Types of Pre-Emergent Herbicides

Tall weeds growing above grass in a yard

Want to keep crabgrass from making you crabby or nip other weeds in the bud before they sprout? Then pre-emergent herbicides are your best defense.

With various types of pre-emergent herbicides available, you’ll want to narrow down your choices according to your needs. Granular or liquid, organic or synthetic, and selective (targeting a specific weed) or non-selective (deterring all sorts of weeds), all varieties serve a purpose you may find useful in your yard. 

To help you pinpoint the right type for your needs, we go down the list and provide valuable information about each option.

What is pre-emergent herbicide?

Many types of weeds lurk in our yards, just waiting for a chance to sprout and wreak havoc. They steal nutrients and water from intended plants, are a pain to remove, and can cause allergic reactions. 

Luckily, you can nip your weed problem in the bud by applying pre-emergent herbicide. It inhibits seed cell division, root development, and enzymes critical to overall weed growth. Pre-emergent weed control creates a chemical barrier in the top layer of soil and coats the weed seeds to prevent them from growing roots. 

Pre-emergent herbicides can be selective or non-selective.

  • Selective herbicides target only specific weeds, so they’re safe to use in areas with other plants and grasses. If only one type of weed grows in your yard — or a few — look for a pre-emergent herbicide that can block that weed from growing. 
  • Non-selective herbicides kill everything they touch (weeds, plants, and grasses), so we recommend using a steady hand when applying a non-selective herbicide. Typically, homeowners choose non-selective herbicides when targeting a localized area like a driveway. 

Before weed seed germination, incorporate your weed preventer of choice into the soil via irrigation. Alternatively, spread the herbicide and wait for rainfall.

Types of pre-emergent herbicides

Liquid pre-emergent herbicides

Man using liquid fertilizer, connected to his hose, for use on his grass

Liquid pre-emergent herbicides are easier and quicker to apply than granular pre-emergents. These herbicide applications are recommended for full coverage over a larger area. 

Advantages of liquid pre-emergent herbicides:

  • Allow for a more precise and even application (cracks in a driveway or sidewalk, for example), covering more ground than granular herbicides
  • Require less water to work 
  • Work faster than granular pre-emergents
  • Smaller quantities are needed than if using granular herbicides, saving you time and money
  • Liquid pre-emergents can be mixed with fertilizer or other lawn care products needed for your lawn and applied with a sprayer
  • Require less effort to transport and a smaller storage area

Disadvantages of liquid pre-emergent herbicides:

  • You must follow specific measurements, which may be challenging for people who aren’t familiar with these chemicals
  • Harder to apply in smaller, more targeted areas
  • Liquid pre-emergents take more prep time than granular ones

Pro tip: Note that more concentrated liquid formulas can be extremely strong. Use these concentrated formulas with caution if you’re applying them to a smaller space. 

Bottom line: For a precise, affordable, and even application of your pre-emergent herbicide, liquid formulas are your best bet. 

Granular pre-emergent herbicides

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Granular pre-emergent herbicides involve less prep time but require a bit more effort (purchasing a spreader) and time (slower to act) than liquid pre-emergents, so they’re less commonly used. 

Advantages of granular pre-emergent herbicides:

  • Involve little mixing or measuring
  • Granules are easier to spread
  • Usually cheaper than their liquid counterparts
  • Label usually makes it easy to determine how many square feet these herbicides will cover

Disadvantages of granular pre-emergent herbicides:

  • Hard to distribute evenly
  • Require more water
  • Tend to work slower than liquid formulas

Pro tip: Granular pre-emergents with smaller particles are easier to spread evenly. 

Bottom line: Granular pre-emergents are usually recommended for smaller lawns, as the disadvantages are less of an issue in limited areas.

Synthetic pre-emergent herbicides

Synthetic pre-emergent herbicides, also known as non-organic herbicides, are chemically designed to kill weeds. They include active ingredients such as oxadiazon, dithiopyr, and prodiamine.

Synthetic pre-emergents are best if these weeds are a problem in your yard: broad leaves, bramble, and traditional and ornamental grasses.

Advantages of synthetic pre-emergent herbicides:

  • Chemical pre-emergents need to be reviewed and tested by the EPA
  • Easily available 
  • Fast acting
  • Affordable 

Disadvantages of synthetic pre-emergent herbicides:

  • Can harm the environment 
  • Can affect the fertility of your soil

Common chemicals found in synthetic pre-emergent herbicides:

The chemicals used in synthetic pre-emergent herbicides matter, and each one works better on different weeds. Common types found in pre-emergents include: 

  • Prodiamine – Prevents both grassy weeds and broadleaf weeds. These include chickweed, witchgrass, clover, thistle, crabgrass, creeping bentgrass, and dandelion. Prodiamine struggles to control nutsedge. It’s safe to use on established lawns.
  • Dithiopyr – Prevents chickweed, oxalis, clovers, dandelion, bittercress, crabgrass, goosegrass, and poa annua. Dithiopyr has a tough time controlling spurge and broadleaf weeds. 
  • Benefin (aka Benfluralin) – Prevents crabgrass, carpetweed, ryegrass, chickweed, annual bluegrass, sandbur, pigweed, foxtails, goosegrass, and knotweed. 
  • Trifluralin – Prevents summer grass, chickweed, redroot, annual bluegrass, and red-dead nettle. Trifluralin isn’t your best choice to prevent thistle, clover, daisies, and wild turnips. 
  • Isoxaben – Prevents dandelion, thistle, clover, and chickweed, but it’s not your best bet for controlling grassy weeds like crabgrass, annual ryegrass, and carpetgrass. 
  • Oxadiazon – Prevents crabgrass, clover, dandelion, thistle, and knotweed. There are better options to prevent chickweed, spurge, and pearlwort. 

A pre-emergent herbicide can contain one or multiple ingredients (most often prodiamine and dithiopyr), so consider your needs when selecting a type. 

Pro tip: These chemicals have a low toxicity level so that they won’t harm you, your children, or your pets, but you should still take safety precautions when handling chemical pre-emergents. If you’re environmentally conscious, organic pre-emergent may better suit your needs.

Organic pre-emergent herbicides

worker spraying herbicide or insecticide on a plant
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With an increase in eco-friendly products, many synthetic pre-emergents have been replaced with organic alternatives, such as vinegar or corn gluten. The latter has become the most common option due to its weed-fighting abilities and fertilizer qualities, doing wonders for soil health.

Organic pre-emergent weed killers are best if you struggle with clover, dandelion, and crabgrass in your lawn.

Advantages of organic pre-emergent herbicides:

  • Great for your soil. Corn gluten has a high amount of nitrogen, and as the nitrogen is released over a few months, it works to prevent any weeds from growing.
  • Non-harmful to the environment

Disadvantages of organic pre-emergent herbicides:

  • Can attract bugs 
  • Slow to release 
  • Expensive 

How to choose the best pre-emergent herbicide for your lawn

Pre-emergents are not one-size-fits-all for every lawn. From the difference in how you apply granular and liquid formulas to the wide range of ingredients found in each herbicide, finding the right type for your yard can take some digging. 

Choosing a pre-emergent herbicide should be based on: 

  • The size of your lawn
  • The type of weeds you have
  • The amount of prep time you have
  • Whether you require organic options 

Once you’ve answered these questions, you can whittle down the many options of pre-emergent herbicides to find the best one for your yard. To help you shop, we’ve compiled a list of the best pre-emergent herbicides.

FAQ about pre-emergent herbicides

How long do pre-emergent herbicides last?

The lifespan of pre-emergent herbicides usually ranges between 9 and 12 weeks, though this isn’t a definitive rule. Some last longer than others, depending on the type. Check the label for application instructions.

What time of year is best for applying pre-emergent herbicide?

Spring is the ideal season to catch weeds before they sprout (using pre-emergent herbicide). Fall is also a good time to apply pre-emergent because weeds that grow during this time, such as clover, thistle, ivy, and dandelion, are particularly vulnerable ahead of the cold season.

Will I damage my lawn if I use too much pre-emergent?

Applying too much pre-emergent can certainly happen, which usually leads to stunted grass growth. Likewise, skipping an application can result in weeds exploding all over your lawn. To prevent headaches, follow the label instructions and the abovementioned rules for choosing the right type of herbicide for your lawn.

Which pre-emergent lasts the longest?

Barricade offers the most prolonged and effective weed control, able to withstand rainfall, irrigation, and snow to protect your grass against pesky weeds such as crabgrass. It has a stain-free formula and stays put wherever your turfgrass may be (including hillsides or steep slopes).

Next steps

The best time to apply your pre-emergent herbicide depends on where you live, the season, and the ground temperature. You’ll need time and effort to research the best options for your yard.

If you’d rather not deal with the application yourself, a lawn care pro can handle it all for you. Quick, professional services are just a click or phone call away.

Main Photo Credit: Hello I’m Nik | Unsplash

Andie Ioó

In my free time, I enjoy traveling with my husband, sports, trying out new recipes, reading, and watching reruns of '90s TV shows. As a way to relax and decompress, I enjoy landscaping around my little yard and DIY home projects.