There are four main types of weed killer. Systemic, contact, residual and selective:

• Systemic weed killers will kill everything, including the roots of the plant.
• Contact weed killers only kill the parts of the weed they come into contact with.
• Residual weed killers or soil acting weed killers sit in soil to prevent anything growing.
• Selective weed killers are commonly used in lawns to kill lawn weeds & not grass.

Did you know that most of the effective ones work by messing with the plant's photosynthesis process? Yup, it's true! When you apply a weed killer, it gets absorbed by the plant and acts like a poison, slowly but surely killing it off.

Almost all powerful weed killers should be applied to the foliage (leaves) of the plants your trying to kill, a common misconception is to apply it to the "roots" - this is a waste!

Coat all the green parts in weed killer and be PATIENT!

Unlike hand weeding, weed killers take time to work, whatever manufacturers say - there are no weed killers that work right away. It takes time to see results, it may be a week, it may be 30 days: there are no instant weed killers - if you want fast results, use your hands or dig them out.

Now, before you go spraying this stuff all willy-nilly, a word of caution: you need to be careful when using garden chemicals like weed killers. If used incorrectly, they can be harmful to the environment and other critters that call your garden home. 

So, always read the label and follow the instructions for safe & effective use.

But don't worry, there are plenty of eco-friendly and pet-friendly options out there that won't harm the planet or your furry friends. So, whether you're dealing with stubborn woody weeds or pesky annuals, there's a weed killer out there that will do the trick without causing any harm.

And hey, if you're still not sold on the idea of using weed killers, that's totally okay! Hand weeding is always a great option and can be a fun way to get some exercise and fresh air. Plus, you get the satisfaction of seeing those pesky plants gone for good!

What is the strongest thing to kill weeds?

Different strokes for different folks.

Different weeds and locations require different kinds of weed killer.

Therefore there is no one strongest weed killer that works everywhere.

Instead there are numerous strong weed killers that are suitable for different jobs.

Glyphosate:

The worlds most popular weed killer. It is used across the world in gardens, farms & public places. We love this stuff. It's not difficult to see why, it's an effective and super strong weed killer.

Glyphosate is systemic, will kill grass and pretty much every other plant it touches. Used to kill annuals, perennials, woody perennials and tree stumps - it is effective against ALL weeds.

Glyphosate is used with 85% of GM crops grown globally.

Worldwide we consume roughly 650,000 tonnes of Glyphosate annually worth around $6.5 billion and it's use keeps on increasing in large part due to it's use with GM crops (source).

Why is Glyphosate used so much?

• Glyphosate kills weeds without harming crops. Many GM crops have been engineered to be resistant to Glyphosate meaning large areas can be treated efficiently.
• It's cheap and effective. It works on a broad range of weeds and is cheaper than most other strong weed killers.
• It's not toxic to humans. There is some debate about this, long term exposure may cause harm but it is widely approved for use. Please always read the label when using herbicides.
• It doesn't persist in the environment. You can treat an area and then a few weeks later plant in the same area with no residues affecting future growth.

Glyphosate is by far the most effective weed killer on the market in the UK. It is used to kill a wide variety of weeds on a wide variety of surfaces, it is the best all purpose weed killer we have.

Glyphosate is a systemic weed killer meaning it is absorbed through the leaves and stems and translocated throughout the whole plant, killing it from the inside out, right down to the roots.

It certainly sounds like a miracle weed killer huh?

Well there are a couple of downsides:

1.  The biggest complaint about Glyphosate is that "it didn't work" - in most cases the product was applied incorrectly: apply on a day with no rain and coat all the leaves.
2. Glyphosate is not a quick weed killer, expect to wait to see results, depending on the conditions and type of weed it can take anywhere from 7-30 days to work.
3. You cannot use Glyphosate in or near sources of water. It persists in aquatic environments and is harmful to aquatic invertebrates, do not use in or near water sources!

If you're looking for a strong, effective weed killer that kills everything then your best choice is Glyphosate, it is sold widely across the UK and most importantly - it works!

Triclopyr

Triclopyr - the tough weed wrangler of the herbicide world! It is a selective & systemic weed killer, meaning it can take down the tough weeds without harming the good guys (aka grass). So if you're looking to eliminate tough weeds in and around your lawn, Triclopyr is definitely a solid option.

Triclopyr is mainly used to tackle woody, viney, tough, deep rooted weeds such as Brambles, thistles, docks, nettles & saplings to varying degrees of effectiveness.

So if you're in the market for a powerful weed killer that won't harm your grass, Triclopyr should be top of your list - although there are better lawn weeds killers for specific lawn weeds.

• Triclopyr is an effective herbicide for controlling woody plants and broadleaf weeds
• It is relatively inexpensive and easy to use
• It is versatile and can be formulated in a variety of ways
• It can be used in combination with other herbicides for improved effectiveness
• It is less affected by environmental factors than some other herbicides.

It's formulated so that it won't kill grass and can be used safely in turfed areas. Typically mixed with water in a knapsack or sprayer but can also be used in a watering can.

Triclopyr like other industrial weed killers also has it's disadvantages:

1. It persists in soil so you cannot use it to clear a large area then replant afterwards.
2. It is ineffective against a range of grass based weeds so you may need another.
3. It takes time to work: Like other weed killers there are no instantaneous results.

Horticultural Vinegar

Alright, let's talk about horticultural vinegar - AKA acetic acid. It has been touted as a miracle weed killer and has become pretty popular among home gardeners who want to avoid the heavy-duty industrial strength weed killers.

But here's the thing - horticultural vinegar is not some magical homemade remedy. It's actually a commercial weed killer just like the rest of them. So while you might not want to pour it on your fish and chips, it can be effective in killing certain types of weeds.

Horticultural vinegar is an acid based, contact weed killer:

• Fast acting weed killer that burns away the weeds you spray it onto.
• Contains no Glyphosate and can be used in organic settings.
• Works on a wide variety of plant life and is less effected by environmental factors.

Horticultural vinegar often comes in large 5, 10 or 20 litre tubs which are commonly diluted in a 4:1 ratio (4 parts vinegar, 1 part water). There are also differing concentrations ranging from 20% acetic acid up to 40% with the latter being more expensive.

Horticultural vinegar may well be an effective industrial weed killer for those wishing to avoid Glyphosate but it does have numerous disadvantages:

1. It doesn't kill the roots, as a contact weed killer it only kills the top part of the weed, leaving the roots intact - your weeds will regrow, eventually.
2. It may well be just as dangerous as Glyphosate, several studies indicate it is more toxic than Glyphosate to humans.
3. It is much more expensive: As it doesn't kill the whole weed you will have to reapply more often and a 10 litre container may only make 15 litres of weed killer, compare this to other commercial weed killers which will often make hundreds of litres per 10 litre.

There you have it, horticultural vinegar is ranked 3rd in our list of strong industrial weed killers for a reason - it's not as effective as the other two & it's more expensive but if your looking for a more natural & organic weed killer then this may well be the choice for you.

Sodium Chlorate

Was a popular weed killer in the UK that was long lasting and worked very well.

Let me hit you with some sodium chlorate knowledge! Back in the day, this chemical was primarily used as a pesticide to take down pesky weeds and other unwanted plant life. But here's the catch - sodium chlorate is not exactly a friend to humans or the environment.

In fact, it's considered pretty harmful. So much so that the EU has banned the sale and use of sodium chlorate in plant protection products and pesticides. That's right, folks - it's a no-go. However, companies can still produce the stuff for transport and sale outside of the EU.

So if you're looking for a way to get rid of some weeds, you might want to skip the sodium chlorate and opt for a safer alternative. Your lungs (and the planet) will thank you!

YOU CANNOT BUY SODIUM CHLORATE IN THE UK

Source: https://assets.publishing.service.gov.uk

2,4-D (2,4-Dichlorophenoxyacetic acid)

2,4-D is commonly used to control Broadleaf weeds in lawns and turf.

It's a synthetic chemical if used incorrectly it can be toxic to humans and other animals if ingested or comes into contact with the skin.

2,4-D is a selective weed killer, it won't kill grass and is commonly applied to lawns for long lasting control of weeds in turf.

Why is 2,4-D used so much?

• It's relatively inexpensive. As a synthetic chemical it can be formulated quickly and in a variety of ways making it a popular choice for farmers and homeowners alike.
• It's selective. Unlike Glyphosate which kills all plant life, 2,4-d is selective. It is particularly useful for controlling broadleaf weeds in grass & crops like corn, wheat & soybeans.
• It can be combined. It can be used in combination with other herbicides, which allows farmers to control a wider range of weeds with a single application..
• It effective. Because it is a synthetic chemical, 2,4-D is less likely to be affected by environmental factors such as temperature and humidity, which makes it more reliable than some other herbicides.

2,4-d is most widely used by homeowners on lawns and turfed areas. It is more commonly used by farmers and professional users.

It works on most broadleaf weeds but will not kill grassy weeds.

If you're looking for a strong, effective weed killer for your lawn then #1 choice should be 2,4-d.

Dicamba

A powerful weed killer that doesn't kill grass, Dicamba has been used for decades to control many types of lawn weeds including crabgrass, dandelions, daisies, clover & more. Dicamba contains the active ingredient 3,6-dichloro-2-methoxybenzoic acid.

Fluroxypyr

Fluroxypyr is a type of weed-killing chemical that is used to control unwanted plants such as broadleaf weeds and woody brush. It works by tricking these plants into thinking they have too much of a hormone called auxin, which causes them to grow uncontrollably and eventually die.

Unlike some other weed killers, fluroxypyr is a systemic and selective weed killer, it doesn't harm grass or grassy weeds but will take down most broadleaf weeds.

• Can be used to control a wide variety of broadleaf and woody weeds in or around grass.
• Doesn't harm grass or croplands but effective against a wide range of weeds.
• Relatively inexpensive and can be mixed with other herbicides to increase effectiveness.

Vinegar:

The most talked about DIY weed killer is vinegar, it's great on chips and crisps but can it really kill those PESKY weeds in your garden?

Like most myths that spread like wildfire there is some truth in it, vinegar does kill weeds - only some kinds and like horticultural vinegar it only burns away the visible part of the weed, it doesn't kill the roots, so your weeds will likely regrow.

Vinegar is most effective on young, small or weakened weeds that are actively growing, you would need industrial quantities for large weeds like brambles and even then it probably still wouldn't work - as it doesn't kill the roots!

Vinegar should be applied on a warm day with no chance of rain, don't dilute it! Just spray it right from the bottle onto your weeds (like in the picture above).

Special mention goes to horticultural vinegar which has a higher concentration of acid, this is more effective than regular vinegar but it's not as strong as a powerful commercial weed killer.

Salt:

The oldest weed killer. People have been using salt to kill weeds for centuries. It's also useful for combating other garden pests. Enemy combatants would salt each others land to prevent crops from growing leading to starvation. 

Pretty evil huh?

Salt is a non selective and is fairly effective against a wide range of weeds.

• Best used against weeds growing in paving cracks or gravel as it can harm your soil, preventing regrowth - do not use salt in lawns: you will ruin your lawn.
• Not very cost effective: 1 bottle of table salt will treat roughly 1m2, this is quite expensive when compared with an industrial or commercial weed killer.
• If it rains alot, the salt will be washed away before it has had a chance to become effective.
• Time consuming to apply. Shake the salt directly onto the weeds, this can take a while if you have a lot of weeds and may be impossible to do if it is windy.

Salt is about as natural as they come, it is widely available, safe and fairly effective against a broad range of weeds, it isn't a substitute for a strong weed killer but if your worried about safety or want to do things a more natural way then there is no harm in trying salt first.