because herbicide burn is a real risk with off-label applications.

If you're maintaining other parts of your yard, you might also find our guide to best rakes for pine needles useful for general lawn cleanup after treatment.

Buying guide — what actually matters for Best Grub Killer For St Augustine Grass

Active ingredient and mode of action

The two most common active ingredients in grub killers are chlorantraniliprole and imidacloprid. Chlorantraniliprole, used in Scotts GrubEx1, works by affecting the grub's muscle function and is classified as a reduced-risk pesticide by the EPA. Imidacloprid, used in BioAdvanced, is a neonicotinoid that attacks the nervous system.

Both are effective, but chlorantraniliprole tends to have a wider safety margin for sensitive turf grasses like St Augustine.

St Augustine grass tolerance

Not all grub control products are safe for St Augustine. Some formulations containing certain herbicides can cause yellowing or thinning in this grass type. Always check the product label for explicit St Augustine or "St.

Augustine" listing before purchasing. Atrazine-based products like Southern Ag are among the few herbicides that St Augustine tolerates well, which is why they're so popular in the Southeast.

Application timing

Timing matters more than the product you choose. For preventative grub control, apply granular products in late May through early July when adult beetles are laying eggs and grubs are small and near the surface. Curative applications for visible damage work best in late summer, but you'll need a faster-acting product like one containing trichlorfon for large, mature grubs.

Missing the window by even two weeks can significantly reduce effectiveness.

Coverage area and product form

Granular products are easier for most homeowners to apply evenly using a standard broadcast spreader. Liquid concentrates like Southern Ag Atrazine require mixing and a sprayer but offer more precise control. Consider your lawn size: a 5,000 sq. ft. bag works for average suburban lots, but larger properties may need multiple bags or a concentrate that you can mix in bulk.

Secondary pest targeting

If you're in the Deep South, mole crickets and chinch bugs are almost as problematic as grubs. Products like BioAdvanced that list multiple target pests on the label save you from buying separate treatments. Check the pest list on the label to make sure it covers the specific insects damaging your lawn.

Regulatory restrictions

Some active ingredients, particularly atrazine and certain neonicotinoids, are restricted or banned in specific states and counties. Always verify that the product is legal to purchase and apply in your area. Your local cooperative extension office is a reliable source for current regulations.

Frequently Asked Questions (FAQ)

Can I apply grub killer and fertilizer at the same time?

Yes, you can apply granular grub control and fertilizer together as long as both products are compatible and labeled for simultaneous application. Many homeowners use a combination spreader setting to apply both in a single pass. However, avoid mixing grub killer with weed-and-feed products that contain herbicides unless the label explicitly permits it, since some herbicide combinations can stress St Augustine grass.

How long does it take for grub killer to work?

Preventative products like Scotts GrubEx1 and BioAdvanced typically show results within 10 to 14 days as young grubs ingest the treated soil and stop feeding. Curative products work faster, sometimes within 48 to 72 hours, but they require higher application rates and are harder on the turf. You may not see the brown patches recover immediately even after grubs are dead, since the grass needs time to regrow.

Is GrubEx1 safe for pets and children after application?

Once the granular product is watered in and the lawn has dried, it is generally safe for pets and children to resume normal activity. The EPA registration for chlorantraniliprole indicates low mammalian toxicity. However, keep pets and children off the lawn during application and until the granules have been watered in and the grass is completely dry, typically 24 hours.

What's the difference between GrubEx1 and BioAdvanced grub control?

The main difference is the active ingredient. GrubEx1 uses chlorantraniliprole, while BioAdvanced uses imidacloprid. Both provide season-long protection and cover similar areas.

Chlorantraniliprole is considered more targeted to grubs and less harmful to beneficial insects, while imidacloprid has a broader pest range including mole crickets and chinch bugs. Buyer ratings are nearly identical at 4.5 out of 5 for both.

When is the best time to apply grub killer to St Augustine grass?

The optimal window is late May through early July in most southern states, when Japanese beetles and other grub-producing insects are actively laying eggs. Applying during this period targets newly hatched grubs at their most vulnerable stage. In southern Florida and the Gulf Coast, you may need to apply slightly earlier due to the warmer soil temperatures that accelerate the beetle life cycle.

Final verdict

After comparing all three products across effectiveness, safety, and value, the Scotts GrubEx1 Season Long Grub Killer remains my top recommendation for most St Augustine lawns. Its chlorantraniliprole formula offers the best combination of grub-killing power and turf safety, with season-long protection from a single application.

If you're dealing with both weeds and grubs, the Southern Ag Atrazine is a smart companion product for St Augustine-specific weed control. For budget-conscious homeowners who also need mole cricket coverage, the BioAdvanced Season Long Grub Control Granules deliver excellent value without sacrificing performance.

Affiliate disclosure: This post contains affiliate links. If you buy through one of these links, I may earn a small commission at no extra cost to you. It never changes my recommendation, I only suggest gear I'd actually buy myself.