While most people look forward to the spring and summer months, they also bring an unwelcome guest to your yard: thistles. It seems as if seeds have a way of finding your lawn or garden annually, and although they’re an eyesore, they pose a more serious problem.

Getting pricked by thistles is painful, and some can be allergic to them. Pets always seem to find their way into thistle brush as well and then you’re tasked with cleaning them up. Plus, thistles can outcompete your lawn and compromise its vibrant, lush appearance.

Don’t worry, we’re going to show you how to get rid of thistles for good. From tips on how to kill thistles using a thistle weed killer to advice on how to remove thistles from lawn naturally without chemical intervention, you’ll be equipped to control the outbreak by the time you finish reading.

But it starts with adding the best weed killer for thistles to your arsenal, and you needn’t look further than our strong weed killer here at Jennychem. Weedex Super is a powerful acetic acid weed killer which means you don’t have to worry about toxicity, either! Learn more below.

What are Thistles and Why Are They a Problem in Your Yard?

Before we get into how to kill thistles you should know what they are and why you need to act fast when you spot them. This aggressive, fast-spreading weed can quickly dominate a lawn or garden if given the opportunity to do so.

You probably know thistles when you see them - they’re characterised by spiky leaves and vibrant purple or pink flowers. But they aren’t just painful to step on or bump into. They have deep taproots that make them difficult to remove completely. 

When they infiltrate your lawn or garden they pose an even bigger problem. They compete aggressively with desirable plants for nutrients, sunlight, and water. Before you know it, you have a lawn full of thistles and dead grass.

Thistles are notorious for spreading rapidly because of how abundantly they produce seeds. But did you know there are actually a few different types of thistles? 

• Creeping Thistle (Cirsium arvense): A deep-rooted perennial that spreads aggressively via underground rhizomes, making it one of the hardest to eliminate.
• Spear Thistle (Cirsium vulgare): A biennial thistle with sharp spines and tall, flowering stalks that can reach over a metre in height.
• Marsh Thistle (Cirsium palustre): Often found in damp soil, this species can spread quickly in poorly drained areas.
• Musk Thistle (Carduus nutans): Produces large, nodding flowers and can quickly dominate pastures or open spaces.

Any of these are worth taking the time to remove from your garden or lawn. But that’s where the challenge of learning how to get rid of thistles lies: even microscopic root fragments left behind can quickly blossom into a new plant.

Manually removing thistles sounds like a nightmare not just because they have such extensive root systems to pull out, but because they’re so sharp. You need some pretty thick gardening gloves to protect against painful pokes. This begs the question: will weed killer kill thistles?  

Will Weed Killer Kill Thistle? Choosing the Best Thistle Weed Killer

Weed killers, commonly known as herbicides, use a variety of compounds to disrupt essential plant processes, ultimately leading to the plant’s death. They can more or less be broken down into two distinct categories:

• Selective Herbicides: These target specific types of plants, such as broadleaf weeds like thistles, while leaving grass and other desirable vegetation unharmed. If you want to learn how to get rid of thistles in lawn, this is what you’d use.
• Non-Selective Herbicides: These kill any plant they come into contact with, so they’re great at clearing out stubborn overgrown areas but risky for use in lawns.

So will weed killer kill thistle? While there are plenty of thistle weed killer options you can choose from, you need to set your expectations. Not all weed killers for thistles will work well.

Why Thistles Are Hard to Kill With Typical Weed Killers

You can’t use the same bramble weed killer or dandelion killer for lawns on thistles because they have really unique survival mechanisms that make them more resilient to weed killer. These include:

• Deep, Hardy Root System: Thistles often regrow from root fragments left behind after cutting or pulling. Surface treatments are typically ineffective.
• Waxy, Spiny Leaves: Their protective foliage resists absorption and prevents the active compounds from fully penetrating the plant and getting down to the root system.
• Fast Seed Production: Even if a thistle is weakened, it can still produce thousands of seeds, leading to a recurring infestation. You might kill the first plant, but you’ll then be left to deal with its offspring.

Although most generic weed killers aren’t strong enough to control thistles, there are certain systemic, selective herbicides you can try. 

What to Look for in a Thistle Weed Killer

So what kills thistles? There are a few active ingredients you should make sure you bring to the fight. 2,4-D, dicamba, and MCPA can successfully control broadleaf weeds like thistles without damaging grass.

Remember, though, the herbicide has to travel from the leaves to the roots to prevent regrowth. This means you need a systemic herbicide, not a contact kill. 

While some UK gardeners try to avoid leaving behind residual compounds in the soil, this can actually be a good thing for controlling thistles which are notorious for popping back up shortly after being killed. 

If these types of solutions fall short and you’re still left dealing with a frustrating thistle infestation, you may have no choice but to rely on a non-selective herbicide that will kill anything in its path. 

Decimating all vegetation and starting fresh with new lawn seed is a last resort, and that’s where our weed killer shines. It’s the strongest acetic acid-based herbicide in the UK!

The Best Weed Killer for Thistles is a Click Away at Jennychem!

Weedex Super has helped tens of thousands of gardeners manage a variety of tough weeds, ranging from ivy to nettles and even thistles. 

Because it’s powered by acetic acid you won’t need to worry about weed killer and dogs, cats, or other wildlife. It’s non-toxic once it dries on the surface of a plant. Make no mistake, though - despite being gentler on the environment it’s aggressive on undesired vegetation.

Now, how long does it take for weed killer to work? You’ll see visible effects within hours as the thistles wilt and die from intense desiccation. It’s a fast-acting way to control thistles.

 Weedex Super is perfect for areas where you want to eliminate everything - whether you need the best driveway weed killer or are trying to get a grip on your garden’s thistle outbreak.

Just keep in mind Weedex is non-selective - it’s going to kill any plant it comes in contact with. Sometimes, though, it’s far less work to eradicate an entire lawn and start fresh with new seed next season. That being said, let’s get into how to get rid of thistles using herbicide below.

How to Kill Thistles With Herbicide 

Once you’ve chosen your thistle weed killer it’s time to get to work! Learning how to kill thistles with herbicide starts with an understanding that timing is everything. 

Best Time of Year to Apply Herbicide for Maximum Effectiveness

Our advice on when to spray weed killer on thistles is in the spring before flowering. Thistles are still in their early growth stage at this point so they’re not as strong and resilient to chemical interaction. 

If you missed the boat here, though, your next best bet is autumn before dormancy. Thistles store their energy in their roots for winter survival as summer winds down. Applying it at this point all but guarantees it gets absorbed and carried deep into the plant to prevent regrowth next season.

Just avoid wasting your time with herbicide application in mid-summer as thistles are in full bloom and most resilient. Seeds will continue to spread at this point anyway, so you’d be fighting an uphill battle. The same can be said of winter dormancy since the plant isn’t absorbing chemicals at this point. 

Step-by-Step Guide to Using Herbicides on Thistles

At any time of year, wait for a calm, dry day with no rain in the forecast for a few days. Then, follow our step-by-step guide below on how to kill thistles:

1. Prepare the Area: Cut down tall thistles to a manageable height but leave enough foliage for absorption.
2. Apply Herbicide Correctly: Use a sprayer for broad applications or a brush for targeted spot treatments. Thoroughly coat the leaves for even coverage, but avoid letting the product runoff into surrounding grass (if using a non-selective herbicide).
3. Monitor and Reapply if Necessary: Some deep-rooted thistles might survive the first application. So if thistles show signs of regrowth, repeat treatment after a few weeks.
4. Dispose of Dead Plants Carefully: Wait for the thistles to dry out completely, then remove them to prevent reseeding. Do not compost treated thistles, as seeds or chemical residue may persist.

There you have it, how to kill thistles with a thistle weed killer. But what if your outbreak is resilient to herbicides, or you simply don’t want to use chemicals? We’ve got more tips on how to get rid of thistles below. 

How to Get Rid of Thistles Without Chemical Intervention

There are so many ways to naturally control thistles - be it rock salt for weeds, a homemade weed killer recipe UK gardeners have relied on for centuries, boiling water, and more. We’ve compiled a list of methods that have proven effective against thistles in particular.

Manual Thistle Removal Techniques

When it comes to how to kill weeds permanently and naturally, you simply cannot beat manual removal. Sure, it’s a bit more labour than you may have hoped for, but it works. 

The best time to remove thistles by hand is after rainfall when the soil is soft, otherwise, you can wet the area with sprinklers or a garden hose to make the job easier. Use a weed puller or garden fork to dig deep and extract the entire root system, as any fragments will regrow.

Keep in mind that manual thistle removal works best on young plants that haven’t flowered yet. Be sure to wear protective gloves so you don’t poke yourself on those sharp spines this plant is notorious for.

Does Cutting Thistles Kill Them?

Simply cutting thistles at the surface will not kill them, as the root system will just prop up a new plant in its place. That being said, repeatedly mowing or trimming thistles can weaken them over time, especially if you do so before they flower and seed.

Try cutting down thistles every few weeks and combine this with other control methods, as the best defense against this weed is a multi-faceted one.

Does Vinegar Kill Thistles?

Definitely! After all, the main compound in vinegar is acetic acid, which you know now is a powerful thistle weed killer. It acts as a desiccant to dry out thistle leaves upon contact, essentially dehydrating them to death.

However, household vinegar (5% acetic acid) is too weak to kill the roots. Stronger horticultural vinegar (20-30% acetic acid) is what you need for best results. That’s why we once again encourage you to pick up the best weed killer for thistles today at Jennychem.

Remember, though - acetic acid is non-selective as an herbicide so it could damage your lawn or any surrounding vegetation that it comes in contact with. 

Using Boiling Water for Thistle Removal

There’s another way you can kill thistles without chemicals or manual labour - using boiling water. Pouring it over the plant damages its cells and kills leaves instantly. 

But like cutting thistles down, it doesn’t really have any impact on the roots. Regrowth is likely unless you dig up the soil around the plant and pour the water onto the top of the root mass.

Even still, you should combine boiling water treatment with manual removal, applying it immediately after cutting thistles down to help kill the roots.

How Rock Salt Can Help Control Thistles

If spraying chemicals sounds offputting, maybe applying rock salt will align more with your gardening principles. It’s a great way to dehydrate plant cells and kill thistles naturally. Sprinkle it at the base of the thistles and water it in so it penetrates the soil and works down to the roots. 

One caveat to keep in mind is that salt can also make the soil uninhabitable for other plants, so use it only in driveways, gravel paths, or non-lawn areas where regrowth won’t be an issue.

Smothering Thistles With Mulch or Tarps

Thistles need a few things to thrive: water, sunlight, and oxygen. You can take all of these away and slowly but surely squeeze the life out of the weeds using mulch or tarps.

Cut the thistles down as low as you can and then cover the area with a thick layer of mulch, cardboard, or tarps to block sunlight. The plant won’t be able to photosynthesise, which will weaken it and eventually cause it to die.

It could take several months, though, so be aware that this is a long-term play. Speaking of which…

Soil Health Adjustments to Prevent Thistles Naturally

There are a few adjustments you can make to your soil care regimen that will not only kill thistles but prevent them from returning. These include:

• Aerate compacted soil: Thistles thrive in compacted, low-quality soil. Regular aeration encourages grass growth and empowers your lawn to outcompete thistles.
• Improve nitrogen levels: Fertilising your lawn makes it harder for thistles to establish themselves.
• Adjust pH levels: Thistles prefer low-pH (acidic) soil. Applying lime can help raise pH, making conditions unfavourable for thistles but perfect for healthy grass - win-win!

Thistles are just one of many garden foes you may encounter here in the UK. Our blog has more tips on how to get rid of ground elder naturally, what kills nettles permanently, and the best weedkiller for ivy. Learn more about protecting your property as we wrap things up below.

Closing Thoughts on How to Remove Thistles From Lawn

We hope this guide on how to get rid of thistles has left you feeling clear and confident in your next steps. As resilient and frustrating as this weed can be, it’s not impervious to certain control methods. 

While manual removal, soil improvements, and natural methods can weaken their grip, deep-rooted infestations call for a more aggressive approach. You may have no choice but to apply a non-selective thistle weed killer like Weedex Super.

If that’s the case, we’re here to set you up for success. Our products paired with these tips on how to kill thistles will help you regain control of your lawn or garden in no time. Take the next step today!