The Best Weed Killers of 2021

Control dandelion, crabgrass, and other unwelcome garden guests with the right weed killer for your needs. Ahead, learn about the different types of weed killers and how to choose between them—and don't miss our roundup of top-favorite picks!

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The Best Weed Killer Options

Photo: depositphotos.com

Whether they crop up on your lawn, in a flower bed, or along the perimeter of a fence, weeds are the gardener’s age-old enemy. They make your yard unsightly, your walkway unkempt, and they compete with neighboring plants for sunlight, water, and nutrients, causing your cherished plants to weaken and be susceptible to pests and disease. Weed species can even spread and disrupt natural habitats. Worst of all, weeds just seem to keep coming back no matter what you do.

Fortunately, there are a few options for weeding these invaders out for good: deadheading weeds with garden shears or a weed wacker (cutting off the tops), removing them from the soil by hand, or using weed killers. Of these methods, deadheading is generally useful only for annual plants that don’t have extensive root systems and that die when the tops are separated from the roots. Pulling weeds by hand, meanwhile, is impractical if you have large number of weeds due to the effort involved (not least because doing so effectively requires digging up the roots to keep them from growing back). The limits of these manual methods make commercial weed killers the more fail-safe, flexible option for eradicating weeds—provided you choose the right one for the job.

Read on to learn what to look for in a weed killer and why the below are our top-favorite picks among the best weed killer options available:

  1. BEST PRE EMERGENT: The Andersons Barricade Granular Weed Control
  2. BEST POST EMERGENT: Green Gobbler Vinegar Weed & Grass Killer
  3. BEST SELECTIVE: Southern Ag Amine 2,4-D Weed Killer
  4. BEST CONTACT: Spectracide Weed & Grass Killer Concentrate
  5. BEST SYSTEMIC: Ortho Nutsedge Killer for Lawns
The Best Weed Killer Options

Photo: depositphotos.com

Key Considerations for Choosing a Weed Killer

The type of weed killer you choose will dictate where you apply it, at which growth stage to apply it, which types of weeds it will kill, how it will impact plants nearby, and how long it will control weeds. This means that even a well-reviewed weed killer that’s not designed to solve your specific weed problem can result in product failures, and, hence, lingering weeds. To maximize product performance and minimize the risk of herbicide failure, factor in the following properties when choosing the right commercial weed killer for the job.

Emergence

Emergence refers to the stage of weed growth at which you must apply the weed killer.

  • Pre-emergent weed killers, sometimes labeled as “weed preventers,” target and kill the germinating (sprouting) seedlings of weeds before they emerge from the soil as weeds you can see. You generally apply them to the soil of lawns or gardens before you see signs of weeds; they will form a chemical barrier in the top layer of soil that will stop the growth of seedlings underground, in effect killing them.
  • Post-emergent weed killers, also known as herbicides, are used to control existing weeds that have already emerged from the soil. Apply them to the leaves and/or stems of visible weeds in garden beds or driveway or sidewalk cracks; the chemicals will kill the weeds either by destroying the foliage or stems or traveling down to the roots and killing the whole root system.

Selectivity

Selectivity is the ability of a weed killer to destroy weeds but leave surrounding plants unharmed.

  • Selective weed killers destroy weeds but not turfgrass or other beneficial plants in the vicinity, making them a good option for eradicating, for example, dandelions or thistles on the lawn or in a flower bed.
  • Non-selective weed killers eradicate weeds along with any other plants in the application area. Use them along the fence or pool or in driveway or sidewalk cracks, where you won’t put beneficial plants at risk.

Translocation

Translocation describes the movement of the product within a weed once it is taken up through the leaves, stems, or roots of the plant.

  • Contact weed killers don’t move within a weed after they enter it; rather, they kill the weed by destroying the plant part to which you apply them, usually within hours to days of application. They’re commonly used on annual weeds, such as crabgrass, nettle, and chickweed, which are easier to kill than perennial plants and generally die when the foliage or stems are destroyed.
  • Systemic weed killers move within a weed after they are absorbed, usually down to the roots, destroying the whole plant from the bottom up. You can expect to wait several days to several weeks to see results, although unlike contact weed killers, systemic products generally won’t state the specific period of time it takes to kill weeds. They’re a good option for perennial weeds, such as dandelion, poison ivy, or ragweed, which are typically more difficult to kill because of their deeper roots.

Persistence

Persistence is a measure of how long after application a weed killer remains in the soil and provides weed control before you have to reapply it.

  • More temporary weed killers degrade in soil within a few days to weeks, which forces you to reapply the product often to keep weeds at bay but allows you to quickly replant other plants in the area without interrupting their growth. This makes them a better option for gardens where you intend to plant flowers or vegetables in the near future or places where weeds seldom grow, like gaps between paver stones in the yard.
  • Longer-lasting weed killers stay in the soil and keep new weeds from growing in the application area for months or even a year after application. They’re a good option for lawns or gardens where you need lasting weed control, but they can also inhibit the germination of new plants you grow in the area for a longer period of time, so don’t use in areas where you plan to add new crops in the near future.

Our Top Picks

Best Pre Emergent

The Best Weed Killer Option: The Andersons Barricade Granular Weed Preventer
Photo: amazon.com

Nip baby weeds in the bud with this selective pre-emergent weed killer best suited for turfgrass and garden beds. It helps prevent over 30 types of weeds from growing—without harming most trees, shrubs, vines, or flowers nearby. Apply this granular weed killer to the soil or mulch and then water (or wait for the rain) to establish a protective soil barrier to block weed growth for four months to one year. One 18-pound bag covers between 2,500 to 10,000 square feet.

Pros

  • More particles per square inch for better control
  • Prevents more than 30 types of grass and weeds
  • Does not harm most trees, shrubs, and flowers
  • One bag can cover 2,500 to 10,000 square feet

Cons

  • Does not eliminate existing weeds
  • Need to mow first for better results


Best Post Emergent

The Best Weed Killer Option: Green Gobbler Vinegar Weed & Grass Killer
Photo: amazon.com

Sold in a one-gallon bottle that covers 1,200 square feet, this non-selective post-emergent herbicide works to control crabgrass, dandelion, and other pesky weeds, using a potent, pet-safe vinegar formula. Because it’s a non-specific weed killer, it’s best used near fence lines, pools, and patios, or in driveway or sidewalk cracks. To apply, fill a pump sprayer with the liquid herbicide or attach the supplied trigger sprayer, then point and spray; the fast-acting product can kill weeds within 24 hours and degrades in soil within days.

Pros

  • Non-selective
  • Pet-safe formula
  • Starts killing weeds within 24 hours
  • Degrades within days

Cons

  • Does not prevent weeds
  • Can kill any plants in the application area


Best Selective

The Best Weed Killer Option: Southern Ag Amine 24-D Weed Killer
Photo: amazon.com

This selective post-emergent herbicide targets weeds like dandelion and chickweed but does not affect plants that aren’t weeds. Dilute two to three tablespoons of the liquid concentrate in three to five gallons of water and spread with a hand-pump sprayer or a hose-end sprayer. It’s suited for use on lawns, pastures, rangelands, and along fences. The product provides weed control for six months to one year depending on the application site, and the one-quart bottle covers 21,000 to 32,000 square feet.

Pros

  • Kills broadleaf weeds like dandelion
  • Does not kill other plants
  • Provides weed control for 6 months or longer

Cons

  • Will not kill other types of weeds
  • Must mix with water before use


Best Contact

The Best Weed Killer Option: Spectracide Weed & Grass Killer Concentrate
Photo: amazon.com

This non-selective contact weed killer harnesses the fast-acting herbicide diquat dibromide to eliminate weeds and other vegetation on contact. Dilute 10 tablespoons of the liquid concentrate in a gallon of water, apply with a tank sprayer to the foliage of weeds like dandelion, clover, and ivy. The product typically works within 24 hours, and you can reapply it after seven days. The 16-ounce concentrate covers up to 1,500 square feet.

Pros

  • Will kill only what it contacts
  • May start killing weeds within 3 hours
  • Can be reapplied after 7 days
  • Rain or watering will not reduce effectiveness

Cons

  • Must mix with water
  • Not for weed prevention


Best Systemic

The Best Weed Killer Option: Ortho Nutsedge Killer for Lawns
Photo: amazon.com

To deal with the most stubborn lawn weeds, consider this sulfentrazone-based selective post-emergent herbicide. It can eliminate 50 hard-to-kill weeds like purple nutsedge and kyllinga without damaging the grass or tolerant surrounding plants. Application of this liquid formula is made easy by the built-in hose-end sprayer: Just connect the sprayer to your hose, turn on the water, and spray the systemic herbicide directly on weeds. You can reapply the herbicide after one month, and the 32-ounce bottle covers up to 5,000 square feet.

Pros

  • Kills 50 types of weeds
  • Can be applied again after 30 days
  • Rainproof after 2 hours
  • No mixing required

Cons

  • Need to use hose to apply it
  • Not for use over flowers, most ornamentals, vegetables


Our Verdict

While much depends on the weed-killing goals of each user, The Andersons Barricade Granular Weed Preventer is one of the best pre-emergent weed killers for most yards. If weeds have already appeared, try the Green Gobbler Vinegar Weed & Grass Killer as it is one of the best post-emergent weed killers.

How We Chose the Best Weed Killers

These recommendations for the best weed killer include a variety of products to meet the weed- killing needs of typical users who want to maintain a residential landscape. We narrowed our research to focus primarily on liquid weed killers, as those are some of the most popular on the market due to their ease of use. However, we found that one granular weed killer ranked highest in the pre-emergent category.

We also evaluated the weed killers based on how long each product stays in the ground and whether it is pre-emergent or post-emergent, selective or nonselective, and contact or systemic. While there are weed killers ranked on our list that are broad killers that can work quickly and have long-lasting effects, there are others that are designed for killing either a targeted weed type or targeted placement with little effect on the surrounding landscaping.

FAQs

Q. What’s the best weed killer for driveways?

While it depends on the type of weeds growing in the driveway, the best weed killer is one that eliminates any plants that have grown and prevents new growth from creating or expanding any unwanted cracks. For this, both a pre-emergent and post-emergent would be helpful.

Q. Are weed killers toxic to people and animals?

Yes, some weed killers can be toxic to people and animals. A recent study from the University of Maryland suggests that even toxic weed killers can be safe around people and pets if the directions are followed closely.

Q. What kills weed permanently?

The best bet for permanently killing weeds is pulling them out of the ground from the root.

Q. Can I use vinegar as a weed killer?

Yes, vinegar can be used as a weed killer. Some commercial weed killers use concentrated vinegar as a natural alternative to synthetic chemicals.