Best Weed and Feed for St Augustine Grass – 2025 Reviews

St. Augustine grass commonly battles broadleaf weeds like dandelion and clover, as well as grassy weeds such as crabgrass. Knowing what you’re up against helps pick the right herbicide—some products target specific weeds better than others.

For example, products with pre-emergent control stop weeds before they sprout, while post-emergent formulas tackle existing problems. I always recommend checking the label to ensure it covers your weed issues without harming the grass.

St. Augustine thrives with a balanced NPK ratio—look for something like 15-0-4 or similar, where nitrogen promotes green growth, potassium strengthens roots, and low phosphorus avoids overstimulation. Too much nitrogen can lead to thatch buildup or disease.

Slow-release formulas are your best friend here—they feed the grass gradually, reducing the risk of burn and providing steady nutrition. I’ve seen lawns respond much better to these compared to quick-release options that can cause stress.

Granular weed and feed is great for even coverage on larger lawns and often provides longer-lasting results, but it requires a spreader and can be messy if not calibrated properly.

Liquid sprays, on the other hand, are perfect for spot treatments or smaller areas—they’re easier to apply precisely but may need more frequent reapplication. Personally, I prefer granules for overall lawn care and keep a spray handy for quick fixes.

Apply weed and feed during active growth periods—typically spring and fall for St. Augustine—when the grass can recover quickly and weeds are most vulnerable. Avoid summer heat stress or winter dormancy, as the product might not be as effective or could damage the lawn.

I always remind folks to water the lawn before applying granules to help them stick and activate, and follow up with light watering after to wash the product into the soil without runoff.

St. Augustine can be sensitive to certain herbicides like 2,4-D if overused, so always opt for products labeled specifically for Southern grasses or St. Augustine. Spot-testing a small area first can save you from widespread damage.

If you have pets or children, look for formulas that dry quickly or require minimal re-entry time. I’ve found that following label instructions to the letter is the best way to keep your lawn—and family—safe.

Calculate coverage based on your lawn size—overspending on a huge bag for a small yard is wasteful, while underestimating can leave weeds unchecked. Most products list square footage, so measure your space first.

Consider environmental factors like runoff into waterways; slow-release granules and organic options tend to be more eco-friendly. In my experience, investing in a quality product that matches your lawn’s needs ultimately saves money and reduces chemical use over time.

No, St. Augustine grass is sensitive to certain herbicides commonly found in weed and feed products, so it’s crucial to choose one specifically formulated for Southern grasses or labeled safe for St. Augustine. Using the wrong product can cause yellowing, stunting, or even kill patches of your lawn.

I always check the ingredients—look for compatibility with St. Augustine and avoid high concentrations of chemicals like atrazine if not recommended.

Typically, once or twice a year during the growing season—spring and fall—is sufficient for most weed and feed products. Overapplication can lead to fertilizer burn or herbicide resistance, so follow the product label carefully.

In my testing, I’ve found that slow-release formulas often require less frequent applications, while liquids might need touch-ups every few months for persistent weeds.

St. Augustine commonly faces broadleaf weeds like dollarweed, clover, and dandelion, as well as grassy weeds such as crabgrass. Products with pre-emergent control are great for preventing crabgrass, while post-emergent herbicides target existing broadleaf weeds.

From my reviews, options like Fertilome St. Augustine Weed & Feed excel at both, but always match the product to your specific weed problems for the best results.

Most weed and feed products are safe once dry, which usually takes a few hours to a day. However, I recommend keeping pets off the lawn during application and until the product has been watered in and fully absorbed to avoid ingestion or skin irritation.

Check the label for specific re-entry times, and consider pet-friendly alternatives if you have animals that spend a lot of time on the grass.

It’s generally not recommended to apply weed and feed during peak summer heat, as St. Augustine grass is under stress from high temperatures and drought. Herbicides can cause additional damage, and the grass may not recover well.

Stick to spring or fall applications when the grass is actively growing and better able to handle the treatment. If you must treat weeds in summer, opt for spot treatments rather than a full lawn application.