Types of Weed Killers – How to Choose the Right One


Have you been struggling to kill weeds?

You’re not alone. Unwanted vegetation is a major problem for many, and a blight on otherwise beautiful lawns and gardens.

They look unsightly, they can smother desirable plants, and they can even cause structural damage.

And sometimes, they just won’t DIE!

But fear not – for help is at hand. In this article, we take a look at the different types of weed killers, and help you choose the right one for your botanical bother.

Let’s get stuck in, so we can get the weeds out.

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List of Weed Killers – The Abridged Version

If you’re in a rush, here’s an at-a-glance guide to all the types of weed killers we cover in this article.

Note that these terms can be used together, and we’ve included the most typical words and phrases you might find when shopping for such products.

weed killer being used on grass

You can have a broad-spectrum, post-emergent, contact, lawn herbicide – for example. We’ll just bust the jargon for you later in the article.

General weed killer types:

  • Liquids and granules.
  • Concentrated.
  • Pre-emergent.
  • Post-emergent.
  • Pre-plant.
  • Systemic.
  • Contact.
  • Residual.
  • Broad spectrum.
  • Selective/Non-selective.

Location specific weed killers:

  • Lawn.
  • Flower and vegetable bed.
  • Driveway and patio.
  • Stump killers.
  • Organic/pet safe/non-toxic.

Stay with us as we explore each in more detail, including how and where to use them for the best results, as well as a section on weed killer alternatives – if you’re not comfortable using chemicals.

General Weed Killer Types

The following terms are some of the words and phrases you might find in the specifications of herbicides, and understanding each is key to choosing the right products for killing weeds.

Liquids and Granules

First up, you’ll notice that herbicides come in two forms – liquid or granular.

Liquids can be sprayed on neat, using the bottle the herbicide came in, or it can be decanted into backpack, tank, or pull-behind sprayers.

These types of weed killers are usually concentrated (more on that, below).

Granular is a “dry” herbicide, but often needs water to be activated, after it has been sprinkled in the desired location.

But which type is right for your needs?

The debate can rage long and hard, but I think it’s as simple as this:

For lawns and flower beds, use a weed and feed granular product that contains a mix of pre-emergent herbicide and plant food – before undesirables have had a chance to grow.

man spraying weed killer on grass

For just about anything else, a liquid weed killer is going to be more effective. When you’re talking about the best commercial herbicides on the market, they’re nearly always going to be liquids.

Concentrated

Concentrated weed killers are so-called because they’re designed to be mixed with water prior to dispensing. The best ratio for this will be explained on the product’s instructions.

This offers several advantages, including a larger yield than non-concentrated herbicides. You’ll often find a bottle of concentrate will last you several seasons.

You can also vary the strength of concentrated herbicides, which can be useful for tackling hard-to-kill plant life. Simply adjust the ratio of water to product to make it more potent.

Pre-emergent

Designed for use before you start seeing undesirable plant life, pre-emergent herbicides are a preventative measure you lay down to stop weeds from coming up.

Available in liquid and granular form, they often come as part of a mix of plant or lawn food/fertilizer, and are activated when they come into contact with water.

This forms a barrier in the soil, which stops weeds from germinating and breaking through.

Prevention is better than cure, as they say, and used properly, pre-emergent herbicides are one of the best ways to nip the problem in the bud – before the bud has a chance to form.

Go here for 12 of the best pre-emergent weed killers currently on the market.

Post-emergent

As you might expect, if you see post-emergent on the side of the weed killer bottle, it means it’s for treating weeds that have already taken root, and are showing above the surface.

Even with the best preparation and will in the world, weeds can still crop up in unexpected places, as nature will always find a way.

Purslane weed
Credit: https://www.flickr.com/photos/irisphotos/

The growing season of late spring into the summer causes an untreated yard to become a jungle. And for larger areas, or particularly stubborn problems, a post-emergent herbicide might be your best bet of taming it.

This article on the best post-emergent herbicides has all the extra info you need.

Pre-plant

Pre-plant herbicides can also be classed as pre-emergent weed killers, given the fact that they stop weeds from growing through the treated zone.

However, they are designed to be used where you want to sow seeds, and are commonly used in agriculture before planting crops like tomatoes and strawberries.

Systemic

Systemic weed control herbicides are inhibitors that work by attacking the system of the plant, preventing the production of chlorophyll, reducing proteins and nutrients, and effectively killing it from the inside-out.

Most commonly of the post-emergent variety, the chemical is absorbed through the leaves, and then transported to all other parts of the organism.

If you want to destroy the leaves, stems, nodes, buds, suckers, roots, and rhizomes, then look no further.

However, as you might expect, they might not be the fastest-acting weed killers out there, and total destruction can take weeks – depending on the product.

Systemic weed killers are best used when you have time and patience.

Contact

A contact herbicide is another post-emergent weed killer, which is designed to kill the leaves it comes into contact with.

Contact herbicides are often short-term solutions, as they might not kill right down to the root. They’re more suitable when you’re looking for a quick fix to an ugly problem.

However, one of their main advantages is they are fast-acting, and you should see results almost immediately.

Both contact and systemic herbicides typically work best when used in conjunction with a surfactant – which breaks the surface tension of the liquid, so the chemical stays on the leaves and has a better chance of absorption.

Residual

If the weed killer in your hands has the word “residual” somewhere on its person, then it means a herbicide that is designed to poison the soil.

Also known as “soil acting weed killers,” or “ground-clearing weed killers” they’re suitable for when you need to totally decimate an area of plant life, and prohibit any kind of germination anywhere they are dispensed.

But because they can inhibit any kind of growth for several months, you should only use residual weed killers where you don’t intend to plant anything else – at least, not any time soon.

As such, you’ll find that drive and patio herbicides are among those that can be described as residual – and you can find out more in the location-specific section coming up.

dollarweed growing on lawn

Broad Spectrum

Weed killers that are designed to tackle a variety of different plants – and are not limited to one particular species, are called “broad-spectrum” herbicides.

It simply means they are effective for use on multiple organisms. The popular herbicide glyphosate (most commonly found in Roundup products) is a broad-spectrum chemical compound.

And speaking of glyphosate, it’s probably one of the best chances you have of killing Bermuda grass – if it’s invading your lawn. Follow that link to find out more.

Selective/Non-Selective

When choosing any type of weed killer, you should be conscious of what it’s actually going to attack.

Selective herbicides are designed to kill certain plant species, while leaving others to their own devices.

A broadleaf weed killer for lawns is a common selective herbicide that many homeowners use. It attacks the dandelions, and not the grass, although it comes into contact with both.

On the other hand, non-selective herbicides will destroy anything green. Take extreme care when using any non-selective weed killer, as it’s going to damage any plant life it comes into contact with – even by accident.

If you need to deal with crabgrass in your lawn, for example, you should choose a selective herbicide that specifically targets that plant, while leaving the grass alone.

Follow that link for more natural crabgrass-removing solutions.

Location Specific Herbicides

The following examples might not strictly be “types” of weed killer, but it’s important to understand them, so you know exactly what you’re putting where.

Lawn

Lawn herbicides are specifically designed for use in the lawn. They won’t harm the turfgrasses, but they will attack unwanted invaders, like the six most common lawn weeds.

Tenacity is one such product that is safe to use on lawns, and I highly recommend it for controlling creeping Charlie – among other stubborn growths.

Lawn herbicides fall under the selective type, given the fact they only target certain plants. But can you spray weed killers on wet grass? That link will tell you everything you need to know.

However, even though the bottle might tell you it’s a selective pre-emergent herbicide safe for use on lawns, some gardeners are still, understandably, not happy about using them.

If that sounds like you, this article on the top ten ways to get rid of lawn weeds without chemicals will be right up your street.

Flower and Vegetable Bed

Likewise, herbicides that are designed for use around your flowers and vegetables can also be considered selective weed killers.

This article on the best herbicides for flower beds will tell you more – but I would be extremely careful when applying any kind of chemical near edibles.

It’s best to look for alternative methods, or try an organic weed killer that’s safe for vegetable patch use (more on this, below).

This article on how to get rid of grass in the vegetable garden might also help.

Driveway and Patio

Weeds poking up through cracks in the concrete, taking advantage of any gaps, and sprouting in and around brickwork can be extremely unsightly – and may be contributing to structural and surface damage.

Weeds in driveway

As we usually don’t need or want to plant anything else in such locations, we can afford to use stronger chemicals in treating these areas.

However, care must still be taken not to encourage run-off, and while all herbicides need to be applied at the right time, arguably, when laying down chemicals on concrete, it’s even more important.

Look for weed killers that are specifically designed for driveway and patio use – and you can follow that link for some great suggestions.

Stump Killers

As the moniker suggests, stump killers are used to destroy tree stumps, and/or particularly stubborn woody plants, vines, and bushes – which can be a challenge to kill and remove.

These products typically contain a variety of different chemicals and compounds and can come in liquid or granular form.

Both are dispensed in the same way, however – by drilling into the remains of the stump and applying the herbicide deep into the holes.

This article on the best stump killers on the market has more in-depth information.

Organic/Pet Safe/Non-Toxic

For delicate areas (such as vegetable patches), and/or if you have kids and furry friends running around, you might want to consider organic, or non-toxic weed killers.

Using harsher herbicides – such some glyphosate-infused brands – can be a concern when dispensed in and around desirable plants. Does grass grow back after Roundup? Follow that link to find out.

With that in mind, homeowners and gardeners often turn to less potent options, like these pet safe weed killers, for example.

And this article explores safer alternatives to Roundup, if you’re at all apprehensive about using this popular, but controversial brand.

But you might not want to use any kind of liquid herbicide at all, in which case, we’ve got you covered.

Weed Killer Alternatives

Of course, you don’t have to choose a chemical option for tackling weeds, and it should really be a last resort if you’ve tried everything else.

Herbicides, after all, are not that great for the environment in general. Water run off can easily occur, and you might end up with a toxic substance spreading somewhere it shouldn’t.

Thankfully, there are a number of alternative options out there. They include:

Manually removing the weeds by hand – which can be backbreaking work, but should be considered if you only have a few plants to treat. Try this article on how to get rid of dandelions naturally, for some inspiration.

Crowding out lawn weeds with new seedoverseeding a lawn to combat weeds allows the grass to take back control. Follow that link for tips on how to do it.

Weed barriers – more a pre-emergent solution, weed barrier fabrics should always be installed when building new flower beds and vegetable patches. Here’s a rundown of the best barriers out there.

Leave them alone – perhaps a controversial option, particularly for garden/lawn-proud homeowners, but have you considered not treating the weeds? There are several advantages.

Save money, time, and effort, no need to risk harsh chemicals in your yard, and the bees love the dandelions!

How to Choose the Right Weed Killer

There are times when we just don’t have the luxury of leaving weeds alone, and a herbicide is going to be the only effective solution.

But even armed with all the knowledge above, it can still be tricky to choose the right one.

Follow these four pro-tips for some additional help:

First Consideration – The Intended Outcome

Are you looking to merely control the weeds to allow desirable plants to dominate? Or do you want to destroy every living green thing over a given area? Are you spot treating a problem weed in your lawn?

Hands with gloves holding weeds

Consider how the weed killer is to be dispensed.

Is it soil or foliar applied? Liquid or granular? Neat or concentrated? How the product gets to the weeds or into the soil is an important factor in the process, as are the tools you need to apply it.

Persistence is key – or not?

How long do you need the weed killer to remain active? Choose a herbicide with higher residual activity if you want the area to remain clear of weeds and plant life for as long as possible.

The type of weed.

One of the most critical considerations when selecting the right herbicide is understanding what species it is required to attack. The video below should help you brush up on your weed identification skills.

Remember, whatever herbicide you decide to use, always take care when applying any chemical or compound in your garden.

Wait for optimum conditions with no wind or rain forecast until the product has had a chance to dry. Check the bottle to find out how long it takes for liquid weed killers to become rainfast.

Misuse of chemicals – particularly in residential areas – comes with heavy penalties. Use common sense, wear personal protective equipment, and consider your neighbors and others around you.

I wish you the best of luck.

Summary

That completes our rundown of the different types of weed killers, and hopefully, you should be armed with enough information to help you choose the right one for your needs.

Let us know if we’ve missed anything, which option you’ve gone for, or if you have any general weed-killing advice you’d like to share with the community.

Stay safe out there – and happy weeding!

Andy Gibson

My name's Gibson. Andy Gibson. I like to think of myself as the Bond of the backyard, that is if yard work ever became sexy. I write about everything about indoor and outdoor gardening and the dread-it-but-still-need-to-do-it chores around the yard, like cleaning out the gutter guards.

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