Pre Emergent – Pros, Cons, and How To Use It Most Effectively In Your Landscaping

Weeds. The bane of any gardeners’ existence.

Just because summer is coming to a close doesn’t mean gardening season is over. In fact, it may be the perfect time to protect your outside sanctuary from those pesky and sometimes garden-destroying weeds, and this is where pre emergent weed control comes in.

But in today’s world, there are so many different types of pre emergent, from organic weed killers to chemical herbicides and many that fall somewhere in between. Which type and product is best for you?

If you’re new to gardening, or even if you’re a pro, you may find yourself scratching your head and wondering how pre emergence herbicides work, which brands work most effectively, and whether or not there is a secret to applying pre emergent in order to best protect your garden.

We are going to answer all that and more. Join us today as we learn about the pros and cons of pre emergent and how to use it most effectively in your landscaping.

What Is Pre Emergent And How Does It Work?

Pic 1 a home with a beautiful garden
Pre emergent can help prevent the new growth of weeds and help keep your garden looking pristine.

Pre emergent is an herbicide that is designed to protect lawns and gardens from emerging weeds. Many people wrongly assume that pre emergent will kill weed seeds along with old, pre-existing weeds, but this isn’t true.

When applied correctly, pre emergent works as a preventative after the germination period of a weed seedling to stop the development of said weed. However, it will not harm or kill old existing weeds, which is why many gardeners must use both a post emergent and a pre emergent together.

The below video explains this in a bit more detail. 

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It’s never too early to put down a good pre emergent to protect your lawn and garden. In fact, you can put pre emergent down almost anytime of the year depending on where you live. But we’ll cover that further down.

For now, let’s talk more about how pre emergent works to prevent future weeds in your garden and landscaping.

Pre emergent herbicide is a chemical herbicide that is un-soluble. This keeps it at the soil’s surface, where most weed seedlings tend to germinate. Once applied, microbes in the soil break down the chemical in the pre emergent, allowing it to create a protective barrier over your lawn’s soil to prevent future weeds from germinating and popping up.

The way pre emergent works has to do with a combination of timing, soil temperature, and application.

Most experts agree that applying pre emergent earlier to your lawn is better, as it gives the chemical a better chance at eradicating the weed once it begins to germinate from the seed. If you apply pre emergent to your lawn too late, the pre emergent may not be effective at all as it is not designed to harm already existing weeds.

Pre emergent is an important part of gardening and landscaping, especially when it comes to weed control. That said, in an age where many gardeners are turning to organic options, is this chemical weed deterrent really the best option?

Let’s find out.

Is Pre Emergent Safe? The Pros and Cons of Using A Chemical-Based Pre Emergent

Pic 2 two little girls in a garden
Children and pets should stay off of the lawn and out of the garden for 24 to 48 hours after chemical pre emergent is applied.

Yes, it’s true that pre emergent is a chemical, but studies have shown that it is relatively safe for people, pets and even the environment when applied correctly. That said, there are laws and regulations in many regions when it comes to using chemicals like pesticides and herbicides in yards and gardens. We must be careful and use these chemicals responsibly to ensure they are not only effective, but safe.

Let’s take a look at some of the pros and cons of using a chemical pre emergent in your garden or landscaping.

Pros To Using Pre Emergent 

  • Pre Emergent Comes In Different Types Depending On Your Needs
  • Herbicides Can Be Used To Cover A Large Surface Area At Once
  • Pre Emergent Herbicides Can Control A Variety of Weeds In A Single Lawn
  • Pre Emergent Is Generally Safe for People, Pets and the Environment When used As Directed
  • Many Pre Emergent Herbicides Are Long Lasting
  • Pre Emergents Are An Easy, Inexpensive and Effective Way To Control Weed Growth

Cons To Using Pre Emergent

  • Children and Pets Should Stay Off The Lawn Immediately After Application of An Herbicide for 24 to 48 Hours
  • Timing For Proper Application Of Pre Emergent Can Be Complicated
  • Pre Emergent Herbicides Are Chemicals And Do Come With Some Risk
  • If Used Incorrectly, Pre Emergent Can Cause Harm To Ornamental Plants and Landscaping
  • Pre Emergent Does Not Always Control Every Type Of Weed

Different Types Of Pre Emergent – Which Weeds Are You After?

Pic 3 a dandilion
Different weeds may require treatment from a certain type and certain chemical herbicide.

There are currently five types of pre emergent herbicides. These types include:


  • Broad Spectrum Herbicide

Broad spectrum herbicides are designed to work on a large variety of weeds and cover a large space. This type of herbicide is ideal for those looking to protect their entire lawns from weeds.


  • Selective Herbicide

If you have a specific type of weed you are dealing with, you may consider or need a selective herbicide. This type of pre emergent will ensure your particular weeds are dealt with.


  • Contact Herbicide

Contact herbicides are ideal for those with patches of weeds in their yard or garden and who do not wish to use a broad spectrum herbicide and would prefer to specifically target a single area.


  • Systemic Herbicide

For many people who are wary of using pre emergents or herbicides in their garden (especially if you prefer organic gardening) but need to use a pre emergent chemical to destroy a particular weed, systemic herbicide may be right for you. This type of herbicide specifically targets one weed and only affects that weed’s circulation system. Infact, it can even be injected in said weed so as not to affect the soil or surrounding plant life.


  • Residual Herbicide

Residual herbicides are some of the most common and easiest to use. They are applied directly to the soil of the lawn, are long-lasting, and are designed to control weed seedlings that are in the process of germinating.

So, which type of pre emergent herbicide is right for you? Well, that depends.

Different types of pre emergent contain different chemicals based on the types of weeds an individual hopes to eradicate, but some of the most common chemicals found in pre emergent include:


Prodiamine is possibly the most popular active chemical in most pre emergent products. It covers a wide range of weeds and has been found to be relatively safe for people, pets and the environment when applied correctly.

Some common weeds Prodiamine is most effective against include:

  • Crabgrass
  • Bluegrass
  • Spurge
  • Witchgrass
  • Knotweed
  • Henbit
  • Chickweed
  • Foxtail
  • Goosegrass
  • + 31 More Grasses and Broadleaf Weeds


This chemical ingredient works primarily on grassy and broadleaf weeds, and may even be effective against already sprouted young weeds as well, but only if it’s applied heavily. It is a long lasting herbicide chemical that can continue protecting your lawn for up to four months after application.

Some weeds Dithiopyr is most effective against include:

  • Crabgrass
  • Goosegrass
  • Bluegrass
  • Chickweed
  • Spurge
  • + 40 More Grassy and Broadleaf Weeds

Oryzalin (AKA Surflan)

Oryzalin, also known as Surflan, is another broadleaf weed killer that works best in spring and fall. It is most popular for its effectiveness against spruge and it’s success with weed control in turfgrass. This chemical is an active ingredient in several well-known pre emergent brands, which we will discuss in more detail below.

Some weeds Oryzalin is most effective against include:

  • Bittercress
  • Chickweed
  • Spurge
  • Pigweed
  • Yellow Woodsorrel
  • Velvetleaf
  • Smartweed
  • Velvetleaf
  • Crabgrass
  • Ryegrass
  • Johnsongrass
  • Barnyardgrass
  • + Many More Annual Weeds and Grasses

How To Use Pre Emergent Most Effectively In Your Landscaping

Pic 4 a gardening shovel
It’s important to read instructions and apply your chosen pre emergent properly. 

The most important factor to consider when applying pre emergent to your lawn is temperature. Weather that is hotter than 90 degrees tends to disrupt the effectiveness of pre emergent, so experts recommend applying it to your lawn when the weather is at least 80 degrees or cooler.

Ideally, pre emergent works best in soil temperatures that are around 50 to 55 degrees. This will vary depending on your region and which climate you live in, so keep that in mind.

Most experts recommend applying pre emergent twice to lawns as different weeds germinate at different times. The first application is generally around when the soil is warmer (50 to 55 degrees) which is typically spring or summer for many of us. The second application of pre emergent would be when the soil is cooler, during late fall or early winter.

Unfortunately, if you get your application times incorrect, or if you apply too much or too little pre emergent, you could wind up with adverse effects.

For example, if you apply pre emergent to late or too early, it may not work to stop the sprouts during germination. On the other hand, if you apply too much, even if you apply it at the correct time, you could risk causing damage to your lawn or ornamental plants.

You also must have a good idea of which type of weeds you’re after, as we mentioned above, to ensure you purchase the correct pre emergent herbicide for you.

The Top Chemical Pre Emergent Products, According To Experts

Pic 5 a person watering their garden
Some pre-emergence products work best with water while others activate in the soil on their own. 

Just as there are different types of pre emergent herbicides, there are also different brands. Not all brands are made the same and some are designed for smaller gardens while others will cover entire green belts. The type of pre emergent that is best for you will depend on three factors:

  • Your Region
  • The Weeds You Are After
  • And The Size Of Your Yard

Now, let’s take a look at some of the best pre emergent products according to experts below.

Scotts WeedEx Pre Emergent

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If crabgrass is your arch enemy, then Scotts WeedEx may be right for you. It specifically targets and stops crabgrass from spreading when applied correctly in the early spring, but it can also prevent other weeds when applied in fall including bluegrass, chickweed, foxtail, spurge, oxalis and henbit.

You can order it specified for your particular region and it comes in two size options depending on your needs.

Roundup Landscape Weed Preventer

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Another pre emergent we like is made by Roundup, which is a popular gardening and weed prevention brand we trust. This weed preventer covers a wide surface area and creates a barrier on top of the soil to prevent future weeds from sprouting.

When applied correctly, it can last for up to six months and will prevent a number of weeds and grasses. Best of all, it won’t damage or kill your desirable plants.

The Andersons Pro Turf Barricade

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If you’re looking for an easy application pre emergent, you’ll like The Andersons Pro Turf Barricade. This herbicide comes as granules that are easy to spread in your lawn and can cover up to 5,800 square feet.

Like most pre emergent products on this list, this product should be applied to your lawn once in early spring and then again in the fall. With this product in particular, it is important to carefully read the instructions as it works best with water.

In order for the herbicide to become active and stop the weeds from sprouting, you must either apply it before rain or use it in conjunction with irrigation.

Green Light Amaze Grass and Weed Preventer

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Green Light Amaze pre emergent covers up to 4,000 square feet and is designed to be used in already established yards and gardens. It works to control and prevent weeds from sprouting in flower beds, vegetable gardens, lawns, and below shrubs and trees.

When properly applied, this pre emergent weed preventer will last all season and can help prevent grasses and weeds like knotweed, henbit, yellow woodsorrel, foxtail, chickweed, blue grass, crabgrass and more.

Scotts Halts Crabgrass and Grassy Weed Preventer

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This is another pre emergent herbicide by Scotts, but this one is particularly designed to prevent crabgrass. Of course, like most pre-emergents, it can also prevent weeds like chickweed, henbit, bluegrass, and other winter weeds when applied correctly.

This product is unique in that it won’t be affected by extreme weather conditions including freezes or snow. It can also help prevent the growth of moss.

Preen Garden Weed Preventer

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If you’re looking for a pre emergent that covers a decent surface area while also helping to improve the growth of ornamental plants, you’ll want to take a look at Preen Garden weed prevention. This is a plant food PLUS pre emergent product that prevents the growth of weeds while fertilizing your lawn and feeding your garden plants.

It can cover up to 2,560 square feet but can be ordered in different sizes depending on your needs. It also comes in a bucket order as opposed to a bag and includes a scoop for easier application.

Once applied, it works for up to three months.

Quali-Pro Prodiamine

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Last on our list is a generic pre emergent that contains the most popular active ingredient, Prodiamine. This pre emergent herbicide works to prevent the growth of new weeds like crabgrass, foxtail, goosegrass, chickweed, bluegrass, henbit, knotweed, and other broadleaf weeds and grasses.

It should be applied once in the spring and again in fall to keep your garden and yard protected from weeds all year long.

Is Organic Pre Emergent Even A Thing?

Pic 6 a father and daughter gardening
Many people prefer to use organic pre emergent alternatives that are safer for people, pets and the environment. 

If you’re concerned about using pre emergent herbicides on your lawn or garden, you’re in luck. There are some organic weed control options you can use in place of chemical pre emergent that should work effectively.

In fact, one of the most popular alternatives to a chemical herbicide is corn gluten meal. This corn by-product can be used in a similar way to chemical pre emergent herbicides, as it covers a large surface area and has been shown to disrupt weeds in their germination period and prevent them from spreading.

However, if not applied correctly or if applied too late, corn gluten meal can act as a fertilizer for weeds, further enabling their growth instead.

Like corn gluten meal, other organic pre emergents also have their pros and cons, and they may not work as well as chemical herbicides. Furthermore, commercial organic pre emergent alternatives may be costlier and require more maintenance when it comes to application.

If you still feel you would like to consider some organic options in place of using a pre emergent herbicide, we have you covered. We have listed some of the best chemical-free weed control options for you to take a look at below.

Espoma Organic Weed Preventer

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We already know corn gluten meal works well as a chemical herbicide alternative, but if you’re not sure how to get your hands on it, you can simply purchase it already packaged. The above order is specifically designed for weed control in yards and gardens and, as it is made with corn gluten meal and is chemical free, it is perfectly safe to use in lawns where children and pets play.

Like chemical pre emergent, it should be applied twice a year during spring and fall, and can help prevent common and problematic weeds from sprouting like crabgrass, dandelions and more.

Safer Brand Weed Prevention

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Another chemical pre emergent alternative is made by Safer Brand. This is an organic pre emergent option that is again made with corn gluten meal. It is completely natural and safe to use in lawns where kiddos and pets play. It can also help control a number of common weeds and will be safe for ornamental plants like roses, flowers and flower beds, trees, veggies and more.

The above order can also be used as a lawn fertilizer when applied correctly, and comes in a pellet form for easy and even distribution on your lawn.

OrganicMatters Natural Weed Killer Spray

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Though not necessarily an organic pre emergent, this organic weed spray can be used in conjunction with the corn gluten meal pre emergent products above to kill pre existing weeds. Remember, even chemical pre emergent products do not kill weeds that have already sprouted, and organic pre emergent products listed above are no different.

This organic weed killer spray comes with a nozzle to make targeted application easier, and it is made with natural ingredients that are safe for people, pets and the environment. Best of all, it works quickly and is able to kill weeds in under 24 hours.

Is Pre Emergent Right For Your Landscaping Needs?

Pic 7 a father and son gardening
Picking the right weed killer and yard protector for you will depend on your goals, but you do have options. 

All gardeners have to contend with weeds, but that doesn’t mean pre emergent herbicides are right for everyone. Using chemicals in your garden can be concerning, and always come with their list of pros and cons.

That said, weeds can also cause major damage to landscaping and ornamental flowers, and can even get you in trouble by your HOA if they get out of control.

Luckily, you do have options when it comes to weed control, whether you choose to use a pre emergent, post emergent, organic weed control option, or preventative. The important thing is that you do your research and understand these options so you are able to choose the weed solution that works best for you and your yard.

Along with using a good pre-emergent, (if that’s what you choose to do) you can also practice some good preventative measures to help keep weeds at bay. Take a look.

Use Newspaper or A Shower Curtain

Many organic gardeners find that using newspaper or a shower curtain is an effective way to kill weeds and prevent new weeds from sprouting. Of course, this may not be the most attractive option of weed control, but it is a natural one and works especially well for those on a budget.

To use this method, simply cover the weed surface area with these above items to block sunlight from the weeds. To make this option less of an eyesore, you can strategically place these items in gardens or yards and then cover them with mulch.


Vinegar is a great spot treatment for weeds that have already sprouted. However, vinegar will also kill ornamental plants and lawns, so cover the plants you want to protect before you use vinegar on any weeds.

You can pour vinegar into a spray bottle and spray it directly on the weeds that are driving you crazy. It works best on young weeds, though it has not been found effective against waxy weeds and leaves like mature thistle.

Vodka And Dish Soap

You can make your own homemade vodka and dish soap weed killer by adding 1 ounce of vodka with 2 cups of water. Drop in 3 to 5 drops of liquid dish soap and mix the solution in a spray bottle.

Like when using vinegar, it’s important to cover any plants you wish to protect. Vodka is very drying, and will work by dehydrating and killing the targeted weeds. It works best on weeds that thrive in sunlight, so we suggest you target those weeds specifically.

Boiling Water

Boiling water is an excellent way to inexpensively and effectively kill problematic weeds on contact. Simply (and carefully) pour boiling water on the weeds you wish to kill. It will work immediately on the weeds without harming neighboring plants.

However, you should avoid using this trick in lawns. The boiling water may kill the weeds cropping up in your grass but it will also potentially leave dead spots in the surrounding areas where it is poured.

So, what do you think about using a chemical pre emergent vs an organic pre emergent? Which option above seemed right for you? We would love to hear your thoughts so drop us a line in the comment section below.

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