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The 5 Best Weed Killers (2021 Review)

An effective herbicide can get rid of a variety of weeds that have invaded your lawn. In this review, the This Old House Reviews Team researched the five best weed killers on Amazon to help you find the product that’s right for you. The products included in this article are available at various home improvement stores, local home centers, and online retailers like Amazon.

Weed Killer Courtesy Amazon

Whether they appear on your lawn, patio, garden, or fence, weeds are an annoyance for any homeowner. Thankfully, there are many easy-to-use and effective weed killers to help remove these unwanted plants. To help you select the weed killer that’s right for you, the This Old House Reviews Team researched the best weed killers on Amazon. Here are our top five recommendations.

Best For Gravel: RM43 43% Glyphosate Plus Weed Preventer

This weed killer contains 43% glyphosate. This ingredient kills any plants it comes into contact with, so it works best for weeds on pavement or gravel. With one gallon of concentrated liquid for over 17,000 square feet, this product will protect a large area.

Key Features

  • Comes in a one-gallon bottle of concentrate
  • Treats 17,297 square feet for up to a year
  • Rainproof within two hours
  • Kills weeds
  • Works on surfaces without vegetation

What Customers Are Saying

Out of over 4,000 reviews, this product has an overall rating of 4.6 stars out of 5 stars. Among reviewers, 90% gave this weed killer 4 or 5 stars, while 5% rated it 1 or 2 stars.

Those who left positive reviews said that this weed killer worked well on large areas and was simple to use. However, dissatisfied customers said that it took too long to kick in or that it was as effective as cheaper, generic brands.

Most Customizable: Spectracide Weed & Grass Killer

This concentrated weed killer produces visual results within three hours of application on driveways, fences, flower beds, shrubs, and other surfaces. With multiple size and quantity options, your purchase can be customized to meet the specific needs of your yard.

Key Features

  • Comes in a 64-ounce bottle of concentrate
  • Available in other bottle sizes and quantities
  • Rainproof after 15 minutes
  • Shows results in as little as three hours
  • Kills weeds and grasses
  • Works on driveways, walkways, fences, trees, flower beds, shrubs, and more

What Customers Are Saying

With over 1,850 reviews, this weed killer holds an average rating of 4.6 stars out of 5 stars. Among reviewers, 92% gave 4- or 5-star reviews, while 3% left 1- or 2-star reviews.

Happy customers said that this product was long-lasting, fast-working, and persistent with tough weeds. However, other reviewers claimed that it caused damage to lawns and that it didn’t work as advertised.

Best For Multiple Weed Types: Roundup All-in-One Weed Killer For Lawns

With the ability to kill over 250 types of weeds, including crabgrass, dandelions, and clovers, this weed killer eliminates almost every type of plant pest in your garden. This weed killer doesn’t damage lawns either, allowing you to spray it directly on grass or flower beds.

Key Features

  • Comes in a 1.33-gallon spray bottle
  • Available in ready-to-spray and concentrate bottles
  • Rainproof in as little as three hours
  • Kills Northern grasses

What Customers Are Saying

With nearly 2,000 reviews, this product holds an average rating of 4.3 stars out of 5 stars. A total of 81% of customers gave this product 4- or 5-star reviews, while 10% gave it 1- or 2-star reviews.

Those who liked this weed killer said that it was easy to spread and killed multiple types of plants with a minimal amount of spray. Dissatisfied customers didn’t like that it contained toxic ingredients.

Best For Flower Beds: Ortho GroundClear Weed & Grass Killer

With visible results in just 15 minutes, this weed killer can eliminate unwanted plants from your flower bed or garden in a snap. This spray starts working immediately on all types of weeds and grasses.

Key Features

  • Comes in a one-gallon spray bottle
  • Rainproof within two hours
  • Shows results in 15 minutes
  • Kills weeds and grasses
  • Works on hardscapes, landscape beds, and vegetable gardens

What Customers Are Saying

This weed killer has nearly 2,000 reviews on Amazon with an average rating of 4.3 stars out of 5 stars. Among those who left reviews, 81% gave this product a rating of 4 or 5 stars, while 10% gave it a rating of 1 or 2 stars.

Satisfied customers said that this weed killer worked quickly, didn’t kill wanted plants, and featured a simple-to-operate nozzle and wand. However, other customers said that it didn’t eliminate all of their weeds even after going through the entire bottle.

Best Vinegar Weed Killer: Green Gobbler Weed & Grass Killer

Without using harsh chemicals or glyphosate, this product is effective on surfaces ranging from sidewalks to flower beds. It provides visual results within 24 hours with its pet-friendly and non-toxic formula.

Key Features

  • Comes in a one-gallon spray bottle
  • Shows results within 24 hours
  • Kills crabgrass, dandelions, clovers, and more
  • Works on mulch beds, sidewalks, driveways, flower beds, and more

What Customers Are Saying

Out of over 8,000 reviews on Amazon, this weed killer has an average rating of 4.2 stars out of 5 stars. Of those reviews, 79% had 4 or 5 stars, while 13% had 1 or 2 stars.

Customers who left positive reviews liked that this product was inexpensive and safe for families with children and pets. Dissatisfied customers said that it left an unpleasant smell and caused damage to wood surfaces.

Buyer’s Guide

Not all weed killers work well for every surface or weed. Here are several factors to consider when determining which weed killer is best for your lawn.


Different types of weed killers are recommended for different types of plants and areas of application. Here are some common types of weed killers to look out for.


This type of weed killer kills plants as soon as it makes contact with them. Contact weed killers don’t attack the root system, but they weaken weeds after multiple uses. This type of weed killer is effective for annual weeds that consistently reappear.


Systemic weed killers are applied directly to the foliage of a plant. They take several weeks to start working, but they fight the plant’s internal root system. This type of weed killer is good for plants that are difficult to kill, such as dandelions and poison ivy.


These weed killers poison soil, killing all plants within the treated area. They can be long-lasting, so it’s best to avoid using this type of weed killer in areas that contain edible plants.


Emergence refers to how far along in the weed’s growth cycle that weed killer needs to be applied. Some weed killers are pre-emergent, meaning they should be applied to prevent weeds from growing. Post-emergent weed killers are used for weeds that have already sprouted. They kill the plant while also ensuring it doesn’t grow back.


If you’re using a weed killer on flower beds or gardens, it’s critical to look for selective weed killers, as they avoid beneficial plants and solely target weeds. Meanwhile, non-selective weed killers destroy all plants in the vicinity.

Frequently Asked Questions

How do weed killers work?

Generally, weed killers are herbicides that interfere with weed growth by either destroying their root formation or restricting the growth and development of their cells, causing them to eventually die.

Are weed killers dangerous around pets?

It depends on the weed killer. Some aren’t safe for households with pets, while others are safe once they’re dry. The safest option is a weed killer with an organic formula.

How long does it take for weed killers to work?

Typical weed killers will take anywhere from two to six weeks to fully kill the root of a plant. Certain types of herbicides will produce faster results, but these herbicides kill the flowering part of the plant and not its root system.

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