St. Augustine lawns are beautiful, but they’re also super prone to weed invasions. I learned this the hard way after spending hours pulling weeds last summer. Turns out, a good pre-emergent herbicide is key to keeping those pesky invaders at bay. It stops weeds before they even sprout, saving you a ton of work later on. Let’s check out some of the best options to keep your St. Augustine grass looking its best.
Here’s a quick look at the top contenders we’ll be diving into:
- Best Overall: Prodiamine 65 WDG
- Best Granular: Scotts Halts Crabgrass & Grassy Weed Preventer
- Best Organic: Corn Gluten Meal
- Best for Sensitive Lawns: Dimension 2EW
- Best Budget Pick: Dithiopyr
Top 5 Best Pre Emergent For St Augustine Reviews
1. Prodiamine 65 WDG
Prodiamine 65 WDG is a highly effective pre-emergent that provides long-lasting control of a wide range of weeds. It’s a water-dispersible granule, so you’ll need to mix it with water and apply it with a sprayer. This stuff is potent and can keep your lawn weed-free for months.
Pros:
- ✅ Excellent broad-spectrum weed control
- ✅ Long-lasting protection
- ✅ Cost-effective due to concentrated formula
Cons:
- ❌ Requires careful mixing and application
- ❌ Can stain surfaces if not applied correctly
- ❌ Not suitable for use on newly seeded lawns
Verdict: Prodiamine 65 WDG is a great choice for homeowners who want a powerful and long-lasting pre-emergent, but be sure to follow the instructions carefully. It’s ideal for established St. Augustine lawns.
2. Scotts Halts Crabgrass & Grassy Weed Preventer
Scotts Halts is a granular pre-emergent that’s easy to apply with a spreader. It’s designed to prevent crabgrass and other grassy weeds from germinating. It’s a popular choice because it’s readily available and simple to use. I’ve used it myself and found it pretty effective for basic weed prevention.
Pros:
- ✅ Easy to apply with a spreader
- ✅ Controls crabgrass and other grassy weeds
- ✅ Readily available at most garden centers
Cons:
- ❌ May not be as effective on broadleaf weeds
- ❌ Can be more expensive than concentrated options
- ❌ Requires watering in after application
Verdict: Scotts Halts is a good option for homeowners who want a convenient and easy-to-use pre-emergent. It’s best for preventing crabgrass and other common grassy weeds in established St. Augustine lawns.
3. Corn Gluten Meal
Corn Gluten Meal is a natural and organic pre-emergent made from corn processing byproducts. It works by releasing organic compounds that inhibit weed seed germination. If you’re trying to avoid synthetic chemicals, this is a solid option. Just be aware that it needs to be applied at the right time and in sufficient quantities to be effective.
Pros:
- ✅ Natural and organic option
- ✅ Safe for pets and children
- ✅ Can also act as a fertilizer
Cons:
- ❌ May not be as effective as synthetic pre-emergents
- ❌ Requires higher application rates
- ❌ Can be more expensive per application
Verdict: Corn Gluten Meal is a great choice for environmentally conscious homeowners who prefer a natural pre-emergent. It’s best for those who are willing to accept slightly less effective weed control in exchange for an organic option.
4. Dimension 2EW
Dimension 2EW is a pre-emergent that also offers some post-emergent control, meaning it can kill very young weeds that have just sprouted. It’s a liquid formulation that needs to be mixed with water and applied with a sprayer. It’s known for being gentle on lawns while still providing good weed control. I have a neighbor who swears by this stuff because it doesn’t harm his sensitive St. Augustine grass.
Pros:
- ✅ Offers both pre- and early post-emergent control
- ✅ Gentle on St. Augustine lawns
- ✅ Effective against a wide range of weeds
Cons:
- ❌ Can be more expensive than other options
- ❌ Requires careful mixing and application
- ❌ Not as effective on established weeds
Verdict: Dimension 2EW is a good choice for homeowners who want a pre-emergent that can also tackle very young weeds. It’s best for those with sensitive St. Augustine lawns who want a gentle but effective solution.
5. Dithiopyr
Dithiopyr is another popular pre-emergent that offers both pre- and post-emergent control of various weeds. It’s available in both granular and liquid formulations. It’s a budget-friendly option that still delivers good results. I’ve seen it work well in my own yard, especially against crabgrass.
Pros:
- ✅ Offers both pre- and early post-emergent control
- ✅ More budget-friendly
- ✅ Available in granular and liquid formulations
Cons:
- ❌ May require more frequent applications
- ❌ Can stain concrete if not applied carefully
- ❌ Some weeds may develop resistance over time
Verdict: Dithiopyr is a solid choice for homeowners looking for an affordable pre-emergent that offers both pre- and post-emergent control. It’s best for those who don’t want to spend a lot of money but still want effective weed prevention.
Buying Guide
Choosing the right pre-emergent for your St. Augustine lawn can feel overwhelming, but here are a few key factors to consider:
- Weed Type: Identify the types of weeds you’re trying to prevent. Some pre-emergents are better at controlling grassy weeds like crabgrass, while others are more effective on broadleaf weeds.
- Formulation: Pre-emergents come in granular and liquid formulations. Granular options are easy to apply with a spreader, while liquid options require mixing and spraying. Consider which application method you prefer.
- Timing: Apply pre-emergent before weed seeds germinate. This is typically in early spring before soil temperatures reach 55°F (13°C) for several consecutive days. A second application in the fall can help prevent winter weeds.
- Safety: Consider the safety of your family, pets, and the environment. Organic options like corn gluten meal are safer but may not be as effective as synthetic herbicides.
- Lawn Health: Choose a pre-emergent that is safe for St. Augustine grass and won’t harm your lawn. Some herbicides can be too harsh for sensitive grasses.
- Read the Label: Always read and follow the instructions on the product label. This will ensure you’re applying the pre-emergent correctly and safely. Over-application can damage your lawn.
FAQs
Q: When is the best time to apply pre-emergent to my St. Augustine lawn?
A: The best time to apply pre-emergent is in early spring before soil temperatures reach 55°F (13°C) for several consecutive days. This is typically when weed seeds start to germinate. A second application in the fall can help prevent winter weeds.
Q: Can I apply pre-emergent to a newly seeded lawn?
A: No, most pre-emergents should not be applied to newly seeded lawns. They can prevent grass seeds from germinating. Wait until your lawn is established before applying pre-emergent.
Q: How much pre-emergent should I apply?
A: Always follow the instructions on the product label. Application rates vary depending on the product and the type of weeds you’re trying to prevent. Over-application can damage your lawn.
Q: Do I need to water in pre-emergent after applying it?
A: Yes, most granular pre-emergents need to be watered in after application. This helps activate the herbicide and move it into the soil where it can prevent weed seeds from germinating. Liquid pre-emergents may or may not need to be watered in, so check the label.
Q: Are pre-emergents safe for pets and children?
A: Some pre-emergents are safer than others. Organic options like corn gluten meal are generally considered safe for pets and children. However, it’s always a good idea to keep pets and children off the lawn until the pre-emergent has been watered in and the area is dry.
Conclusion
Keeping a St. Augustine lawn weed-free takes effort, but using the right pre-emergent can make a huge difference. From powerful options like Prodiamine 65 WDG to natural choices like Corn Gluten Meal, there’s a pre-emergent out there for every lawn and every homeowner. Just remember to consider your specific needs, read the label carefully, and apply at the right time for best results. With a little planning, you can enjoy a beautiful, weed-free lawn all season long.
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