Last updated on July 13th, 2021
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Do you have weeds growing in your garden despite having treated them with every domestic weedkiller on the market? Maybe it’s time to move on to a professional-grade weed killer or at least the strongest weedkiller available which you can use without a chemicals licence.
These are strong highly concentrated liquids that need care in handling when you apply them with a garden sprayer. These industrial weed killers are usually systemic in that they get into the plant’s entire system and kill the whole plant, including the root.
Now although I have a recognised specified certificate for spraying Herbicides professionally. I often get asked which is the best weedkiller to use but I obviously cannot recommend professional products as they have strict limitations on who can use them.
However, all is not lost as there is still a handful of weedkillers that are extremely effective which anyone can use but my go-to weedkiller is Gallup Home & Garden Glyphosate Weedkiller. You can see the results below on a large area of very established tall weeds.
My Five Strongest Weed Killers review looks at those weed killers that the professionals use to kill the strongest perennial weeds and even tree stumps. One of the weed killers I review even kills everything but grass making it ideal for lawns. I list the pros and cons of each product and describe how each one works. Please be sure to also read my Buyer’s Guide which contains essential information about the different types of industrial weed killers and how to safely and effectively use them.
My Best Pick of the strongest weed killers is the Gallup Home & Garden Glyphosate Weed Killer. This is a best-selling glyphosate weed killer that is available to the general public and it’s very effective and is my go-to weedkiller, it really is that good. It can also be used around ponds as well as in your flower beds but care still must be taken.
Top 5 Strongest Weedkillers Review
1. Gallup Home & Garden Glyphosate Weedkiller
Gallop Glyphosate Weed Killer is probably the closest you will get to a professional-strength weedkiller available for industrial use and by far the best weedkiller that can be used by the general public. While many weedkillers have been banned over the years, Gallop has somehow avoided this fate, at least for now, and anyone can buy it.
Now I will start by saying this is the only weedkiller I use, its that effective at killing weeds that I simply don’t need to use any other type of weedkiller (except for a weedkiller I use on lawns of course) Whatever you do, don’t use this on your lawn unless you want to kill your lawn.
What I also like about this weedkiller is that it is a systemic weedkiller which is a foliar-applied translocated herbicide that can be used in aquatic areas unlike some other weedkillers available. You should, however, avoid contact with waterways such as rivers and ponds. Be super careful and use a little common sense here as it’s deadly stuff and in the wrong quantities can damage the environment.
To demonstrate how effective this weed killer is I recently sprayed a large area that had some very tall established weeds. Now in general, you want to spray weeds as they emerge so it’s fresh new foliage. This is when it’s most effective but I wanted to show that this weedkiller can even kill large established weeds which is where most other weedkillers don’t seem to be that effective.
The picture below is before I treated the area with Gallup Home & Garden weedkiller. This area of the nursery has not been used in a while and as you can see, the weeds have soon taken over.
After around a week and a half, the weeds had started to die as shown below, I only sprayed up to the centre so I could compare each side to get a good comparison.
Now 4-5 weeks later, these are the results as shown below. As you can see those weeds are dead and will not grow back as it has also killed the roots which is what you need. The only downside is that you need to remove those weeds by hand or if possible, simply rotavate into the soil using a mini tiller.
This is why it’s best to spray weeds when young and they usually die back to nothing.
Here it is again from another angle, I think you will agree it’s been very effective.
Gallop does kill most annual and deep-rooted perennial weeds and grasses. It will also usually kill mare’s tail which I recently tested at a friends house who has had some issues with it but it did take a couple of applications but it takes time. I would recommend spraying mare’s tail with the tops cut off. You usually need to spray a few times for the weed killer to be effective and even that is not guaranteed but I have had some good results with it.
Gallop is available in several different quantities including a 2-litre container, a 5-litre container and a 10-litre container. It has flexible application rates but I recommended that you start with the manufacturer’s standard mix of 300ml of concentrate for every 10 litres of water (24ml to every 1 litre of water). This is only a guide and measurements can change, so always read the instructions on the bottle before mixing. I actually buy the 2-litre container as it goes a long way, this will be more than enough for most people.
- Glyphosate Weed Killer that can be used in aquatic environments such as around ponds as well as in the usual flower beds.
- Kills most annual and perennial hard-to-kill weeds including mare’s tail which is notoriously hard to get rid of.
- Works with personal or garden sprayers.
- Available in different quantities and usual application ratio is 30ml of concentrate to 1L of water.
- Anyone, including children and pets, can go into the sprayed area AFTER the solution has dried.
- Biodegradable by the microorganisms in the soil so somewhat environmentally friendly.
- Kills lawns and any other plants it touches.
- Harmful if gets into water ways such as rivers and streams.
Gallop Glyphosate Weed Killer is one of the most popular industrial-strength weed killers for good reasons. It’s available for domestic gardeners and it works on most of the worst noxious weeds found in home garden landscapes. It’s easy to use as long as you follow the instructions and abide by the safety recommendations (and use your common sense).
I made Gallop Glyphosate Weed Killer the Best Pick in our review of the Strongest Weed Killers. I like that it’s readily available and when used safely and according to instructions, gets rid of most of the worst weeds in anyone’s garden. I recommend this over any other weedkiller and remember it’s the weedkiller I personally use and always have available, that’s why it’s my top recommendation.
2. Roundup Tough Weedkiller
Best Weedkiller For Tree Stumps and Woody Plants
Roundup Super Concentrate Tough Weedkiller is ideal for eliminating tougher, deep-rooted weeds like brambles, thistles, nettles, and couch. Most other weed killers can’t handle this type of growth. This also means that Roundup Super Concentrate deal with tree stumps as well as woody shrubs.
This is a non-selective weed killer so is additionally good for clearing areas such as unwanted vegetation on paths, drives, gravel areas and so on. But don’t use this on your lawn unless you want to kill all the grass wholesale.
[If you are having problems with weeds on your lawn, we have just the review for that.]
Being a systemic weed killer, Roundup Super Concentrate Tough Weedkiller kills tough weeds down to the roots, ensuring that they do not grow back. Be aware that the effects start to show after 48 hours when you will see yellowing of the leaves and stem. Don’t be impatient and think that nothing’s happening in the first day or so. However we don’t recommend removing the weeds for at least seven days to ensure that the weed killer has passed down to all the roots.
The 1 litre super concentrate formula we reviewed treats a maximum area of 90m2 so gives you plenty of coverage even on fairly large areas. However, some online reviewers state that they had to use more than the recommended concentration of solution to water to obtain any results.
If the product is used for the light treatment of annual weeds, replanting and sowing can begin the day after application which is useful, especially for those with allotments. The weed killer becomes inactive as soon as it hits the soil which is environmentally friendly. The product is easily broken down by micro-organisms in the soil to allow replanting.
But if applied to areas with dense cover including perennial weeds, then allow about seven days for the systematic action to reach deep into the roots before digging or cultivating.
Application can be done by sprayer or a watering can that’s fitted with a very fine hose. We always recommend using a sprayer if possible as the diluted weed killer goes a lot further.
Please keep kids and pets out of treated areas until the weed killer has dried on leaves for safety reasons and in order to avoid transfers to the lawn. And be sure to rinse the sprayer at least three times thoroughly after application.
- Systemic weed killer so kills off weeds down to the roots; the weeds don’t grow back at all.
- Best for tough, woody weeds so you can get rid of your brambles, nettles and thistles.
- Yellowing of stems and leaves starts after 48 hours so don’t be too impatient to see the start of the process.
- If applied lightly to weeds, you can start planting in the same spot the next day to multitask your garden.
- Biodegradable by the soil microorganisms so doesn’t hang around to pollute your garden.
- Non-selective weed killer.
- Need more than 30mL of concentrate per L water.
Roundup Super Concentrate Tough Weedkiller is one in a line of well-regarded weed killers from the Roundup company. This version is intended for tougher weeds, and especially woody plants including brambles, nettles, newly cut tree stumps, bracken, and deeply rooted perennials. One advantage of this weed killer if that you can plant after 24 hours of giving the weeds a light application of the solution.
We’ve made Roundup Super Concentrate Tough Weedkiller our choice for the Best weed killer for tree stumps and woody plants. If these are the main types of weeds that are bugging you, this is the weed killer for you.
3. Rootblast Super Concentrated Weed Killer Commercial Strength Glyphosate
Rootblast Super Concentrated Weed Killer is another industrial-strength weed kille that contains glyphosate. As such, it’s non-selective in what it attacks so keep it clear of your lawn and any other plants that you wish to continue growing.
That said, this weed killer works very well on the usual annual and perennial weeds that the other products in our review also deal well with. It’s also great with the woody plants inlcuding docks, nettles and willowherbs. Your broadleaf and grass weeds are also in danger from this weed killer.
What sets this Rootblast weed killer apart from the others is that it has a high concentration of the active ingredient of glyphosate. At 360g/l, this extrastrong concentrate can cover 1,666m2 of weedy landscape per 1L bottle of concentrate when it’s diluted at the recommended ratio.
This is another weed killer with which you have to be patient after application. Signs of its progress, susually shown by the yellowing of leaves and stems, may not appear for up to two to four weeks or even longer. Don’t assume that nothing is happening before this time and reapply the product. Sit back, wait and get on with the other gardening choures that are always waiting to be done.
- Glyphosate weed killer controls deep-rooted perennial and annual weeds as well as woody weeds with commercial strength concentrate.
- Good also for broadleaf and grassy weeds, so most weed types are covered.
- Highly concentrated formula so even your toughest weeds are susceptible to this weed killer.
- Covers up to 1,666m2 of weedy areas.
- Can take up to four weeks to see any yellowing of leaves.
- Non-selective weed killer.
The Rootblast Super Concentrated Weed Killer Commercial Strength Glyphosate is similar to some of our other selections in this review in that is kills both woody and broadleaf weeds effectively. However, the Rootblast product has a high concentration of the active ingredient, glyphosate, which allows it to cover a large area at the recommended dilution. If you do have a large out-of-control area of these weeds, a purchase of this weed killer may be enough to solve your problem.
4. Resolva Xtra Tough Concentrate Weed Killer
The Resolva Xtra Tough Concentrate Weed Killer is another weed killer that’s effective on annual and deep-rooted perennial weeds. However, the Resolva’s specialty is broad-leaved weeds such as creeping thistle and annual sow thistle. The manufacturer claims that this product has enhanced killing performance because of the IQ technology which utilises the speed of a contact weed killer plus the deep root penetration of a systemic weed killer. We’re not sure that this weed killer is any more advanced than the other weed killers on our list. But it does work if you apply it properly at the right time of year.
Just like our previous two recommendations, this weed killer is also biodegradable and is broken down by the microorganisms in the soil. This Resolva product is a systematic, non-selective, and non-residual weed killer. It seeps into any foliage it touches and travels down into the root system where it destroys the growth enzymes. As a result, it kills the weed and prevents future growth which is what helps makes it so effective.
The best time to apply this weed killer is between between late March and early September when the weeds are actively growing. As always, avoid application on lawns and be careful not to spray the weed killer on areas in which you don’t want to kill anything green. The scope of this weed killer includes common nettle, cleaves, curled dock, creeping buttercup, scotch thistle, and many more. Note that signs of progress in some tough weeds may not appear for up to four weeks after application, so don;t just assume that nothing is happening.
Resolva Xtra Tough Concentrate Weed Killer comes in a variety of sizes. The 1 litre bottle size we reviewed is ergonomically designed with finger grips on one side to ensure you have a firm grasp and don’t drop it. This weed killer is affordable and also available in a 200ml bottle or 6 x 100ml sachets . As with most liquids, the larger bottles offer better value for money.
- Systematic weed killer process crossed with a contact weed killer process for enhanced results.
- Good especially for broad-leaved weeds so say goodbye to your creeping thistle and annual sow thistle.
- Excellent for killing off everything within a large area overridden with weeds.
- Non-selective so kills whatever foliage it touches.
- May take up to four weeks to show signs of any progress.
Resolva Xtra Tough Concentrate Weed Killer kills most domestic weeds but is especially great for eliminating an area overridden with unwanted weeds. Its specialty is dealing with broad-leaved weeds including docks, thistles, nettles, creeping buttercup, dandelion and other deep-rooted unwanted plants.
If your weeds contain many with broad-leaves or you have a large weed patch at the bottom of your garden, this weed killer might just do the trick.
5. Vitax SBK Brushwood Killer Tough Weedkiller
The Best Weedkiller For Killing Everything But Lawns
At first sight, Vitax SBK Brushwood Tough Weedkiller is similar to the Roundup Super Concentrate Tough Weedkiller we reviewed earlier. They both deal very well with woody weeds such as brambles, thistles, nettles, dock, ivy, hardwood saplings, and tree stumps. But there is one very big difference: Vitax SBK Brushwood Tough Weedkiller does NOT harm grass. That’s right, this product won’t kill off your lawn.
The reason is that the Vitax SNX product contains triclopyr and not glyphosate. Triclopyr is effective on woody plants and broadleaf weeds, but it does not affect grass. This makes Vitax the only weed killer on our list you can use without having to worry about killing your lawn. You can even use it on your lawn if you have lots of weeds there too; it’s especially good for violets. This is still a systemic weed killer that gets right down into the roots to destroy the plant.
Vitax does have a residual effect so you can expect the spray to linger in the soil for a few weeks after application. This does stop you from planting in the area straight away. The active ingredient is biodegradable with a half-life of 60 days, but it remains active in dead vegetation for up to 90 days. As such, this weed killer must be applied at least six weeks before re-cultivating or sowing.
The best time to apply Vitax to hardwood saplings and tough weeds is from around May to October when the soil is moist. Woody weeds respond best to treatment from June to August, whilst tree stumps respond well between autumn and winter when the sap is retreating downwards.
Although it doesn’t kill lawns, we do not recommend using this on newly-turfed lawns. Lastly, this weed killer is available at a good price and it comes in 125ml, 250ml, 500ml bottles and 1 litre bottles of concentrate.
- Selective triclopyr weed killer especially suited for brushwood and woody plants so your brambles, nettles and newly cut tree stumps will bite the dust.
- Equally effective against broadleaf weeds and particularly so against the ubiquitous Creeping Charlie.
- Grass is not harmed so your lawn is safe from accidental spraying or even when you use this to get rid of weeds from there.
- Effective use for brush control so you can clean out your straggly bushes.
- Needs six weeks between application and replanting.
Vitax SBK Brushwood Tough Weedkiller does what you want and doesn’t do what you don’t want. It kills woody weeds and tree stumps, and also works well on broadleaf weeds. It’s effective if you want to clear brush from the hidden parts at the end of your garden. But it doesn’t harm your grass. Use this close to the lawn without worry. Or even use it to remove weeds from within your lawn. One downside is the length of time (six weeks) you have to wait before applying the solution and replanting.
If you plan carefully, this weed killer could get rid of most of the many types of weeds you have, wherever they are in your garden
Types of chemicals
Most weed killers used by professional gardeners to treat commonly used areas around buildings, large areas of beds and borders as well as on paths and car parks have one thing in common. All the professional weed killers we review come in concentrated form. This means that you have to dilute them by adding a certain volume of the concentrate to a certain volume (usually 1 litre) of water. Each weed killer can have a different ratio of concentrate to water, so always check the instructions on your bottle of product.
Most commercial-grade weed killers are glyphosate-based. Each brand may have a different concentrate of this ingredient in it, so always check what’s written on the label of the bottle. The higher the percentage of glyphosate given, the higher the concentrate. You can find this ingredient in domestic weed killers but at a much lower concentration.
Glyphosate weed killers kill through a systemic progress. This means that the liquid enters the leaves of the plant and works its way down through the plant’s entire internal system, all the way down to the roots. The glyphosate is the poison, and it kills every part of the plant from the inside, from the leaves down to the tips of the root.
Glyphosate weed killers are bio-degradable. This means that the liquid becomes inactive once it touches the soil and the microorganisms within the soil degrade it into natural materials, rendering it harmless.
These types of weed killers are best suited for broadleaf weeds as well as grass weeds.
Triclopyr-based commercial-grade weed killers are selective which means that they kill nearly everything EXCEPT grass. We include one of these products, the Vitax SBK Weedkiller, for those home gardeners who are haunted by the weeds in their otherwise lush and magazine-worthy lawns.
Making up the correct concentration
Review the instructions on your weed killer bottle or box for the correct dilution ratio to use the first time you use the weed killer. On subsequent times, after you’ve seen the results of your first applications, you may want to change the ratio to a more concentrated or more dilute solution.
Follow the instructions also about where to mix the concentrate and water; it’s usually in a watering can or jug reserved exclusively for this purpose. Even if you rinse it out thoroughly after mixing everything, there may still be some solution left that could end up somewhere you don’t want it. And wear gloves and eye protection and other safety gear to guard against any splashes on to your skin.
How to apply
You can usually apply your weed killer solution using a sprayer or a watering can with a very fine nozzle. However, we always recommend that you use the sprayer as it distributes the solution more evenly and more finely, making the liquid go further. And don’t use the sprayer for anything else, even after you’ve thoroughly rinse it three times at the end of the application task. However, always read the instructions thoroughly on the container before use and apply only as directed.
Be sure to always wear protective gloves, mask and goggles for your own safety. And don’t let any of the spray go into your garden pond or any nearby stream or river. It could contaminate them and harm the fish and water plants growing there.
When to apply the weed killer
Once again, always read the instructions. But it’s the general rule to apply commercial-grade weed killer in the weed’s active growing season, usually between March and September. As the weed killer works systemically and needs to travel through the plant’s entire system, the plant has to be active and not dormant such as in late fall or winter.
Don’t spray on a windy day or if rain is forecast within the next six to eight hours.
I’ve tried domestic weed killers and even some industrial strength ones, but my Japanese Knotweed just won’t go away. What’s next?
Many people ask what can kill Japanese knotweed. The usual answer is a glyphosate-based weed killer and patience. Any of the glyphosate-based products in our review can do the trick. Just be prepared to re-spray when the Knotweed returns as it can take a few years before it can be completely killed off. Professional companies treat areas with this weed for around five years when treating large area, so one spray will not have much effect. For some weeds, single applications of weed killers don’t work miracles; you have to hang in there are keep re-treating them.
Should I reapply the weed killer if nothing happens?
Are you sure that nothing is happening? The most common critique we came across during our research for this review was that the weed killer didn’t work. And we found this for every weed killer. If you read the instructions/information for your weed killer, it will say that you may see signs of decay in two days to a number of days or weeks.
Some weed killers don’t show outward signs of work until several weeks or longer after application. But even though the leaves and stem of the weeds aren’t yellowing, the poison may be working on the plant’s internal system, making its way down to the roots and out to the tips of the leaves. Just wait longer and see what happens.
If you’ve waited and still nothing happens, there may be reasons that the weed killer hasn’t worked. Did you apply it in the plant’s seasonal active period? Was the solution concentrated enough? Did it rain within eight hours of application and so wash the weed killer away? Fix the problem if possible (except if the weed is dormant) and reapply the solution.
There are a lot of weedkillers available, yet we only really recommend 5 different weedkillers. Our top recommended and probably the most effective is Gallup Glyphosate Weedkiller, it’s probably the strongest weedkiller available to the average person.
If domestic weed killers just haven’t made a dent in some of your toughest weeds, and you’ve given it enough thought, professional-grade weed killers may be your next step. Most of the products we review are glyphosate-based, meaning that they kill things other than weeds, such as your lawn. Only the single triclopyr-based weed killer won’t harm your grass, yet will kill almost everything else. Choosing the best commercial-strength weed killer for your needs isn’t difficult but does require some thought.
Our Best Pick of the strongest weed killers is the Gallup Glyphosate Weedkiller. This is one of the strongest products available for the domestic gardener. It’s versatile as to the weeds it kills and will kill your lawn if you get any on your grass.
The Roundup Super Concentrate Tough Weedkiller is our choice for Best Weed Killer for woody weeds and tree stumps. It’s also based on glyphosate but is very effective for brambles, nettles and dandelions. But once again, beware your grass.
We have to mention here our only choice that won’t harm your grass, but kills pretty much anything else. The Vitax SBK Brushwood Tough Weedkiller is safe to use on your grass yet it’s powerful enough to clear large areas of brushwood.
If you decide that an industrial-strength weed killer is not really what you need, our review on the Best Weed Killers for Driveways may be of interest. Or if you have little ones running around your garden all the time, how about our Best Pet Friendly Weed Killer article?
Last update on 2021-10-15 / Affiliate links / Images from Amazon Product Advertising API