How to Get Rid of Canada Thistle | Complete Guide

Everybody wants to have a clean garden, but sometimes this is not possible because of the presence of certain weeds growing in the spaces. Weeds can quickly become a problem because most of them are aggressive growers and will fill up your garden in no time. One of such weeds that have been notorious for this is Canada Thistle.

Your garden may have already been attacked or is currently being attacked. Even when none of such has happened, there’s a high chance you’ll see a Canada Thistle invasion if you don’t guard against it.

This lawn weed will make it difficult for your grass to grow and also increase the work you have to do in your garden. Before we start talking about handling this weed, let’s see what Canada thistle is.

What is Canada Thistle?

What is Canada Thistle?

Canada thistle is an aggressive perennial plant known for its vigorous root system. It keeps traveling towards new areas and producing new shoots there. This is how Canada thistle spreads quickly. The weeds’ scientific name is Cirsium Arvense and is also called creeping thistle because of the way its roots appear in different spaces.

How to Identify Canada Thistle?

How to Identify Canada Thistle

Removal of Canada thistle from your lawn is a hard nut to crack, but it comes inherently harder when it is not tackled earlier enough. The only time you can start early is if you know what type of grass it is. Some of these weeds even look like grass and disguise seamlessly until they’ve taken over your area. So, how do you know you’re dealing with Canada thistle in your garden?

The leaves of the Canadian thistle are deeply lobed and green. They come in shapes resembling spears with sharp barbs on the edges. It’ll prick you if you rub against it. If it reaches the flowering stage, you’ll find a purple flower that forms like a pineapple. This purple flower will turn white and fluffy when it starts to seed. Canada thistle has both male and female flowers. 

Canada thistle stem has no spine. Its rhizome grows aggressively under the ground and produces shoots in another area. This is one of the major reasons it is difficult to control this weed because you have to tackle the root as well as the shoot system.

Now that you know how to identify this weed, you can now focus on dealing with it the right way.

When is The Best Time to Get Rid of Canada Thistle?

When is The Best Time to Get Rid of Canada Thistle

Removing Canada thistle from your garden is challenging because of its growth pattern. If you want to increase your odds of successfully getting rid of this weed, there are specific times where you’re most likely to get better results.

These periods are referred to as the best time to undergo Canadian thistle removal in your lawn. During the fall, Canada thistle is preparing for winter and so takes the period to recharge its roots which leaves it vulnerable. Herbicides also reach the root system faster in the fall. All these make the fall the best time to tackle Canada thistle. Bear in mind that you may have to do this across several seasons before you can completely rid your space of this weed.

Another time is late spring, just when the plant is getting ready to bud. Budding requires a lot of energy, so at this point, the plant has very little stored energy left in it and would be susceptible to your removal method. 

How to Get Rid of Canada Thistle?

getting rid of canada thistle
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Canada thistle is a huge problem in gardens because of its growth pattern and aggressiveness. This makes it difficult to control or remove as it spreads quickly through the help of its rhizomes. It can move up to ten feet within a single season. Many gardeners fear it, and rightly so because regular herbicides and weed removal methods that focus on the shoot system rarely work here.
If these don’t work, what does? This is what we’ll discuss in this section to show you ways to effectively remove Canada thistle from your lawn. Canada thistle can grow back if there’s a tiny bit of it left in the ground. This is why a combination of different methods may be needed to rid your space of this aggressive weed. There are several types of weed killers you can use; these include liquid and granular forms.

#1. Salt and Vinegar Combo

Vinegar is a known weed killer and would work here, too, if done right. This time, you want to make it more effective by using table salt alongside it. Salt and vinegar combo is a natural method for people averse to using herbicides and other chemicals on their gardens. It is more eco-friendly and can bring you the desired results, albeit slowly and selectively.

First, pour the vinegar into a spray container without diluting it. Then you need to cut the stem of the thistle and spray the vinegar directly on it, trying as much as possible not to spray it on the ground. You should then sprinkle salt around the base of the plant on the ground. This will cause dehydration and force the plant to take in more vinegar sprayed on it, thus killing it. 

You’ll need to reapply till the thistle is destroyed. The salt and vinegar method is limited as it can only work when you have only a couple of thistle sprouts to fight. It would become almost impossible to achieve when a whole area has been attacked.

#2. Herbicides

By far the most common method of weed removal. Herbicides have evolved a lot with more specific herbicides for weeds. Two potent herbicides you can use to get rid of Canada thistle are Glyphosate 4 or 2 4-D amine. These herbicides can attack the shoot and root system of the thistle within a short time. 

First, calculate the affected area to know how much 2,4-D amine you should use and then mix 2-3 pints per acre for turf applications. The measurement changes slightly when it comes to fallow land, as you may need between 2-4 pints per acre with up to 10 gallons of water. 

You can start the removal process in the fall. Using herbicides can be dicey, as they can harm other plants that touch it. Therefore, it is advisable to use herbicides where there are no useful plants around it, or you can guarantee a clean spray. You can use a paintbrush to apply the herbicide directly to the thistle and avoid touching other useful plants. 

Apply during hot days when the temperature is around 70°F. You should also avoid windy days as the wind can blow some of the herbicide onto other plants around it. Reapply this till the thistle is destroyed.

#3. Using a Pair of Scissors

All you need for this method is a pair of sharp scissors for cutting the thistle and sharp eyes to spot the weed. You need to spot the thistle early when it sprouts, then clip it from the base with your scissors. 

You should avoid pulling it from the ground as it can break the root and create two new plants from there. Continue coming back to clip every new sprout till you’ve exhausted the plant and it dies.

How to Prevent Canada Thistle from Coming Back?

How to Prevent Canada Thistle from Coming Back

If you’ve taken time out to clear Canada thistle from your garden, you’ll understand what a challenging task it was. The last thing you’ll want is to have Canada thistle back in your yard because of negligence. There are  things you can do and should do to make it difficult for Canada thistle to enter your garden. 

1. Water Properly

Water is an essential ingredient needed for plants to grow. But if you do not water your plants properly, you allow weeds like Canada thistle to come in. Watering too much will leave the place soggy and the root of your plants premature. Too little water, on the other hand, will also cause poor growth, including roots and shoots growth. This will leave the plant vulnerable to any attack from weeds growing.

2. Fertilize

The fertilizer provides the necessary nutrients plants need to grow well, and if your plant is well-nourished, there’ll be little room for weed growth. On the off chance, Canada thistle does grow in that space; your healthy plant will fight it off. Simply calculate the fertilizer ratio for your particular lawn before using it to avoid burning the grass.

3. Reduce the Space Between Plants

Leaving too much space between plants in your garden is enough room for Canada thistle to sprout and start its journey to the other parts of your yard. By reducing the space between your plants, you’re leaving very little room for any weed. And you make it easier for your plants to choke the weeds out immediately after they sprout.


Canada thistle is a widely spread perennial weed, and once it takes shape in your garden, it is quite the challenge to remove. If you want to remove this troublesome weed from your garden, you may have to employ more than one method to be free.

About Jennifer Igra

Growing up in Brooklyn, New York City known for it’s green gardens. Jennifer, a 30 year old gardener and green living fanatic started Igra World to share her gardening journey and increase gardening awareness among masses. Follow Igra World to improve your gardening skills.

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