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5 Best Herbicides for Thistles

Best Herbicides for Thistles

Most recommended
Southern Ag Southern Ag CROSSBOW32 Weed & Brush Killer
  • 1 Quart
  • Non-crop areas
  • 4 to 6 fl.

A good choice too
PBI/Gordon 652400PBI/Gordon 652400 Speed Zone Lawn Weed Killer
  • Rapid and effective
  • Visible results in hours
  • Covers from 14K to 18K sq. ft

A good choice too
RM18 Fast-Acting
RM18 Fast-Acting Weed & Grass Killer Herbicide
  • No Assembly Required
  • Visible Results In 12 Hours
  • Treats Up To 3, 000 sq. ft

Image 100099405Image 100099405 Kills Nutsedge Concentrate
  • 24 Ounce
  • Treats 6000 sq. ft.
  • Manufactured in US

Gordon QT TrimecPBI/Gordon QT Trimec Lawn Weed Killer
  • Economical choice
  • Covers 32,000 to 64,000 sq. ft.
  • 3-way herbicide blend

Choose the Best Herbicides for Thistles

Customer’s Choice: the Best Rated Herbicides for Thistles

222 users answered this survey. Please help us improve this review!

65.32% of users selected Southern Ag, 5.41% selected PBI/Gordon 652400, 12.16% selected RM18 Fast-Acting, 3.15% selected Image 100099405 and 13.96% selected Gordon QT Trimec. Every month we analyze your answers and change our rating.

Canada thistle (a.k.a. Cirsium arvense or just thistles) is probably one of the most invasive plants in the home garden and has a reputation for being difficult to get rid of. It is difficult to manage Canada thistle and takes a considerable amount of work to succeed, but when you have a field/lawn/garden that is clean of this irritating plant, the effort you put into managing Canada thistle will pay off.Canada thistle is an annual weed with strongly lobed, spear-like, soft green leaves, and these leaves have small barbs on them. The flower resembles a purple poof-ball that will be formed at the top of the plant in clusters if permitted to go to flower. The flower would turn white and fuzzy, just like a dandelion seed head, if the flowers were approved to go to seed.

Using sustainable approaches, organic herbicides, or artificial herbicides, you may get rid of most thistles. The following guide focuses on the best herbicides for thistles control available in the U.S. market. The major specs are included in the comparison table below. Also, please read the buyer’s guide to learn more about the chemical solutions for killing thistles.

Southern Ag CROSSBOW32 Weed & Brush Killer – the best for non-crop areas!

Southern Ag CROSSBOW32 Weed & Brush KillerMost unwanted trees and brush are managed by Weed & Brush Killer by Southern Ag. It can be used near your home on rangeland, grass pastures, and other non-crop lands.

If you’d like to use mild brush herbicides in the flower beds, it is very appropriate. Within a few days, you will destroy any of the broadleaf weeds along the fences and roadsides. Butoxy-ethyl is used as an active component in it.

  • Can cope with most weeds;
  • Affordable;
  • The long-term effect;
  • Has to be used carefully in summer;
Especially in comparison to many other weed killers, it is really powerful if you choose to destroy difficult plants like poison ivy, horsetail and Creeping Charlie.

PBI/Gordon 652400 Speed Zone Lawn Weed Killer – the best for the coverage area!

PBI/Gordon 652400 Speed Zone Lawn Weed KillerA fast-acting chemical will soon liberate your garden from weeds. Those speedy weed killers, though, quite sometimes end up killing the lawn.

Therefore, this Gordon 652400 weed killer is what you need if you are searching for the right spray for lawns that has no other impact on your turf.

It just acts on the leaves of the weeds, ensuring that plants like grass are not affected. This SpeedZone product can easily leave you with a desirable lawn swept out of weeds. You will start seeing the improvements within a couple of hours.

Also, you can decide on this herbicide if you have a considerably wide lawn, as it will cover from 14,000 and 18,000 sq. ft. of land. Therefore, for covering a large-scale lawn, only one bottle of this substance is appropriate.

  • Covers the large area;
  • Acts quickly;
  • Won’t harm the lawn grass;
  • Only for the cool climate;
  • Restricted in some American states;

Therefore, if you’re searching for a herbicide that you can use on the most vigorous weeds on a large-scale yard, then seek no further than this Gordon’s herbicide.

RM18 Fast-Acting Weed & Grass Killer Herbicide– the best for quick performance!

RM18 Fast-Acting Weed & Grass Killer HerbicideConsider opting for a fast-acting chemical, such as the RM18 Herbicide, while destroying oxalis in flower beds. This killer of the oxalis flower bed will remove all weeds and grass from your flowerbed.

The manufacturer suggests wetting your goal weed leaf roots and leaves with RM18 to quickly destroy all the oxalis on touch.

While being an excellent eradicator of oxalis, suggest cleaning your mouth vigorously with running water if RM18 interacts with your mouth.

RM18 will destroy oxalis in a yard or lawn, or around 3, 000 sq. ft., with 18% of the total ingredient as glyphosate. Just ft. In addition, as the glyphosate component present gives noticeable effects in the first 12 hours after applying, RM18 is a quick-acting herbicide.

  • A very concentrated formula;
  • The first results appear in 12 hours;
  • Simple to use;
  • Pet-friendly;
  • Non-selection action;

Other important ingredients in RM18, such as salts and diquat dibromide, increase its effectiveness, rendering it an efficient herbicide in flower beds to destroy thistles, wild blackberry, kudzu, poison ivy, poison oak, and crabgrass.

Image 100099405 Kills Nutsedge Concentrate– the best for formula!

Image 100099405 Kills Nutsedge ConcentrateThis post-emergent herbicide can be used on southern turf grass and chosen ornamentals. It can be extended during the year. Its proprietary one-of-a-kind formula operates by inhibiting the photosynthesis mechanism of the weeds, which effectively starves them to death.

After a few hours of application, growth inhibition occurs, with yellowing taking place 1-2 weeks away. Within 3-5 weeks, the full effects are shown.

The hardest southern plants, including yellow and purple nutsedge, dollar vine, wild onion and annual bluegrass, can be killed with this Image herbicide. The substance can be easily used on most southern grasses as well.

  • Safe for pets;
  • Applied year-round;
  • The large coverage area up to 6,000 sq. ft.;
  • Limited for sale in some states;
  • A bit complicated to use;
  • Won’t cope with cool-season grasses;

Use this concentrated chemical formula to give your lawn the look without the weeds. For use in southern turf grass and chosen ornamentals, this herbicide is one of the best picks.

PBI/Gordon QT Trimec Lawn Weed Killer– the best for the cool season!

PBI/Gordon QT Trimec Lawn Weed KillerFor any household, this weed killer offers the protection from a wide range of broadleaf weeds. It destroys lawn weeds that are hard to handle. It was built for cool seasonal grass applications.

One of the most concentrated formulas in the market. You should blend it with water. Bear in mind that up 1 quart may treat 8000 sq. ft.

  • Very concentrated;
  • Will cope with cool-season grasses;
  • Spot spraying;
  • Controls over 250 weeds;
  • Difficult for mixing and using;
  • Only for grassy lawns;

For DIY fans, this liquid could be a perfect choice. The budget-friendly alternative is for you if you are comfortable combining and spraying herbicides. As well as 250+ other lawn weeds, this product does a fine job of suppressing crabgrass.

The Buyer’s Guide

What thistle species can be treated with herbicides:

  • Cirsium arvense a.k.a Creeping thistles;
  • Cirsium vulgare is also known as Spear and Marsh thistles;
  • Onopordum acanthium is known as Scotch thistle;
  • Silybum is Milk thistles;

Active components

Glyphosate. On young thistle seedlings, glyphosate can have a positive impact, but it is not ideal for paddock conditions where a specific herbicide is much needed. This form of weed killer specifically attacks the weeds, but other plants that are near the weed typically do not destroy it. For flower beds and barriers that have thistle sprouts, this allows it a perfect option. If you want to deal with a plot without destroying the other plants, use this weed killer.

One of the country’s cheapest and most popular weed killers has a label that you’ve actually never heard before: 2,4-D. By having the cells of the undesirable plant develop out of reach this chemical may kill not only grasses, but also fruits and vegetables, may target both the roots and leaves of weeds. 

It is commonly used in the fields of soybean, maize, sugarcane, and wheat in cultivation, and it occurs in most items of “grass and feed” as well as in certain lawn treatments. The thing is, under today’s criteria, the herbicide that was once deemed clean and green might not be healthy anymore.

Application timing

The period from March to May is one of the best ones to apply Glyphosate, clopyralid, or Aminopyralid to control thistles. The perfect time to apply this is when the temperature range is between 65 and 85F on sunny days.

Because many herbicides are non-selective, everything they hit would be killed, so it is better not to use them on windy days. If you need to handle thistles where the plants you want are closer, you could be best off painting the weed killer on most thistles with a paintbrush.

What areas have to be treated?

Thistles are among the weeds that are mostly reviled but are readily identifiable. Lawns, grassland & paddocks can be overrun quickly. 

All of the key spots for thistle development are grassland fields, path edges and uncultivated soil. As a protection mechanism toward grazing herbivores, thistles have established their spiky leaves and may swamp a grazing paddock or lawn quickly-out-competing grass and limiting usable forage.

By reducing the numbers in a field, digging/ dragging out thistle weeds will function for new paddocks. Soft soils are needed to complete the treatment after rain, though, and there is also the possibility of leaving behind delicate root fragments to re-grow.


Is there a specific time of year when you should apply herbicides for thistles?

Herbicides for thistles can be applied any time of year. However, it is important to note that they will be most effective when the plants are actively growing. This means that you should apply them in early spring or late summer/early fall.

Applying herbicides during these times will ensure that the plants are absorbing the chemicals and that they are being effective. If you apply them during periods of dormancy, the plants will not be able to absorb the herbicide and it will be less effective.

Which Roundup is best for thistles?

The best Roundup for thistles is the one that suits your needs the most. If you have a large area to cover, then you may want to consider a concentrate. However, if you only have a small area to treat, then a ready-to-use product would be more suitable.

There are many different types of herbicides on the market, so it’s important to do your research and choose the one that will work best for your specific situation. You should also take into account the time of year and the stage of growth of the thistles when deciding which herbicide to use.

How long does Roundup take to kill thistle?

Roundup is a very effective herbicide that will kill thistles quickly. However, to avoid harming other plants or animals, it is critical to follow the instructions on the Roundup label meticulously. Roundup usually takes about 24 hours to kill thistles.

If you have a thistle problem that is particularly difficult to control, you may want to consider using a stronger herbicide. Glyphosate-based herbicides are among the most effective for killing thistles. These products usually take about 48 hours to kill thistles.

Of course, no matter what type of herbicide you use, it is important to follow the directions on the label carefully in order to avoid harming other plants or animals.

How many ounces of Roundup will kill thistle?

The amount of Roundup needed to kill thistle depends on the size and age of the plant. For example, it takes about four ounces of Roundup to kill a one-year-old thistle that is six inches tall. To be safe, always follow the label directions when using any herbicide.

Roundup comes in both liquid and granular form. The liquid form is more concentrated and will work faster, but the granular form is easier to apply. If you choose to use the granular form, make sure you water it in well so that it can reach the roots of the plant.

Roundup can be applied either with a pump sprayer or a hose-end sprayer. If you are using a pump sprayer, you will need to mix the Roundup with water according to the label directions. If you are using a hose-end sprayer, you can simply attach the bottle of Roundup to your garden hose and spray it directly on the thistles.

What is the best product to kill Canadian thistle?

The best product to kill Canadian thistle is one that contains glyphosate as the active ingredient. Glyphosate is a herbicide that will kill any plant it comes in contact with, regardless of the species. However, Canadian thistles are very difficult to control and may require multiple applications of glyphosate before they are completely killed.

Roundup Ready-To-Use Weed & Grass Killer III is one glyphosate product that can be used to kill Canadian thistles. You can find it at most home improvement stores, and it comes in a convenient ready-to-use pump sprayer. Roundup products contain other ingredients in addition to glyphosate, so be sure to read the label carefully before purchasing any weed killer.

Another glyphosate product that can be used to control Canadian thistles is Ortho Ground Clear Super Concentrate. This product is a little more concentrated than Roundup and may require the use of personal protective equipment, such as gloves and a respirator, when applying. Ortho products can be found at most home improvement stores as well.

While glyphosate is the most effective herbicide for Canadian thistles, there are other products that contain different active ingredients that can also be used. Triclopyr is another non-selective herbicide that can be used to kill Canadian thistles. Products containing triclopyr include Scotts Turf Builder Weed & Feed and Miracle-Gro Shake ‘n Feed All Purpose Plant Food + Weed Preventer.

Will glyphosate kill thistles?

Yes, glyphosate is an effective herbicide for thistles. Glyphosate will kill thistles by inhibiting their ability to produce amino acids, which are essential for plant growth. Glyphosate is a non-selective herbicide, which means it will kill any plant that it comes into contact with, so be careful when applying it.

If you’re looking for a more targeted herbicide, there are several products on the market that are specifically designed to kill thistles. One such product is “Thistle-Seeded” from Safer Brand. This product contains the active ingredient clopyralid, which is a selective herbicide that will only kill thistles and not other plants.

Another option is “Tumbleweed Killer” from Green Light. This product contains the active ingredient dicamba, which is also a selective herbicide that will only kill thistles.

How do I permanently get rid of thistles?

There is no silver bullet when it comes to getting rid of thistles. The best way to control them is to use a combination of methods including herbicides, physical removal, and preventative measures.

Herbicides are the most common method for controlling thistles. There are many different products on the market, so it’s important to choose one that is specifically designed for thistles. Glyphosate is the active ingredient in most thistle-killing herbicides. It works by translocating through the plant and causing cell death.

When using herbicides, always follow the instructions on the label carefully. This will ensure that you use them safely and effectively.

Does 2,4-D kill thistles?

Yes, products containing the active ingredient glyphosate are effective against thistles. Glyphosate-based herbicides work by killing the plants’ leaves and roots, causing them to die within a few days to a week.

When used as directed, glyphosate products are safe for people and animals. However, they can be harmful if ingested, so it’s important to keep them out of reach of children and pets.

Glyphosate is most effective when applied to young thistle plants that are actively growing. For best results, apply the herbicide in early spring or summer when the plants are in full leaf.

How do you get rid of thistles with vinegar?

One way to get rid of thistles is to use vinegar. You can either buy vinegar at the store or make your own. To make your own, you will need to gather some plants that have thistles on them and put them in a container. Then, pour vinegar over the top of the plants and let it sit for a few days. After a few days, check on the plants and see if the thistles have died. If they have, then you can remove the plants from the container and dispose of them.

Another way to use vinegar to get rid of thistles is to mix it with water and spray it on the plant. This method may take a little longer to work, but it will eventually kill the thistle.

Vinegar is a natural herbicide and is safe to use around children and pets. It is also one of the most affordable options for getting rid of thistles.

Can you spray thistles in the summer?

Yes, you can spray thistles in the summer. However, it is important to choose an herbicide that is specifically designed for thistles. You should also be aware of the potential for drift when spraying herbicides near sensitive areas such as gardens or waterways.

If you are planning to spray thistles in the summer, we recommend using Roundup MAX Control 365 Concentrate. This herbicide is specifically designed to kill tough weeds like thistles, and it has a long lasting formula that will keep them from coming back. Additionally, Roundup MAX Control 365 Concentrate has a built-in wand applicator that makes it easy to apply without worrying about drift.

Can you spray thistle in the fall?

Yes, you can spray thistles in the fall. There are a few things to keep in mind, though. First, the temperature needs to be right. If it’s too cold, the herbicide won’t work as well. Second, you need to make sure the plants are actively growing. If they’re not, the herbicide won’t be as effective.

That said, there are a few herbicides that work well on thistles in the fall. Glyphosate is a good option. It’s available in both liquid and granular form, so you can choose what works best for you. Another option is imazapyr. This one is only available in liquid form, but it’s very effective.

Will Grazon kill thistle?

Grazon is a broadleaf herbicide that is effective in killing thistles. It works by preventing the plant from producing the necessary chemicals for photosynthesis. This will eventually kill the plant. Grazon is a non-selective herbicide, which means it will kill any plants that it comes into contact with. You should be very careful when using this product and avoid spraying it on any plants that you do not want to kill.

If you have thistles on your property, you can use Grazon to get rid of them. The best time to apply the herbicide is in late spring or early summer when the thistles are actively growing. You should follow the instructions on the product label carefully to ensure that you are using it correctly. Grazon is a very effective herbicide and will kill thistles quickly.

Does mowing thistles kill them?

Mowing thistles does not kill them. The thistles will regrow from the root system and continue to spread. Mowing is only a temporary solution to managing thistles.

Herbicides are a more effective means of thistle control. There are several herbicides on the market that will kill thistles. glyphosate is a non-selective herbicide that will kill any plant it comes in contact with. Selective herbicides, such as those containing clopyralid or picloram, are designed to target specific plants, like thistles, without harming other plants nearby.

The best time to apply herbicide to thistles is when they are actively growing in the spring or fall. The leaves of the plant need to be present for the herbicide to be absorbed and translocated throughout the plant. Applying herbicide when the plant is dormant (in winter) will not be effective.

Will dicamba kill thistles?

Dicamba will kill thistles if the plants are actively growing and the herbicide is applied correctly. This broadleaf weed killer can be used as a spot treatment or over-the-top application on most labeled grasses. For dicamba to be effective, make sure to follow all product directions and take care not to damage your desirable plants.

Are there any alternative methods for getting rid of thistles?

Yes, there are several alternative methods for getting rid of thistles. One is to physically remove them from your garden or lawn. This can be done by hand-pulling, hoeing, or using a weed whacker. Another method is to smother them with mulch or plastic. You can also try solarization, which is a process of using the sun’s heat to kill weeds. Finally, you can use herbicides.

Herbicides are chemicals that kill plants. There are many different kinds of herbicides, and each one works in a different way. Some work by killing the leaves of the plant, while others work by killing the roots. Some herbicides are selective, meaning they will only kill certain kinds of plants. Others are non-selective, meaning they will kill any plant they come in contact with.

Video Tutorial: Gordon’s Trimec Lawn Weed Killer

Final thoughts

Thistles can and should be controlled with the help of powerful chemicals. Make sure to read all the recommendations before picking the herbicide for thistles online. Do not forget to leave your feedback about the use of each product applied.