Will Vinegar Kill St. Augustine Grass?

As a long-time gardener and lawn care enthusiast, I’m often asked if vinegar can be used to kill weeds in St. Augustine grass. This warm season turf grass is prized for its deep green color and lush texture, but it can be prone to invasion from stubborn broadleaf and grassy weeds. Vinegar has gained popularity as a natural weed killer, but many homeowners are hesitant to use it in their St. Augustine lawns for fear it will harm the grass. From my experience, vinegar can be effective against weeds, but it must be used judiciously in St. Augustine turf.

In this article, I’ll share what I’ve learned from testing vinegar in my own St. Augustine lawn over the years. You’ll discover how vinegar affects St. Augustine grass when used as a herbicide, get tips for using vinegar safely for spot treating weeds, and learn whether vinegar works on common intruders like crabgrass and nutsedge. I’ll also provide a look at some other natural weed control alternatives, so you can make the best decision for keeping your St. Augustine looking its best.

There’s a lot of misleading information out there about vinegar and St. Augustine grass, so I’m excited to finally set the record straight. There are definitely right and wrong ways to use vinegar in warm season lawns, so keep reading to get the inside scoop from a seasoned gardener. Let’s dive in!

How Does Vinegar Affect St. Augustine Grass?

As a warm season turfgrass, St. Augustine is routinely plagued by weeds, especially during the hot and humid summer months. For homeowners seeking natural weed control options, vinegar seems like an ideal solution. But there’s a lot of conflicting information out there about whether vinegar harms St. Augustine grass itself when sprayed as a herbicide.

Through trial and error in my own lawn, I’ve learned that vinegar can damage St. Augustine if used improperly. The key is understanding how to use vinegar selectively and in moderation when managing weeds in St. Augustine turf.

Can Vinegar Be Used as a Natural Weed Killer in St. Augustine Lawns?

Absolutely! When applied correctly, vinegar can be an effective weed control agent for St. Augustine grass.

The acetic acid in vinegar works as a non-selective herbicide, meaning it will kill any plant tissue that it comes into direct contact with. Weeds like crabgrass, dandelions, and clover don’t stand a chance against a concentrated hit of vinegar.

However, vinegar tends to perform best as a spot treatment for individual weeds rather than a total lawn application. I’ve found that spraying a small amount directly onto weed leaves or stems is the best approach for St. Augustine turf. This minimizes any risk of damaging the established grass while still knocking out the invaders.

What Concentration of Vinegar is Needed to Kill Weeds in St. Augustine Grass?

For the best weed killing power, I recommend using horticultural vinegar containing 20% acetic acid or more. Grocery store vinegar just won’t cut it when it comes to herbicide effectiveness.

Look for horticultural vinegar sold at garden centers – concentrates around 30% or higher work best. Some research also shows that adding a small amount of dish soap helps the vinegar stick to weed leaves better for improved contact.

Always follow the product label instructions for exact dilution rates. But generally, mixing 1 part horticultural vinegar with 1-2 parts water is sufficient for killing weeds and unwanted grass in St. Augustine lawns when spot treating.

Is Vinegar Harmful to Established St. Augustine Turf?

Vinegar and St. Augustine Grass

Vinegar doesn’t discriminate when it comes to plant death, which is why caution is needed when using it around valued St. Augustine grass. Concentrated vinegar can potentially burn and damage St. Augustine blades and roots if allowed to contact them directly.

However, some periodic sodium bicarbonate treatments for your St. Augustine grass a couple of times a year and before the vinegar application can help increase its tolerance and make it more resistant to low concentrations of vinegar, when applied selectively as a spot treatment. This works similarly to treating lawns with triclopyr before using a weed and feed type product.

The key is using a targeted spraying approach, rather than hosing down the entire lawn with vinegar. Spot treat weeds individually and carefully shield any nearby St. Augustine grass to avoid inadvertent damage. Limit vinegar use to calm, dry days without wind. With careful, selective application, vinegar can be extremely effective on weeds invading St. Augustine grass.

Using Vinegar Safely in St. Augustine Grass

Now that you know vinegar can be used to kill weeds in St. Augustine, it’s crucial to learn how to apply it properly. Using vinegar irresponsibly can lead to unintended damage, so caution is key when using it as a herbicide. After many vinegar experiments in my lawn, here are my top tips for success.

Tips for Spot Treating Weeds with Vinegar in St. Augustine Lawns

Spot treatment is the best approach for using vinegar around St. Augustine grass. Here are some recommendations:

  • Use a small spray bottle for targeted application on individual weeds. Adjust the nozzle to a narrow stream to control spray width.
  • Add a couple drops of dish soap to help the vinegar adhere and penetrate weed leaves. Mark the spray bottle clearly so it’s not confused with other products.
  • Limit vinegar use to calm days without wind, which can cause drift onto grass. Carefully shield any nearby ornamentals and grasses with a piece of cardboard while spraying.
  • Aim for complete leaf coverage when spraying weeds, wetting all foliage for maximum contact. Reapply to stubborn weeds in a couple weeks if needed.
  • Watch for overspray on St. Augustine blades. Rinse off any accidental contact immediately with water to prevent turf damage. Monitor grass health closely after application.
  • Hand pull larger weeds after spraying once they are visibly damaged and easy to uproot. This prevents re-growth.
  • Dispose of pulled weeds properly, away from planting beds where vinegar residue could impact plants. Rinse hands after any contact.

Following these precautions, I’ve had great success selectively eliminating weeds like dollarweed, clover and dandelions from my St. Augustine lawn using vinegar.

When to Avoid Using Vinegar for Weed Control in St. Augustine Grass

While vinegar is an asset for spot treating weeds in St. Augustine during the growing season, there are times when caution is warranted:

  • Avoid use during new grass establishment, as young roots are especially vulnerable. Mature, healthy turf can better withstand limited exposure.
  • Do not apply during drought or heat stress, when grass is less resilient. Vinegar application under these conditions almost always results in setbacks.
  • Limit use when turf is going dormant or transitioning in winter, as growth has slowed. Grasses are unable to recover quickly from injury during these times.
  • Do not exceed spot treatment, even if weeds are prevalent. Broad spray application of vinegar significantly raises the risks to St. Augustine grass.

Essentially, reserve vinegar as a selective spot treatment only during optimal growing conditions for mature, established St. Augustine turf. Pay close attention to grass health and dial back use if any concerns arise.

Other Natural Weed Control Options for St. Augustine Lawns

Vinegar isn’t the only natural herbicide out there. Some other options I’ve found effective on weeds while safer for use around St. Augustine include:

  • Corn gluten meal prevents seeds from germinating, when applied pre-emergently. It does not kill mature weeds.
  • Boiling water kills weed seedlings and tender young growth when poured directly on unwanted plants.
  • Manual hand pulling can eliminate many annual weeds and juvenile perennials with shallow roots.
  • Solarization uses clear plastic to “bake” weeds through elevated ground temperatures in summer.
  • Products with citric acid extracts like lemon juice also offer selective post-emergent control, though higher concentrations are needed.

Experiment with these alternative natural methods to find the best fit for your St. Augustine weed problems, reducing reliance on vinegar alone. An integrated approach is ideal for the healthiest turf.

The Impact of Vinegar on Common St. Augustine Weeds

St. Augustine lawns deal with a range of warm-season weed threats, from grassy invaders like crabgrass to stubborn broadleaves such as clover and nutsedge. I always get questions about which specific weeds vinegar works on in these lawns, so let’s explore some of the most common targets:

Does Vinegar Effectively Kill Crabgrass in St. Augustine Grass?

In my experience, vinegar is one of the best organic herbicides for controlling crabgrass in St. Augustine turf and other lawn grasses. The acetic acid quickly penetrates the leaves and stems of actively growing crabgrass, turning foliage yellow before killing the entire plant.

Target young crabgrass plants in early summer for the best results. Mature crabgrass is harder to control with vinegar alone since the wiry stems and roots are protected by tough foliage. Repeated applications are usually needed on established clumps.

Use a spray bottle to completely douse small patches of crabgrass. For larger infestations, use vinegar as a follow-up treatment after hand-digging clumps to finish off any remaining stems and stragglers.

Vinegar works well on crabgrass without the toxicity concerns of many traditional herbicides, making it ideal for use around kids and pets once dried. Just take care to avoid overspray on desired grass.

Will Vinegar Kill Dallisgrass in St. Augustine Lawns?

Dallisgrass is a perennial weed that can be challenging to control. However, I’ve had great success using concentrated vinegar as a spot treatment to eradicate young dallisgrass just emerging in early spring.

Repeated applications are needed on mature clumps with established root systems and wiry stems. For larger patches, it’s best to hand dig first to remove the bulk of the plant. Follow up with targeted vinegar spraying to finish the job on any remaining growth.

The key is persistence and hitting dallisgrass early before rhizomes spread. Used properly as part of an integrated strategy, vinegar can keep dallisgrass from taking over St. Augustine turf.

Is Vinegar Effective Against Nutsedge Weeds in St. Augustine Turf?

In my experience, standard horticultural vinegar at 20% acetic acid or less has very limited effect on difficult perennial sedges like purple and yellow nutsedge.

The waxy leaf surface causes vinegar to bead up and run off rather than penetrating. Concentrations of at least 30% are needed to achieve adequate sedge control.

For nutsedge, I’ve found that using a surfactant additive helps substantially. It allows the vinegar to spread out and coat weed leaves rather than balling up. Pelargonic acid (a naturally occurring fatty acid) also offers good nutsedge control with less risk to desirable grasses.

Either way, don’t expect quick results on nutsedge from vinegar or other organic herbicides. Repeated applications are necessary to deplete the plant’s extensive underground tuber reserves. But it can be done with persistence!

In summary, vinegar can be a powerful natural weapon against many common St. Augustine grass weeds, with proper application techniques. Always monitor grass health closely and respond promptly if any inadvertent injury occurs. With smart, selective use, vinegar offers inexpensive, non-toxic weed control for your lawn.


When using vinegar for weed control in St. Augustine lawns, there are some key questions that always seem to come up. After years of fielding inquiries from homeowners about vinegar, here are the topics I get asked about the most:

What concentration of vinegar works best for weed control in St. Augustine grass?

From my experience, a horticultural vinegar concentrate of 20% acetic acid or higher is best for controlling weeds in St. Augustine turf and other lawn grasses. Look for a specialty horticultural vinegar sold at garden centers and nurseries, not the 5% grocery store variety!

I’ve found that 30% concentrations tend to work faster and more effectively than weaker 20% solutions. But follow label precautions carefully, as these higher vinegar strengths can quickly cause damage if misapplied.

Always dilute the horticultural vinegar concentrate based on label instructions before use. Normally a 1:1 or 1:2 ratio of vinegar to water is recommended. The final spray solution applied should contain at least 10% acetic acid for weed killing action.

How long does it take for vinegar to kill weeds in St. Augustine lawns?

With the right vinegar strength and application, most weeds in St. Augustine grass will start showing effects within a few hours of spraying. Sensitive annual weeds like chickweed may die very quickly, while tougher perennials like dandelions take longer.

Typically, I tell homeowners to expect 2-4 days before weeds are completely dead and dry following vinegar treatment. Crabgrass and foxtails turn yellowish and then brown within 2-3 days. Broadleaf weeds like clover take 3-4 days to fully desiccate.

Don’t be impatient and reapply too soon, as this risks harming the St. Augustine. Wait and monitor weed health. Hand pull plants once they are dead and dry to prevent any potential regrowth.

Should I only spot treat weeds with vinegar in St. Augustine grass?

Spot treatment is strongly recommended over broad applications of vinegar in St. Augustine lawns, in order to limit the risks of turf injury.

Use a spray bottle to precisely target individual weeds. Shield nearby grass blades from any potential overspray or drift. Limit use only to actively growing weeds on calm days without wind.

While vinegar can selectively kill weeds when applied properly, any contact with St. Augustine foliage risks damaging the grass. Erring on the side of caution and spot treating is the smartest approach for weed control with minimal risks to your healthy lawn.

I hope these answers provide some helpful perspective on using vinegar safely and effectively in St. Augustine turf. Always observe label precautions, start with limited test areas, and monitor grass health closely to catch any problems right away. Let me know if you have any other vinegar questions – I’m always happy to share what I’ve learned from my hands-on experience!

In Conclusion

After reading this article, you should now have a solid grasp of how to use vinegar safely and effectively for weed control in St. Augustine lawns. While vinegar can damage St. Augustine grass if used carelessly, it can also be an inexpensive, non-toxic tool for managing common weeds when applied selectively and correctly.

The key takeaways around using vinegar as an organic herbicide in St. Augustine turf include:

  • Spot treat weeds individually rather than blanketing the entire lawn
  • Use horticultural vinegar concentrates, not household products
  • Shield grass blades and rinse any accidental overspray
  • Enhance results by adding a surfactant
  • Repeat applications may be needed on mature weeds
  • Monitor grass health closely afterward for any signs of injury
  • Consider alternate natural controls like corn gluten meal too

I hope these vinegary tips help you banish weeds from your St. Augustine lawn safely and effectively. Always observe best practices for vinegar use around any desired grass. With smart, cautious application, you can harness the weed-killing power of vinegar without harming your prized St. Augustine turf.

If you have any other lawn care questions, don’t hesitate to ask! I’m always happy to share advice from my many years of hands-on experience. Wishing you a lush, weed-free lawn this summer!

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