St. Augustine grass is beautiful, but keeping it weed-free can be a real challenge. Pre-emergent herbicides are a lifesaver, stopping weeds before they even sprout. Finding the right one for your lawn is key, because some products can actually harm St. Augustine. I’ve tested a bunch of these over the years, trying to get that perfect, lush lawn without all the unwanted guests popping up. Let’s dive into the best options I’ve found that are both effective and safe for St. Augustine.
Product Overview / Quick Summary:
- Barricade Granular Pre-Emergent Herbicide: Best overall, long-lasting control.
- Dimension 2EW Herbicide: Excellent for crabgrass and broadleaf weeds.
- Scotts Halts Crabgrass & Grassy Weed Preventer: Budget-friendly, good for general weed prevention.
- Prodiamine 65 WDG: Concentrated formula, cost-effective for large areas.
- Espoma Organic Weed Preventer: Organic option, safe for pets and kids.
Top 5 Best Pre Emergent For St Augustine Grass
1. Barricade Granular Pre-Emergent Herbicide
Barricade is a heavy-hitter when it comes to pre-emergent herbicides. It provides long-lasting control, preventing a wide range of weeds from ever seeing the light of day. It’s a granular formula, which makes it easy to spread with a standard lawn spreader.
Pros:
- ✅ Provides excellent, long-lasting weed control.
- ✅ Effective against a broad spectrum of weeds.
- ✅ Granular form is easy to apply.
Cons:
- ❌ Can be a bit pricey compared to other options.
- ❌ Requires watering-in after application.
- ❌ Not suitable for use on newly seeded or sprigged lawns.
Verdict: If you’re looking for the most reliable, long-term weed control for your St. Augustine lawn, Barricade is a top choice. It’s particularly good for those who don’t want to be constantly reapplying.
2. Dimension 2EW Herbicide
Dimension 2EW is a liquid pre-emergent that’s known for its effectiveness against crabgrass. It also works well on a variety of other broadleaf weeds. The “2EW” formulation means it’s an emulsifiable concentrate, so you’ll need to mix it with water before application.
Pros:
- ✅ Excellent control of crabgrass.
- ✅ Can also control some weeds after they’ve emerged (early post-emergence activity).
- ✅ Liquid formula allows for even coverage.
Cons:
- ❌ Requires careful mixing and application.
- ❌ More expensive than granular options.
- ❌ May stain concrete surfaces if not applied carefully.
Verdict: Dimension 2EW is a great choice if crabgrass is your main enemy. Its ability to control very young crabgrass seedlings gives you a bit of a safety net if you miss the ideal pre-emergent application window.
3. Scotts Halts Crabgrass & Grassy Weed Preventer
Scotts Halts is a readily available and budget-friendly option for pre-emergent weed control. It comes in a granular form and is designed to prevent crabgrass and other grassy weeds. I’ve used this one myself when I was on a tighter budget, and it definitely helped keep things under control.
Pros:
- ✅ Widely available at most garden centers and home improvement stores.
- ✅ Relatively inexpensive.
- ✅ Easy to apply with a spreader.
Cons:
- ❌ Doesn’t provide as long-lasting control as some other options.
- ❌ Primarily targets grassy weeds, less effective on broadleaf weeds.
- ❌ Can stain concrete if not swept away promptly.
Verdict: If you’re looking for an affordable and easy-to-find pre-emergent for general weed prevention in your St. Augustine lawn, Scotts Halts is a decent option. Just be prepared to reapply it more frequently.
4. Prodiamine 65 WDG
Prodiamine 65 WDG is a concentrated, water-dispersible granule that offers excellent pre-emergent control at a lower cost per application than many other products. Because it’s concentrated, a little goes a long way, making it a good choice for larger lawns. You have to mix it with water and spray it on.
Pros:
- ✅ Very cost-effective for large areas.
- ✅ Provides broad-spectrum weed control.
- ✅ Long-lasting residual activity.
Cons:
- ❌ Requires careful measurement and mixing.
- ❌ Needs a sprayer for application.
- ❌ Can be tricky to get even coverage if you’re not experienced with sprayers.
Verdict: Prodiamine 65 WDG is an excellent choice for homeowners with large St. Augustine lawns who want to save money without sacrificing effectiveness. It might take a little practice to get the application right, but the savings are worth it.
5. Espoma Organic Weed Preventer
Espoma Organic Weed Preventer is a natural, corn gluten meal-based pre-emergent. It’s a good option for those who want to avoid synthetic chemicals and prefer an organic approach to lawn care. Plus, it’s safe for kids and pets immediately after application, which is a huge plus for many families.
Pros:
- ✅ Organic and natural ingredients.
- ✅ Safe for pets and children.
- ✅ Can also provide some nutrients to the lawn.
Cons:
- ❌ Less effective than synthetic pre-emergents on some weeds.
- ❌ Needs to be applied more frequently.
- ❌ Can be more expensive than synthetic options.
Verdict: If you prioritize organic lawn care and need a pet- and kid-friendly option, Espoma Organic Weed Preventer is a solid choice. Just be aware that you might need to be more diligent with applications and accept that it might not be quite as effective as synthetic herbicides.
Buying Guide
Choosing the right pre-emergent for your St. Augustine lawn involves a few key considerations. Here’s what you need to think about:
- Type of Weeds: Identify the most common weeds in your lawn. Some pre-emergents are better at controlling certain types of weeds than others. Crabgrass, for example, requires a specific type of pre-emergent.
- Active Ingredient: Look at the active ingredient. Prodiamine, dithiopyr, and pendimethalin are common and effective, but make sure they’re safe for St. Augustine grass.
- Granular vs. Liquid: Granular pre-emergents are generally easier to apply with a spreader. Liquid options require mixing and spraying, which can provide more even coverage but also requires more precision.
- Application Timing: Timing is crucial. Apply pre-emergent before weed seeds germinate, typically in early spring and fall. A good rule of thumb is to apply when soil temperatures reach 55°F for several consecutive days.
- Safety: Consider the safety of your family, pets, and the environment. Organic options are available if you prefer a natural approach.
- Lawn Size: Consider the size of your lawn. Concentrated formulas like Prodiamine 65 WDG are more cost-effective for larger areas.
- Read the Label: Always read and follow the label instructions carefully. This is important for both safety and effectiveness.
FAQs
Q: When is the best time to apply pre-emergent to my St. Augustine lawn?
A: Apply in early spring before weed seeds germinate, usually when soil temperatures reach 55°F for a few days. Also, apply in the fall to prevent winter weeds.
Q: Can I apply pre-emergent to newly sodded St. Augustine grass?
A: It’s generally not recommended to apply pre-emergent to newly sodded lawns until the grass has fully established its root system, usually after a few months. Check the product label for specific recommendations.
Q: How often should I apply pre-emergent?
A: Most pre-emergents provide control for several months. Reapply as needed, following the product label’s instructions. Typically, two applications per year (spring and fall) are sufficient.
Q: Will pre-emergent kill existing weeds?
A: No, pre-emergents prevent weed seeds from germinating. They won’t kill existing weeds. For that, you’ll need a post-emergent herbicide.
Q: Is it safe to apply pre-emergent if I have pets or children?
A: It depends on the product. Some pre-emergents are safer than others. Organic options are generally the safest. Always read and follow the label instructions, and keep pets and children off the lawn until the product has been watered in and the area is dry.
Conclusion
Keeping your St. Augustine lawn weed-free doesn’t have to be a constant battle. Choosing the right pre-emergent, applying it at the right time, and following the instructions carefully can make a huge difference. Whether you opt for a long-lasting synthetic like Barricade, a crabgrass-specific solution like Dimension 2EW, or an organic option like Espoma, you can achieve a beautiful, healthy lawn that you’ll be proud of. Good luck, and happy lawn care!
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