Best Lawn Pre-Emergent to Kill Weeds Before They Exist

Do you hate lawn weeds so much that you want to murder their seeds before they have a chance to germinate? Well, you’re in the right place (you monster!). Welcome, fellow lawn lunatic! Join me for a detailed (and helpful) discussion of the best lawn pre-emergent herbicide products to prevent annual weed germination and make your neighbors feel inferior.

Applying pre-emergent herbicide is the best way to control those stubborn annual weeds that will come back every season (if you let them).

You can buy these products in liquid or granular form, and I have some real beauties of each type that I’ll recommend on this page.

But if you’re just here for the best-of-the-best: Dimension 2EW is my recommendation as the best lawn pre-emergent herbicide. Its core ingredient is dithiopyr, which is not only capable of blocking weed seed germination, but it will also kill actively growing weeds. This makes it more forgiving than other products out there – if you make a mistake with the timing of your application, it will still work well for you.

More importantly, you won’t be stuck writing a bitter 1-star review at 3 in the morning with crabgrass stuck under your fingernails.

And you won’t wake up the next morning to a condescending reply explaining that you should have checked the soil temperature and applied the product a week earlier.

Who needs that kind of pressure (or judgment)? Dimension 2EW is pretty fool-proof, and let’s be real — we could all use more products like that in our life.

But just in case my go-to pre-emergent herbicide isn’t the perfect fit for you (or you don’t want your broadcast spreader to get jealous) I have some additional product recommendations for you below.

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My Favorite Lawn Pre-Emergent Products

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Avoiding Some Common Mistakes I See

There are a number of pre-emergent lawn herbicides on the market, and if you take a minute to read reviews for these products you’ll find that they are usually one of two extremes:

• Some people have great results,
• Others claim the products just don’t work.

But for most people the difference in results usually comes down to execution, not product.

The reality is that most can work great for you, but you need to know a little bit about what’s in these products and how they work (and when they won’t work) for a successful application.

So before we go any farther, let’s take a look at exactly what you need to know to buy the best pre emergent product for your lawn, and I’ll share my tips to use each type of product properly.

This information will help you to avoid common mistakes that a lot of homeowners make.

And getting the most out of your investment in any lawn care product just makes you feel good.

What to Look For When Buying Pre-Emergent for Your Lawn

The specific factors that you should prioritize when choosing a pre-emergent herbicide are:

Ingredients

The active ingredient(s) in a pre-emergent herbicide determine its efficacy. As such, you should pay attention to the list of ingredients highlighted on a product’s label. Examples include:

• Dithiopyr –  it’s among the most effective ingredients against crabgrass and several common broadleaf weeds. But what I like even more is that it doubles up as a post-emergent herbicide for certain weeds. And, it’s safe to use on ornamental grasses as well.
• Isoxaben – isoxaben works by disrupting the production of an enzyme that’s crucial for photosynthesis. This disruption interferes with the germination of weed seeds, preventing them from going beyond the seed stage. The icing on the cake is the fact that it works selectively. So you don’t have to worry about your turfgrass or crops getting damaged.
• Trifluralin – one other ingredient that’s proven successful at preventing weed growth is trifluralin. It works by inhibiting cell division at the roots. As a result, the roots are unable to grow, bringing the weeds’ growth to an instant halt. Like isoxaben, this is also selective, meaning it’s safe to use around flower beds and vegetable crops.
• Prodiamine – this ingredient also disrupts the weeds’ cell division; thus, preventing the formation of new leaves and stems. An important thing to note about prodiamine is that it has a longer residual period. With other ingredients, their effects last for just a couple of weeks. But this one lingers in the soil for 3 to 4 months, which is both good and bad. It’s great if you’re looking for a foolproof solution and lasting control of crabgrass and other annual weeds. However, it can cause significant delays if you were planning to plant grass seed or other crops, so timing (and planning) really matters.
• Corn gluten – if you’re looking to buy an organic pre-emergent herbicide, this is the most likely ingredient that you’ll find. It’s great at preventing weeds from germinating. The only downside is that it’s a non-selective herbicide. So in the same way that it prevents weed seeds, it can prevent other beneficial seeds from germinating too. Furthermore, it works exclusively as a pre-emergent where it inhibits root formation of germinating plants. So if you have perennial weeds or annual weeds which have already germinated, this won’t touch them.

Selectivity

Another aspect to keep in mind is the herbicide’s selectivity. By this I mean its ability to stop weed growth without harming your lawn.

Selective herbicides target some plants, but not all. These tend to be the best choice for lawn areas because they usually won’t bother your turfgrass and will only target weeds.

Conversely, non-selective herbicides target every living plant. These are the weed killers that will also kill your grass.

Finally, you want to be aware of how pre emergent herbicides will impact any seeding projects you have planned. If you’re hoping to overseed your lawn in the spring. Choose the wrong pre-emergent product, and you’ll block weed seeds and that expensive grass seed you just dropped a few hundred bucks on.

Yikes.

Pre-Emergent Weed Control When Overseeding
If you plan to overseed your lawn at a time of year when you would normally put down pre-emergent, I recommend using this product,* followed 5 weeks later with one of the pre-emergent products listed on this page. This will allow your grass seed to germinate, but blocks crabgrass for up to 6 weeks, buying you (and your new grass) some time.

Ready-to-Use vs Concentrate

One more decision that you’ll have to make is choosing between ready-to-use and concentrate products.

• Ready-to-Use – this herbicide comes ready to use. It doesn’t have to be diluted or mixed with any other solution; hence, saving you time. Some liquid products come ready-to-use, but with pre-emergents, you’re mostly looking at granular products.
• Concentrate – this type of herbicide is meant to be mixed with water in a separate application bottle. In some cases, the manufacturer may recommend adding a surfactant as well (I use and recommend this one from Southern Ag). Using a concentrated pre-emergent is more economical for those with big lawns. Since it has to be diluted with water, you’ll be able to create bulk quantities of solution to cover your lawn; no matter how big. Get a backpack sprayer and you’re good to go.

What to Avoid When Buying Lawn Pre-emergent Herbicide

There have been reports of pre-emergent herbicides failing to work as they’re designed to.

If you experience this, there’s a high chance that you’re making one of these common mistakes:

• Buying at the wrong time – with pre-emergent herbicides, timing is key! If you struggle with summer seeds, then don’t wait until the season starts to buy. Instead, you should buy and apply in early spring before their seeds start to germinate. Similarly, winter weeds are best dealt with in early fall.
• Not identifying the type of weed in your lawn – just because a product is described as a pre-emergent doesn’t mean that it can prevent the growth of every weed species. So it’s important that you first identify the most common weeds in your lawn and buy a herbicide that’s effective against them. For instance, choose a pre-emergent herbicide for crabgrass if you identify that this is a big problem in your yard.
• Failing to consider the form of the pre-emergent – don’t forget to check whether the herbicide is liquid or granular. This is because each one requires a specific technique for application. For liquid pre-emergent products, you’ll need a good backpack sprayer of some sort. On the other hand, granular herbicides are best dispersed with a high-quality fertilizer spreader.

The best pre-emergent herbicides for lawns are able to stop a wide variety of weeds from growing. Hopefully the list provided above will steer you toward the best product for your lawn and application.

But if you’re still undecided, keep scrolling to read detailed information and specifications of each product, along with a list of retailers where you can compare prices to find the best deal.

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Dimension 2EW is among the most popular choices of herbicide for many homeowners, and it’s easy to see why.

Though it comes at a steep price, it’s formulated with a very efficient ingredient, making it worth the price if you’re serious about lawn care. Here’s a more detailed review of it.

Composition

The main thing that sets the Dimension 2EW apart is its active ingredient. The dithiopyr makes up a whopping 24% of the total composition, providing a substantial amount of herbicide to stop weeds in their tracks.

Even better, it works as both a pre-emergent and post-emergent herbicide. However, its efficacy depends on the particular weed species you’re trying to control.

If your lawn is invaded with crabgrass, then you can use the 2EW both for pre- and post-emergence. This product also offers season-long control for weeds, such as foxtail, spurge, goosegrass and bluegrass.

That said, the manufacturer recommends adding a dash of surfactant to boost its post-emergent effectiveness.

A surfactant is a compound that increases the herbicide’s penetration. It allows the solution to stick onto leaves’ surfaces long enough for it to be absorbed by the rest of the plant. I keep a bottle of Southern Ag’s surfactant (Amazon link) on hand for use with both liquid herbicides and liquid fertilizers, and can recommend it.

Rate of applications & Coverage

Another thing that I love about this herbicide is that it’s available in different sizes. This allows you to buy just the amount that covers your lawn. To be specific, it comes in 64-ounce, ½-gallon and 2.5-gallon jugs.

Given how efficient it is, you don’t need to apply a ton of it to see results. Just 0.28 to 0.73 oz. is enough per 1,000 square feet of space. This means that ¾ to 2 pints of the weed killer can cover a whole acre.

Also crucial to point out is that the herbicide doesn’t have any pungent smells and it doesn’t leave any stains either.

Dimension 2EW Specifications

Active ingredient	Dithiopyr
Purpose	Pre-emergent and post-emergent
Form	Granules

My Final Take-Away: Prevent pesky weeds from sprouting on your lawn by applying Dimension 2EW. It’s formulated with dithiopyr, a strong ingredient that provides early post-emergence as well.

Where to Buy Dimension 2EW

You can compare prices and order this online at the following retailers:

• AMAZON
• DO MY OWN

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Anytime you’re buying a herbicide for a large lawn, you have to be particularly cautious.

You don’t want to apply a product that ruins the look of that magnificent lawn that you worked so hard to create.

On that note, Prodiamine 65WDG is the perfect pre-emergent herbicide for big yards. Here’s a more detailed look at its features.

Composition

The name says it all. Essentially, the active ingredient in this herbicide is Prodiamine, and it accounts for at least 65%.

What I like about this compound is that it works selectively. It can kill weeds without causing any harm to most lawn grasses. So whether your lawn comprises Fescue, St. Augustine or Bermudagrass, you can rest easy knowing that it won’t suffer any damage when applied properly.

Better yet, this product prevents the growth of a wide array of weeds. Examples include:

• Bluegrass
• Barnyardgrass
• Carpetweed-04
• Chickweed
• Crabgrass (large and smooth)
• Crowfootgrass
• Cup grass
• Foxtails
• Goosegrass
• Henbit
• Itchgrass

Application

The Prodiamine 65 offers several benefits when it comes to application. For starters, it comes in the form of wettable, dispersible granules; hence, the ‘wdg’ in the title.

What this means is that the granules dissolve very fast in water, which makes for an easy application. And (if you store it properly) it will last you for years because you can effectively mix your own “Barricade” – my pick for the top granular pre emergent on the market.

To create the solution, start by filling your spray tank a quarter way full with water or any other fluid fertilizer. Next, add the herbicide, and shake vigorously so that all the contents are well-combined. Now all that’s left to do is to apply it to your lawn.

Another perk of this pre-emergent herbicide is its flexibility. Unlike other products that can only be applied in a specific season, this one can be applied in both spring or fall.

It can also be applied alongside fertilizers and iron solutions. In fact, if you want to feed your lawn, you can mix the herbicide with a fluid fertilizer instead of water.

Prodiamine 65 WDG Pre-Emergent Specifications

Active ingredient	Prodiamine
Purpose	Pre-emergent
Form	Granules

My Final Take-Away: If you have a big lawn, the Prodiamine 65 WDG is an excellent weed-preventer. The herbicide comes in wettable granules, which dissolve easily in water. This helps you create a considerable amount of solution to cover your entire yard.

Where to Buy Prodiamine 65WDG

You can compare prices and order this online at the following retailers:

• AMAZON
• DO MY OWN
• WALMART

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Have you been searching for an alternative to chemical-filled pre-emergent herbicides? If you have, Espoma Organic Weed Preventer is just what you need. Here’s what you can expect from this all-natural herbicide.

Composition

As you might have guessed, Espoma’s core ingredient – corn gluten meal – is its biggest selling point. It’s an organic element, which makes this herbicide safe for pets, humans and the environment.

Even better is the fact that this element pulls double duty as a weed preventer and fertilizer. So not only does it stop weeds from sprouting but it also nourishes your lawn.

This explains why the product is described as having an NPK ratio of 9-0-0, meaning it contains at least 9% nitrogen.

As a weed preventer, it can be used against multiple weeds, ranging from crabgrass to bluegrass, quackgrass and dandelions.

Application

Espoma Organic Herbicide is only available in a 25-pound bag. It comes in the form of granules, meaning you’ll need either a broadcast or drop spreader for application.

Also crucial to note is that the application rates differ based on your intent. If you’re applying it with the aim of preventing weeds, the recommended rate is 2 lbs. per 100 sq.ft. You can then reapply after 4 to 6 weeks depending on the results you get.

Conversely, if you’re applying Espoma as a fertilizer, the recommended rate is 10 lbs. per 1,000 sq.ft.

Regardless of the intent, be sure to water your lawn lightly after application. This allows the product’s nutrients to be absorbed better into the soil.

It’s very crucial that you apply Espoma weed preventer at the right time, that is, before the weeds emerge.

If you apply it when the weed seeds have already germinated, it won’t kill them. In fact, there have been cases of the herbicide causing the weeds to become greener- the complete opposite of what you want.

Espoma Organic Weed Preventer Specifications

Active ingredient	Corn gluten meal
Purpose	Pre-emergent
Form	Granules

My Final Take-Away: For natural weed control, the Espoma Organic Weed Preventer is the ultimate remedy. It’s made purely from organic ingredients, making it safe for the environment and people.

Where to Buy Espoma Organic Weed Preventer

You can compare prices and order this online at the following retailers:

• ACE HARDWARE
• AMAZON
• DO MY OWN
• WALMART

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Unlike their liquid counterparts, granular herbicides barely need any mixing, which significantly simplifies their application.

And if you already have a fertilizer spreader, you can use that to spread your granular herbicide. If you enjoy these perks, then consider the Andersons Barricade, often ranked as the best granular pre-emergent herbicide, and a product I highly recommend.

Composition

The active ingredient in the Andersons Barricade is prodiamine. And although it accounts for just a small proportion (0.48%), it’s incredibly effective.

It works by creating a barrier on the surface of the soil. This lingers for several weeks, “barricading” or preventing weed seeds from emerging.

That said, Andersons is quick to note that it can have a negative effect on grass seeds too. Essentially, it can prevent grass seed from germinating if it’s applied too early on. The manufacturer thus recommends waiting at least two months to apply Barricade after seeding.

Application

To get the best results, it’s important that you time your herbicide application correctly.

If you’re looking to prevent summer weeds, then apply it in early spring; preferably when the soil temperature is about 55°. You can also apply it in early fall to keep winter weeds like bluegrass from growing.

Since this pre-emergent herbicide comes in granular form, it also needs to be watered in. Time your application right before a light rainfall. Alternatively, irrigate or water your lawn shortly after the treatment.

This product touts Anderson’s proprietary Dispersible Granular (DG) technology. This allows every granule to break down into dozens of micro particles as soon as it comes into contact with water.

Moreover, this technology allows the granules to penetrate deep into the soil even if your lawn is covered in thatch.

I was also impressed to learn that the herbicide comes in two different sizes: 18- and 50-pound bags. This allows you to buy just the right amount for your lawn; hence, avoid wastage.

However, this product also comes with dozens of instructions on how to use it. Though helpful, a lot of buyers have found the details overwhelming and confusing. 

The Andersons Barricade Specifications

Active ingredient	Prodiamine
Purpose	Pre-emergent
Form	Granules

My Final Take-Away: If you’re more comfortable with applying granular products to your lawn and aren’t ready to take the leap to liquid pre-emergent products, choose The Andersons Barricade. It’s the perfect solution for most homeowners. It’s formulated with Prodiamine, an ingredient that effectively stops the germination of weed seeds.

Where to Buy The Andersons Barricade

You can compare prices and order this online at the following retailers:

• THE ANDERSONS WEBSITE (Save 10% with code LAWNCHICK)
• AMAZON
• DO MY OWN
• WALMART

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Looking for a way to nourish your lawn while simultaneously keeping those pesky weeds out? If you are, the Andersons Premium Crabgrass Preventer plus Lawn Food is a fantastic choice.

It’s a pre-emergent herbicide that doubles up as a fertilizer. Here’s a more detailed review of it.

Composition

The biggest selling point of this pre-emergent is its ability to nourish your lawn. With an NPK ratio of 26:0:6, it provides a healthy serving of nitrogen and potassium.

At the same time, its core ingredient is dimension. This does an exceptional job of keeping grass and broadleaf weeds at bay. And the best part is that it provides protection for a whopping 4 months.

Application

As with other pre-emergents, the Premium Crabgrass Preventer is best applied in spring. This way, it’s able to tackle weeds before they emerge. It can also be applied in fall if your lawn tends to get more weeds in winter.

That said, there are a couple of things you’ll want to keep in mind before its application.

For starters, Andersons recommends mowing your lawn prior to treatment. This allows the herbicide to be absorbed more efficiently.

For the same reason, be sure to water in the product within 14 days of application. Finally, the manufacturer warns against using the herbicide in recently seeded lawns.

I also like that this fertilizer/pre-emergent comes in a generous bag. It’s packaged in a 17-pound bag that’s enough to cover an area of 6,000 sq.ft.

The Andersons Premium Crabgrass Preventer Specifications

Active ingredient	Dimension
Purpose	Pre-emergent
Form	Granules

My Final Take-Away: One way to save money on lawn care is by investing in multipurpose products, and for a pre-emergent take on the weed-and-feed products you may have used in the past, choose The Andersons Premium Crabgrass Preventer plus 26-0-6 Lawn Food. In addition to preventing weed growth, it provides your lawn with a modest dose of nitrogen and potassium.

Where to Buy The Andersons Premium Crabgrass Preventer Plus Lawn Food

You can compare prices and order this online at the following retailers:

• THE ANDERSONS WEBSITE (Save 10% with code LAWNCHICK)
• AMAZON
• WALMART

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While it’s not a name you’ll hear discussed on many blogs and YouTube channels about lawn care, Bonide’s DuraTurf Weed Preventer is a very solid option that uses Dimension – the same herbicide in my pick for best lawn pre-emergent overall.

One thing I like about it is that it offers the efficacy of Dimension while providing homeowners with the ease-of-use of a granular product, and it is priced very competitively.

So if you have a very big lawn that you want to treat, you can buy several bags without putting a dent in your pocket.

Here’s everything you need to know about this under-rated pre-emergent lawn herbicide from Bonide.

Composition

The active ingredient in this pre-emergent is dithiopyr, and it’s easy to see why.

For one, it works on a wide range of weeds and not just crabgrass. The main weeds that are listed are dallisgrass, bluegrass, barnyard grass, chickweed, henbit, spurge, oxalis, foxtail and goosegrass.

Another reason why dithiopyr remains a favorite is the fact that it provides early post-emergence. However, this only applies to crabgrass, whereby it kills and wards off the established weeds for up to a month.

Application

To make the most of this pre-emergent, there are a few points you should consider.

First off, it can only be applied on well-established lawns. If your lawn has just recently been laid, wait a few weeks or until the turfgrass develops a strong root system. On the same note, it’s not advisable to apply it on a distressed or struggling lawn.

When it comes down to the application process, the recommended rate is 4.3 pounds for every 1,000 sq.ft. The entire bag contains 9.5 lbs., giving you enough to treat a 5,000 sq.ft lawn.

Bonide DuraTurf Weed Preventer Specifications

Active ingredient	Dithiopyr
Purpose	Pre-emergent and post-emergent
Form	Granules

My Final Take-Away: This exemplary weed preventer boasts a dual-action formula that provides pre- and post-emergence control. Once you apply Bonide DuraTurf, you’re guaranteed that your lawn will remain weed-free for at least four weeks.

Where to Buy Bonide’s DuraTurf Weed Preventer

You can compare prices and order this online at the following retailers:

• ACE HARDWARE
• AMAZON
• DO MY OWN
• WALMART

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Are you the kind of person who prefers to use just one herbicide throughout the season?

If you are, then you’ll want one that’s easily accessible like Scotts Halts Crabgrass & Weed Preventer. Here’s a detailed look at its features:

Composition

One thing that makes this pre-emergent unique is its core ingredient.

The pendimethalin that makes up about 1.71% of its composition, isn’t as popular as dithiopyr or prodiamine but it’s equally effective.

It works by impeding cell division and elongation, both of which prevent further formation of the weeds’ roots and shoots. Some of the weeds that it helps to control are:

• Crabgrass
• Barnyard grass
• Spurge
• Foxtail
• Goosegrass
• Oxalis

Another feature that I like entails its rate of effectiveness. Once you apply it in early spring, it keeps out weeds throughout the entire season. And if you want, you can apply it once more in early fall to prevent winter weeds.

Application

The Scotts Halts Weed Preventer is available in one of two sizes. So depending on the size of your lawn, you can buy the 10.06-pound or the 20.12-pound bags.

The first option treats an area of 5,000 sq.ft. while the latter treats twice that size. 

Like the majority of pre-emergents in our review, this one also comes in granules. So all you’ll need is a spreader to disperse it evenly. Its only drawback is that it can’t be used on lawns that contain dichondra or bentgrass.

Scotts Halts Crabgrass & Weed Preventer Specifications

Active ingredient	Pendimethalin
Purpose	Pre-emergent
Form	Granules

My Final Take-Away: If you don’t want to struggle looking for a pre-emergent herbicide, consider Scotts Halts Weed Preventer. It’s sold by nearly all major retailers, making it easy to find. And, it works against several weed species.

Where to Buy Scotts Halts Crabgrass & Weed Preventer

You can compare prices and order this online at the following retailers:

• AMAZON
• HOME DEPOT
• DO MY OWN
• WALMART
• TRACTOR SUPPLY CO.

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Maintaining a lawn can be expensive, especially when you consider all the different products that you have to buy.

Fortunately, Spectracide Weed Stop typically costs less than $25 and offers 5 months of weed prevention, helping you save a few bucks and stretch your investment in lawn weed control. Despite its low price, it has some pretty impressive features that I’ve highlighted below.

Composition

The active ingredient in this pre-emergent is 2,4-Dichlorophenoxyacetic acid, which is usually shortened to 2,4-D.

This ingredient works by causing proliferated weed growth. Essentially, it causes the plant cells to increase uncontrollably to the point the weeds can’t keep up. So they eventually die.

But what impresses me the most is that 2,4-D works selectively. It prevents weeds and other undesirable grasses from growing without affecting the growth of beneficial crops.

According to the manufacturer, it eliminates over 200 weed species. This includes common culprits like chickweed, dandelion, thistle, crabgrass and clover. 

Application

While its affordability is a big selling point, it comes at the expense of quantity. Put simply; the Spectracide Weed Stop is best-suited for small-size lawns not exceeding 3,000 sq.ft.

On a more positive note, this herbicide only takes one treatment to work. So you don’t have to worry about spending money on multiple applications.

When it comes down to the nitty gritty, this granular fertilizer can be applied using either a drop or rotary spreader. Whichever equipment you use, the recommended application rate is 3.6 lbs. per 1,000 square feet.

Sounds easy, right? Well, there are a few areas where Spectracide’s application differs from other granular herbicides.

For one, it should only be applied to a lawn that’s wet from either dew or a light rainfall. Scattering the granules on a dry lawn doesn’t yield the best results. Secondly, avoid watering your lawn for the next 24 hours following an application.

Spectracide Weed Stop Specifications

Active ingredient	2,4-Dichlorophenoxyacetic acid
Purpose	Pre-emergent
Form	Granules

My Final Take-Away: If you’re on a shoestring budget, Spectracide Weed Stop fits the bill, literally. It’s affordable and doesn’t compromise on quality.

Where to Buy Spectracide Weed Stop

You can compare prices and order this online at the following retailers:

• AMAZON
• HOME DEPOT
• WALMART

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If you’re like many homeowners shopping for pre-emergent herbicides, you might still have some questions.

Below I’ll try to provide some more information about choosing and using pre-emergent herbicides on your lawn.

I’ll also help you out by explaining some tips, tricks, and things to consider when buying the best pre-emergent for your lawn.

If you’re still on the fence, please explore my site. I have hundreds of in-depth articles on a range of topics about yard maintenance and lawn care, and I expect that you might find one that addresses your specific question or concern.

For now, here’s some further reading about pre-emergent products that might help as you make your final purchase decision:

Do you have to water in pre-emergent herbicide?

It really varies from one product to the next, but for some you don’t want to water the lawn immediately after application.

The Spectracide product is a good example. Unlike other granular herbicides that require watering in, this one requires that you wait at least 24 hours.

I always recommend carefully reading the instructions from the manufacturer, paying attention to the weather, and following the guidance on the package for best results.

Why should I use pre-emergent herbicide?

A pre-emergent herbicide gives you a much-needed head start. It lets you stop weeds from invading your lawn before they have a chance to grow into well-established plants.

It also helps the turfgrass you desire in your lawn to thrive because it reduces pressure and competition for nutrients from annual weeds.

This allows your established lawn grass to spread out, fill-in, and thrive in ways it could not if it was competing with weeds.

This, in turn, helps to create a dense canopy of desirable turfgrass which will help keep weeds out of your lawn in the future.

When should I apply pre-emergent herbicide?

The ideal time to apply a pre-emergent herbicide depends on two things, namely, the weed species and ground temperature.

To control summer weeds like crabgrass, sandbur and foxtail, apply the pre-emergent in early spring. These weeds will begin to germinate when your soil temperature hits 55 degrees. For many people, the perfect time for your pre-emergent application is when forsythia start to bloom.

For weeds that thrive in cooler temperatures – like chickweed and henbit – prevent their growth with an early fall treatment – you can apply it at the same time you apply your last summer or first fall fertilizer appliaction.

Still, determining the best time to apply this herbicide might be a little difficult. As I explain in my free lawn care cheat-sheet, the easiest way to determine this is to check the soil temperature.

For spring treatments, wait until the soil temperature is about 55° for a minimum of 48 hours.

How long after applying a pre-emergent can you plant grass seed?

Most pre-emergent herbicides prevent just about every seed from germinating, so you won’t be able to seed your lawn for quite a while after laying down pre-emergent herbicide in your yard.

If you plan to do an overseeding project in the spring, you can still do it, but you’ll want to use a combination of this product (which blocks weeds while allowing grass seed to germinate and grow) when you spread your seed, followed up 5-6 weeks later with an application of Dimension, which kills young crabgrass that may be starting to grow in addition to providing pre-emergent protection for the rest of the season.

All of the pre-emergent products included on this list will say specifically on the package their duration (or how long they last). For many it is somewhere between 3-5 months.

So it’s important that you check the individual ingredients in each herbicide and the duration they last. Many will prevent grass seed from growing.

How often should you apply a pre-emergent herbicide?

The frequency of application depends on the condition of your lawn.

Typically, a single treatment of a pre-emergent lasts anywhere from 3 to 5 months. This means that you can apply it just once a year in the spring and get a good outcome if you have a dense, healthy lawn.

Once your turf gets a head start, the grass helps to create a dense cover that deprives late-season crabgrass from the sunlight it needs to germinate once your pre-emergent fades.

However, if your lawn has a very thin layer of grass or patchy grass, you may want to apply a second application a few weeks prior to the first one fading.

How much rainfall you get impacts the duration and longevity of the protection offered by pre-emergent herbicides. Heavy rains means it won’t last quite as long.

Can you spray pre-emergent on newly seeded grass?

No, you cannot. If you’ve just planted grass seeds on your lawn, consider waiting for at least 14 days (longer if possible – you want all of your seed to germinate first) before you apply the pre-emergent.

Applying some of these herbicides too early after seeding can kill the grass seed and seedlings as well, so you really want to apply it to established lawns.

As I mentioned above – if you’re seeding in the spring use this product at the time you plant your seed, and then about a month after your grass germinates, use a pre-emergent or a weed and feed product designed to control Crabgrass and other weeds you are dealing with.

Are pre-emergent herbicides safe?

Pre-emergent herbicides are safe to use on most lawns and won’t harm your lawn grass if applied at the manufacturer’s specified rate. The vast majority of them are designed to target weed seeds. This means that they rarely cause harm to fully-established plants.

That said, these are herbicides and it’s important to protect your own health and the health of your family, pets, and neighbors.

It’s important that you use them as directed. Here are a few safety tips that you should adhere to:

• Wear protective gear – whether you’re dealing with organic or synthetic herbicides, you should always don in protective gear. This entails gloves, long-sleeved shirt/blouse, eye protection, long pants and a dust mask.
• Choose a calm day for application – this is particularly crucial if you’re dealing with a liquid herbicide. A strong breeze can easily blow the sprayed product away, compromising its coverage and efficiency.
• Wash up after a treatment – regardless of how careful you are, part of the product can inadvertently end up on your clothing or skin. So to minimize the risk of toxicity, ensure you wash up after applying the herbicide.
• Clean the tools you use to apply the pre-emergent – this helps to avoid cross-contamination, especially if you use the same tools to apply fertilizer and other lawn care products.
• Avoid spreading the herbicide near a water body– the pre-emergent ingredients can easily end up in waterways and destroy aquatic life.
• Follow the instructions provided for mixing – if the herbicide is meant to be mixed with water or a surfactant, stick to the ratios and guidelines indicated on the label.

If you mix any herbicide (including pre-emergent) and have leftovers, don’t just dump them out. Google household hazardous waste disposal near me and you’ll find a list of places which are equipped to properly and safely dispose of any herbicides you need to get rid of.