The best weed killer

Bob Beacham

Unfortunately, weed killers can’t tell good plants from bad! Don’t spray on a windy day. Consider hand weeding or use a weed torch around vegetables and flowers.

Weeds spoil the appearance of your driveway, paths, lawn, and garden. If you don't stay on top of eliminating them, they can soon get out of hand. The easiest way to do that is with a good weed killer. They can also be effective if you're clearing overgrown areas prior to creating new beds and borders. They aren't all the same though, so we've been investigating what you need to look for. Our top pick, Ortho GroundClear Concentrate, is a great all-rounder, quickly clearing weeds and protecting against future growth. It's not necessarily right for all situations though, as this short article explains.

Considerations when choosing weed killers

There are two basic types of weed killer: nonselective and selective. Some work by blocking photosynthesis, thus starving the weed. Some produce toxins within the weed. Others destroy cell structure. There are those that work by destroying the areas they contact, but most are systemic -- they're absorbed by the plant, killing the growth above ground and also the roots.

Which method a weed killer uses isn't really important, but separating the two main types is. Nonselective weed killers kill all plant matter. They're very effective against weeds, but they also attack flowers, vegetables, and grass, so you have to be careful where you spray it. They're highly recommended for hard surfaces and fence lines but not for lawns and borders.

Selective weed killers attack broadleaf plants, which includes most types of weeds. They're fine with the majority of grasses, so you can use them to get rid of dandelions in the lawn, for example. However, lots of flowers and vegetables fall into the broadleaf category, so again, careful application is needed.

Some weed killers have an additional component that prevents regrowth. There are also preventative products that can be used to stop weeds before they appear, though these products don't kill existing weeds. Some are safe for use with vegetables but might not be safe for lawns.

As you can see, weed killers are becoming more sophisticated and more specific. That's great news because it means there's almost certainly a precise solution for your weed problem. However, it's vital to check the instructions carefully before you apply so you know what the product will kill and which areas you can treat safely.

Weed killer application

Weed killers come in three forms:

Concentrated liquid, which you dilute in your own sprayer
Ready-to-use liquids, which sometimes have a spray wand included
Granular, which is spread on the ground

Liquids work faster, and are easier to apply over a large area. However, wind can carry them from your path onto your lawn, so you need to be careful. Granules are slower, but you can apply them precisely, which is important if you're trying to control weeds but not damage neighboring plants.


Concentrates often work out cheaper than ready-to use, but prices vary enormously. You need to take into account coverage, as well as price per gallon (or per pound if it's granules). Fortunately, even the best aren't particularly expensive, so you can focus on what's right for your application.


Be patient; makers have been known to exaggerate how fast weed killers work!
Concentrates should be diluted as instructed. Making it stronger will not make it better.
A second application may be required.
Never use your weed killer sprayer for watering or fertilizing. Buy two sprayers. Mark the bottle or tank in some way so you don't mix them up.
Granular weed killers usually have an unpleasant smell to deter pets, but it's a good idea to keep them out of the treated area if possible.


Q. When should I apply weed killer?

A. Any day when you're fairly sure of having four or five hours without rain will be fine. If it rains after that, enough will have been absorbed to do the job. Avoid hot, sunny days if you're using a liquid, because it can evaporate before it's had time to work properly.

Q. Why are some weed killers banned in California?

A. The California legislature has ruled that glyphosate is carcinogenic. However, other states have not followed suit. The U.S. Environmental Protection Agency classifies the chemical as Group E, low toxicity, and does not believe it causes cancer in humans.

Weed killers we recommend

Best of the best: Ortho GroundClear Concentrate

Our take: Powerful and effective weed killer for patios, pathways, and drives.

What we like: Results start to show within hours. Can prevent regrowth for long periods. A little goes a long way. Low glyphosate content.

What we dislike: Expensive. Can't be used in lawns. Not legal in California.

Best bang for your buck: Southern Ag Amine Weed Killer

Our take: Economical control of broadleaf weeds in a wide variety of situations.

What we like: Selective weed killer works on clover, dock, etc., but won't harm lawns, pasture or other grassed areas. Low cost, good coverage (follow instructions carefully).

What we dislike: Odor isn't pleasant. May require more than one application.

Choice 3: BioAdvanced Triclopyr Brush Killer

Our take: The one to use for the tough, pervasive weeds that others won't touch.

What we like: Effective against bramble, kudzu, poison oak and lots of other woody plants and thick brush. Ready to use. Comes with its own spray wand.

What we dislike: Nonselective. Highly toxic. Keep away from children and animals.

Bob Beacham is a writer for BestReviews. BestReviews is a product review company with a singular mission: to help simplify your purchasing decisions and save you time and money. BestReviews never accepts free products from manufacturers and purchases every product it reviews with its own funds.

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