5 Strongest Industrial Weedkillers – Kills Everything & Professional Grade

When it comes to the strongest weedkillers, there are a handful of very effective professional-grade weedkillers that I have been using as part of my garden maintenance business. The problem is that most require a spraying chemical licence to purchase. However, they are not available to the general public and can be expensive. Now, although I have a recognised 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, that doesn’t mean you have to settle for a less effective weedkiller!

One thing most professional-grade weed killers have in common is that they contain a high concentration of glyphosate, the main ingredient. Now, glyphosate is in most weedkillers; the problem is that many domestic weedkillers contain a very weak dose of glyphosate; it’s actually the amount of glyphosate that matters.

To give you an idea, Gallup Weedkiller and Rootblast, my two favourite glyphosate-based weedkillers and both perfect for killing weeds on driveways as discussed here, contain 360 grams of glyphosate per litre of weedkiller concentrate, which you can read on the label as pictured above. Now, compare this to off-the-shelf weedkillers, such as Roundup Fast Action Weedkiller, a popular weedkiller sold at garden centres. This only contains 7.2 grams of glyphosate per litre of weedkiller concentrate. They’re not even comparable, which is why you see such bad reviews for weedkillers online.

I’ve been in the gardening industry for over 20 years, running my own garden maintenance business and working in the family nursery. Because of my experience, I have used 2-3 of the strongest weedkillers that I would discribe as ‘professional grade weedkillers’ and, somehow, are still available to the general public. The main reason I use these alternatives is the price; they are generally more affordable!

My two go-to strongest weed killers are Gallup Home & Garden Weedkiller, and the second I’ve started using more recently is Rootblast Super Strength Weedkiller because Gallup was sold out, both of which are pictured above. Both of these weedkillers contain 360 grams of glyphosate per litre of weedkiller concentrate (360 g/l). This is the highest concentration of glyphosate you can get, even professional-grade weedkillers that you need a license to purchase, which only contain 360 g/l.

Now, the only difference between the Gallup Home & Garden weedkiller and Rootblast weedkiller is you mix Gallup Home & Garden Weedkiller at 24ml of concentrate per litre of water, and you mix Rootblast Super Strength Weedkiller at 15ml of concentrate per litre of water, so the recommended mix is slightly weaker. However, I have found the results to be very similar to those of Rootblast; it just takes slightly longer for results to show.

Before I get into the more detailed reviews further down and show some results, I want to point out that I always try, where possible, not to use these chemical weedkillers. I always try to prevent weeds first, which I talk about here. I also regularly use a decent weed puller, such as my Gardena weed puller, especially on lawns, and I also use a selection of different weeding tools.

On my customer’s lawns, I make sure I use a selective weedkiller that kills the weeds but not the grass, as well as maintaining the lawn with a scarifier and lawn aerator. Doing this also helps control weeds.

A quick word about applying these concentrated weedkillers. For them to be effective, always apply when the weeds are actively growing and apply to fresh green foliage. Read the label/container and apply as instructed. I like to use a garden sprayer, which I only use for spraying weedkillers; I usually use a knapsack sprayer, which includes my Hozelock knapsack sprayer at home or my Cooper Pegler Classic CP15 15L Knapsack Sprayer pictured above for professional jobs.

Sometimes, my customers are not comfortable with my spraying glyphosate-based weedkillers. They may have pets, and although areas treated with glyphosate weedkillers are safe for pets and children once the treated area is dry, some of my customers are just not comfortable with it. In these cases, I usually use a weedkiller called WeedKil Fast Acting Weed Killer, pictured above, which I also review in my pet-friendly weedkiller guide.

It’s an organic weedkiller made from acetic acid, commonly known as vinegar. It’s super safe and very effective, and you even see results within a few hours (not days or weeks). The problem is it doesn’t kill the roots, and larger perennial weeds do grow back. However, I like to use it to keep on top of weeds on driveways, where I can spray the weeds every couple of weeks while there are still seedlings as part of the garden maintenance. It just knocks them back and keeps the drive looking great.

Strongest Weed killer Review

1. Gallup Home & Garden Glyphosate Weedkiller

Best Pick

Gallop Glyphosate Weed Killer is probably the closest you will get to a professional-strength weedkiller. Along with Rootblast, which I talk about next, they are both available for industrial use and are by far the best weedkiller that the general public can use. While many weedkillers have been banned over the years, Gallop has somehow avoided this, at least for now, and anyone can still buy it. You won’t find a better weedkiller!

Now, I will start by saying this is the only weedkiller I use; it’s 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, it can damage the environment and have serious consequences.

To demonstrate how effective this weed killer is, I recently sprayed a large area with some very tall established weeds. Now, in general, you want to spray weeds as they emerge so they’re 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 from before I treated the area with Gallup Home & Garden weedkiller at the recommended concentration. 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 that it’s been very effective.

Gallop does kill most annual and deep-rooted perennial weeds and grasses. It will also usually kill a mare’s tail, which I recently tested at a friend’s house who has had some issues with it. 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 recommend 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 will actually buy the 2-litre container as it goes a long way, and this will be more than enough for most people.

Pros

• Glyphosate Weed Killer that can be used in aquatic environments such as around ponds as well as in the usual flower beds.
• It 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 the 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, it is somewhat environmentally friendly.

My recommendation

For good reasons, Gallop Glyphosate Weed Killer is one of the most popular industrial-strength weed killers. 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 my review of the Strongest Weed Killers. I like that it’s readily available online and is very effective at killing weeds when used safely and according to instructions. I recommend this over any other weedkiller, and remember, it’s the weedkiller I personally use the most and always have available, so that’s why it’s my top recommendation.

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2. Rootblast Super Concentrated Weed Killer

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I just had to include Rootblast Super Concentrated Weed Killer, as I’ve personally used this over the last couple of years, and it’s as good as Gallup. It is another industrial-strength weed killer that contains a high ratio of glyphosate. Just remember it’s non-selective in what it attacks, so keep it clear of your lawn and any other plants, but this goes for all the weedkillers in my guide.

That said, this weed killer works very well on the usual annual and perennial weeds that the other products in my review also deal well with. It’s also great with woody plants, including docks, nettles and willowherbs, making it a good choice for large areas of overgrown brush such as nettles, thistles and most other hard-to-kill weeds.

What sets this Rootblast weed killer apart from most other weedkillers, like Gallup home & Garden Weed Killer, 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 of concentrate when it’s diluted at the recommended ratio.

Signs of its progress, usually shown by the yellowing of leaves and stems, usually take up to two to four weeks or even longer. What I’m saying is don’t assume that nothing has happened before this time. Its takes a little while to take effect but its extremely effective as it kills the roots and foliage.

Pros

• 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.

My recommendation

Rootblast Super Concentrated Weed Killer Commercial Strength Glyphosate is similar to some of my other recommended weed killers 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, this weed killer will be very effective and possibly slightly more value for money than Gallup, as it’s applied at a slightly lower rate while still retaining its effectiveness.

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3. Roundup Tough Weedkiller

Best Weedkiller For Tree Stumps and Woody Plants

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If you’re looking for a weed killer you can probably pick up at your local garden centre, then this Roundup Super Concentrate Tough Weedkiller is probably the one to go for. Ideal for eliminating tougher, deep-rooted weeds like brambles, thistles, nettles, and couches, it’s expensive but very effective. Most other weed killers you find at garden centres can’t handle this type of growth. This also means that Roundup Super Concentrate deals with tree stumps as well as woody shrubs. It’s a good alternative to Gallup and Rootblast if you are looking for a weedkiller more marketed towards the domestic market.

This is a non-selective weed killer, so it is also good for clearing areas such as unwanted vegetation on paths, drives, gravel areas, and so on.

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 around 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, I don’t recommend removing the weeds for at least seven days to ensure the weed killer has passed down to all the roots.

This comes in a 1-litre super concentrate formula and treats a maximum area of 90m2, so it gives you plenty of coverage even on fairly large areas. 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.

The application can be done by garden sprayer or a watering can that’s fitted with a very fine hose. I always recommend using a sprayer if possible, as the diluted weed killer goes a lot further when applied with a sprayer.

As always, please keep kids and pets out of treated areas until the weed killer has dried on leaves for safety reasons and to avoid transfers to the lawn. Be sure to rinse the sprayer at least three times thoroughly after application. I always recommend having a separate sprayer for weedkillers than you use for pesticides.

Pros

• A systemic weed killer kills 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.
• The yellowing of stems and leaves starts after 48 hours, so don’t be too impatient to see the process start.
• 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 don’t hang around to pollute your garden.

My recommendation

Roundup Super Concentrate Tough Weedkiller is a well-regarded weed killer from the Roundup company. This version is the best as it’s 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 in treated areas after 24 hours of giving the weeds a light application of the solution.

I’ve made Roundup Super Concentrate Tough Weedkiller my choice for the Best weed killer for tree stumps and woody plants, but you can apply it differently for tree stumps. Do make sure you read the instructions.

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3. Resolva Xtra Tough Concentrate Weed Killer

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Resolva Xtra Tough Concentrate Weed Killer is another weed killer that’s effective on annual and deep-rooted perennial weeds that are available at most garden centres. However, the Resolva’s speciality is broad-leaved weeds such as creeping thistle and annual sow thistle. I believe this weedkiller 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. If I’m honest, I’m not sure that this weed killer is any more advanced than the other weed killers, but it does work if you apply it properly at the right time of year when new growth is fresh.

Just like my three previous 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 makes it so effective.

The best time to apply this weed killer is 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 I 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 available in a 200ml bottle or 6 x 100ml sachets for even easier measuring and mixing. As with most liquids, the larger bottles offer better value for money.

Pros

• 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.

My recommendation

Resolva Xtra Tough Concentrate Weed Killer kills the most common weeds but is especially great for eliminating an area overridden with unwanted weeds. Its speciality is dealing with broad-leaved weeds, including docks, thistles, nettles, creeping buttercups, dandelions 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.

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5. Vitax SBK Brushwood Killer Tough Weedkiller

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Vitax SBK Brushwood Tough Weedkiller is what we used to use in the nursery before we used Gallup and Rootblast. It’s similar to the Roundup Super Concentrate Tough Weedkiller I reviewed earlier. They both deal very well with woody weeds such as brambles, thistles, nettles, dock, ivy, hardwood saplings, and even 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 like all the other weedkillers. Triclopyr is effective on woody plants and broadleaf weeds, but it does not affect grass. This makes Vitax the only weed killer on my 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. This is still a systemic weed killer that gets right down into the roots to destroy the weed.

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, which is why, in the nursery, we switched to Gallup.

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, I 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.

Pros

• 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 you can even use this to get rid of weeds.
• Effective use for brush control so you can clean out your straggly bushes.

My recommendation

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

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Weed killer Buyer’s Guide

Types of chemicals

Most weed killers used by professional gardeners like myself 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 I 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. You can even vary the concentration level depending on how established and hard to kill the weeds are.

Glyphosate-based weed killers

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 concentration. 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

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.

Application

Making up the correct concentration

Review the instructions on your weed killer bottle or box for the correct dilution ratio to use the weed killer the first time. 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 if the instructions on the label allow.

Follow the instructions 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 thoroughly after mixing everything, some solution may still be left that could end up somewhere you don’t want it. Wear gloves, eye protection, and other safety gear to guard against any splashes on your skin.

How to apply

You can usually apply your weed killer using a sprayer (like me) or a watering can with a very fine nozzle. However, I always recommend that you use the sprayer, as it distributes the solution more evenly and finely, making the liquid go further. Don’t use the sprayer for anything else, even after you’ve thoroughly rinsed it three times at the end of the application task. Always read the instructions thoroughly on the container before use and apply only as directed.

Be sure to always wear protective gloves, masks and goggles for your 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 autumn or winter.

Don’t spray on a windy day or if rain is forecast within the next six to eight hours.

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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 my 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.

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Final Conclusion

There are a lot of weedkillers available, yet I only really recommend five 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 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. The single triclopyr-based weed killer won’t harm your grass, yet it will kill almost everything else. Choosing the best commercial-strength weed killer for your needs isn’t difficult but does require some thought.

My 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 my choice for the Best Weed Killer for woody weeds and tree stumps. It’s also based on glyphosate but is very effective for brambles, nettles and dandelions.

I 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 powerful enough to clear large areas of brushwood.

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Last update on 2024-11-19 / Affiliate links / Images from Amazon Product Advertising API