3 Best Weed and Feed for St Augustine 2026: Worth Your Money

3. Scotts Turf Builder Triple Action1

Scotts Turf Builder Triple Action1 is the three-in-one option that covers weed control, crabgrass prevention, and fertilization in a single 33.94 lb bag covering 12,000 sq. ft. For larger St. Augustine lawns where you want to minimize the number of seasonal applications, this product delivers the broadest label claims in the Scotts lineup.

The extended coverage area makes it the most cost-efficient choice per square foot.

Why I picked it

The pre-emergent crabgrass barrier is what sets this apart. St. Augustine doesn't compete well with crabgrass in thin areas, and applying a separate pre-emergent adds cost and labor.

Triple Action1 bundles that protection with a 2,4-D post-emergent herbicide and a 30-0-4 fertilizer, giving you three applications' worth of benefit in one pass. The 4.4-out-of-5 rating reflects solid performance, though some buyers noted the crabgrass prevention window is narrower than standalone pre-emergents.

Key specs

• Coverage area: 12,000 sq. ft. per bag
• NPK ratio: 30-0-4
• Active herbicides: 2,4-D and dithiopyr (pre-emergent)
• Application type: Granular, spreader-applied
• Bag weight: 33.94 lb
• Labeled for: St. Augustine, bermuda, zoysia, centipede, fescue, and bahia

Real-world experience

The most detailed buyer reports come from homeowners in the transition zone, places like middle Tennessee and North Carolina, where St. Augustine meets cooler-season grasses at the property edge. These users applied Triple Action1 in early spring when forsythia was blooming, which is the standard timing indicator for crabgrass pre-emergent activation.

Those who applied before soil temperatures hit 55°F for three consecutive days reported the strongest crabgrass suppression through June. If you're also thinking about what to plant in adjacent beds, our guide on best plants for hot dry climates covers species that won't compete with your lawn for nutrients.

Trade-offs

The pre-emergent component (dithiopyr) will prevent any grass seed from germinating for several months after application, so you cannot use this product if you plan to overseed thin areas. The large 33.94 lb bag is also heavy and awkward to handle, especially if you're loading a walk-behind spreader on a slope. And because it combines pre- and post-emergent herbicides, the application timing window is tighter: too early and the post-emergent won't contact existing weeds, too late and crabgrass has already germinated past the pre-emergent barrier.

How I picked

I evaluated each product on four specific criteria that matter for St. Augustine: herbicide compatibility with the species, nitrogen rate relative to the grass's growth cycle, coverage efficiency per application, and real-world buyer feedback from regions where St. Augustine is the dominant turf.

I cross-referenced manufacturer labels against university extension recommendations from the University of Florida IFAS and Texas A&M AgriLife, both of which publish species-specific guidance on herbicide tolerance.

I deliberately didn't test long-term soil health impacts beyond a single growing season, since phosphorus runoff and organic matter changes require multi-year study. I also didn't evaluate liquid spray alternatives, which are a different application category entirely. What I did focus on was granular spreader performance, since that's how most homeowners actually apply these products.

If you're maintaining your equipment alongside lawn care, our article on cleaning the air filter covers the kind of routine maintenance that keeps your spreader tractor or push mower running clean.

The buyer feedback analysis drew from verified purchase reviews across multiple retail platforms, looking specifically for reports that mentioned St. Augustine by name rather than generic "lawn" references. This filtering step matters because a product that works beautifully on tall fescue might scorch St.

Augustine under the same conditions.

Buying guide — what actually matters for Best Weed And Feed For St Augustine

Herbicide tolerance is non-negotiable

St. Augustine is one of the most herbicide-sensitive warm-season grasses. The species tolerates 2,4-D at labeled rates, but it can show leaf curl and temporary stunting if applied during heat stress above 90°F.

Products containing dicamba or MSMA carry higher burn risk and are generally not recommended for this grass. Always check the product label for an explicit St. Augustine listing before purchasing.

If your lawn is also showing signs of fungal issues, you may need to address that separately with a targeted treatment like those covered in our best fungicide for lawns guide.

Nitrogen rate should match the season

St. Augustine needs roughly 2 to 4 pounds of actual nitrogen per 1,000 sq. ft. per growing season, split across multiple applications. A single application of a 28-0-3 product at the labeled rate delivers roughly 0.35 lb of nitrogen per 1,000 sq. ft., which is appropriate for a mid-season feeding.

Jumping to a 32% nitrogen product in early spring can push tender new growth that's vulnerable to a late cold snap. Match the nitrogen intensity to the grass's current growth phase, not just the calendar date.

Pre-emergent versus post-emergent timing

If your main weed problem is crabgrass or goosegrass, you need a pre-emergent applied before soil temperatures reach 55°F for three consecutive days at a 4-inch depth. If you're dealing with existing broadleaf weeds like clover, dandelion, or chickweed, you need a post-emergent that contacts the leaf surface. Products that combine both, like Triple Action1, require you to hit a narrow window where the pre-emergent is still effective and the post-emergent has visible weeds to target.

Missing that window by even a week on either side reduces effectiveness significantly.

Coverage area and spreader calibration

A 5,000 sq. ft. bag sounds straightforward, but actual coverage depends on your spreader setting and walking speed. Most broadcast spreaders need to be set between 3.5 and 4.5 for Scotts granular products, but you should calibrate by weighing what your spreader dispenses over a measured 1,000 sq. ft. area before doing the full lawn. Over-application is the most common cause of St.

Augustine burn from weed-and-feed products, and it's entirely preventable with a kitchen scale and ten minutes of prep.

Watering requirements after application

Granular weed-and-feed products need moisture to activate the herbicide and move the fertilizer into the root zone. The standard recommendation is a quarter-inch of irrigation within 24 to 48 hours of application. If you rely solely on rainfall and a dry spell hits, the herbicide granules sit on the leaf surface without dissolving, and the fertilizer sits on the soil without moving into the root zone.

Neither component works well without that initial watering in.

Phosphorus considerations

All three products in this roundup carry a zero in the phosphorus position of their NPK ratio. That's intentional for regions with phosphorus runoff restrictions, but it means these products won't correct a phosphorus deficiency. If your soil test shows phosphorus below 20 ppm (Mehlich-3 extraction), you'll need a separate phosphorus application.

Sandy soils in the coastal Southeast are particularly prone to phosphorus deficiency, which shows up as purplish leaf blades and weak root development.

Frequently Asked Questions (FAQ)

Can I apply weed and feed to St. Augustine in the summer?

Yes, but with caution. St. Augustine is actively growing in summer, which means it can metabolize the herbicide more effectively than during dormancy.

However, air temperatures above 90°F increase the risk of temporary leaf burn from 2,4-D-based products. Apply in the early morning when temperatures are below 85°F, and water in the same day. SummerGuard is specifically formulated for this window because its insect control component targets the pests that peak in July and August.

How long after applying weed and feed can I mow?

Wait at least 48 hours after application before mowing. The herbicide needs time to absorb into the weed's leaf tissue, and mowing too soon removes the treated leaf surface before translocation occurs. For the fertilizer component, mowing after 48 hours also gives the granules time to dissolve and move into the soil, so you're not vacuuming up product with the clippings.

Will weed and feed kill crabgrass in St. Augustine?

Only if the product contains a pre-emergent herbicide like dithiopyr. Triple Action1 includes dithiopyr, which prevents crabgrass seeds from establishing. However, once crabgrass has germinated and developed more than two tillers, no weed-and-feed product will kill it effectively on St.

Augustine without risking turf damage. For established crabgrass, a targeted post-emergent like quinclorac is the standard recommendation, applied separately from your fertilizer schedule.

Is it safe to use weed and feed near vegetable gardens?

The 2,4-D component in most weed-and-feed products can drift as fine particulate or vapor, and it's particularly damaging to broadleaf vegetables like tomatoes, peppers, and beans. Maintain a buffer zone of at least 10 feet from garden beds, and apply only on calm days with wind speeds below 5 mph. If your lawn borders a garden, consider using a drop spreader instead of a broadcast spreader to minimize particle drift.

How often can I apply weed and feed to St. Augustine?

Most labels allow two to three applications per growing season, spaced at least 30 days apart. St. Augustine's total seasonal nitrogen requirement of 2 to 4 pounds per 1,000 sq. ft. means you'll likely need supplemental fertilizer applications beyond what weed-and-feed provides.

Over-applying herbicide stresses the turf and can lead to thinning, which ironically creates more space for weeds to establish.

Can I apply weed and feed right after aerating?

Wait at least two weeks after core aeration before applying any herbicide. Aeration opens the soil and creates fresh root exposure, which makes St. Augustine more susceptible to herbicide uptake and potential burn.

The fertilizer component is fine immediately after aeration, but the herbicide component needs the turf to recover its cuticle layer first.

Final verdict

The Scotts Turf Builder Weed and Feed 3 earns the top spot because it delivers the most balanced combination of broadleaf weed control and St. Augustine-safe fertilization. It's the product I'd reach for on an established lawn with moderate weed pressure and no major insect issues.

The 28-0-3 ratio feeds without pushing excessive growth, and the 2,4-D concentration is strong enough to kill existing weeds without scorching the turf when applied correctly.

For lawns dealing with chinch bugs or sod webworms in the heat of summer, the Scotts Turf Builder SummerGuard Lawn Food is the better choice. It sacrifices broadleaf weed control for insect protection, which is the right trade-off when insects are the primary threat.

If you're managing a large property and want to minimize seasonal applications, the Scotts Turf Builder Triple Action1 gives you the most coverage per bag and adds crabgrass prevention to the mix. Just remember that the pre-emergent component locks you out of any overseeding plans for the season.

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.