Ways To Get Rid Of Canadian Thistles
This article was co-authored by Ben Barkan and by wikiHow staff writer, Hannah Madden. Ben Barkan is a Garden and Landscape Designer and the Owner and Founder of HomeHarvest LLC, an edible landscapes and construction business based in Boston, Massachusetts. Ben has over 12 years of experience working with organic gardening and specializes in designing and building beautiful landscapes with custom construction and creative plant integration. He is a Certified Permaculture Designer, is licensed Construction Supervisor in Massachusetts, and is a Licensed Home Improvement Contractor. He holds an associates degree in Sustainable Agriculture from the University of Massachusetts Amherst. This article has been viewed 7,316 times.
Canadian thistle is notorious for its spiky leaves, purple flowers, and rapid growth rate. The fluffy seeds that grow in the spring are light enough to catch on the wind, so the thistle can spread rapidly, taking over entire habitats in the blink of an eye. If you have Canadian thistle in your area, you may need to spend multiple seasons trying different management techniques to get rid of it completely. Prevention and early treatment are key, so dont wait!
What Is A Thistle:
Thistle is one of the most stubborn herbaceous weeds of the daisy family that spreads using lateral roots and airborne seeds. It is harmful enough for your lawn also, it is classified as a noxious weed in many countries and states.
You are already familiar with the term weeds. Weeds are unwanted or undesired plants that grow in your lawn. You have to get rid of these weeds if you desire a kid-friendly yard, as they can spread quickly in your grassland areas and borders. But it is not an easy task for you to remove it permanently to get a kid-friendly lawn.
When Does Canada Thistle Grow
Because its a perennial plant, Canada thistle never dies. It comes back every spring and, if left unchecked, can become a real nuisance.
Once firmly anchored in the ground, it can spread quickly via a robust root system. Vertical tap roots can penetrate up to six feet into the soil searching for water and nutrients. Sideways-growing rhizomes, 12 to 18 inches underground, can grow up to 12 feet per year, allowing Canada thistle to aggressively spread and propagate. That makes killing it difficult.
And as if that wasnt enough, each of those beautiful purple flowers will distribute up to 5,000 seeds, effortlessly spread over your landscape by the wind. Seeds can stay viable in the soil for up to 20 years before germinating when conditions are right.
Canada thistle can be found in all 12 Canadian provinces and territories and 43 of 50 U.S. states, avoiding the South and Southeast for the most part. Canada thistle is considered a noxious weed in most states, meaning its control is required by law.
Recommended Reading: When Should I Fertilize My Lawn After Seeding
How To Prevent Thistle
Thistle spreads quickly once it turns into a seed, so if you are removing thistles by hand make sure you do so long before the flower has changed. Thistle seed can also bury itself deeply, so aerating and seeding as much as possible will prevent thistle from receiving enough nutrients to grow.
Thistle that is removed before it has an opportunity to spread may not sprout new broadleaf weeds. But once it has started spreading you are going to need some type of application to remove it from your lawn. Contact Green Lawn Fertilizing today to learn more about our green lawn and broadleaf weed removal services.
What About Canada Thistle In My Lawn
With its aggressive ability to spread, theres a good chance this dastardly weed could eventually make its way into your lawn. To control Canada thistle, use Roundup® For Lawns1 Ready-To-Use to spot treat plants as they appear. To prevent future Canada thistle invasions, routinely fertilize your lawn to keep it so thick and lush that theres simply no room for weeds.
You May Like: Are Battery Powered Lawn Mowers Worth It
When Does Thistle Appear
Thistle weeds appear in spring, show their flower buds in late May or early June, and by the end of June, theyre in full flower. Shortly after this, and definitely by mid-July, thistle flowers have produced seeds, which are dispersed by wind, wildlife, and ignorant landscapers . In September, after the dog days of summer have passed, new shoots emerge from the roots, which survive until cold weather sets in, usually in November. This new growth replenishes underground store reserves to give the plant lots of power to overtake more of your garden the following spring.
Use A Weedkiller Concentrate To Treat The Whole Lawn
Its rare that your lawn will be taken over by just one type of weed. Usually, if theres a lot of one type of weed, there will be plenty of others too.
Spot spraying in a situation like this is futile. Treating the whole lawn with a selective weedkiller concentrate is the only option.
Products like Weedol Lawn Weedkiller Concentrate are designed to be diluted in water and applied using either a knapsack sprayer or watering can.
When using a weedkiller concentrate, be sure to read the instructions and mix the concentrate accurately.
If you make it too weak, youll not kill the weeds. Make it too strong and you could kill the grass as well as the weeds.
Don’t Miss: What Does Trugreen Do To Your Lawn
Aerating Your Lawn Can Work Wonders
Walking on your lawn is bad for grass and good for weeds. It compacts the soil and prevents air, water, and nutrients from reaching into the ground. If the conditions in the soil are poor, grass cannot grow, but thistles still can.
Invest in an aerator even a cheap, manual one and use it occasionally. It works best if you take the time to cover your whole lawn and not merely where you have a problem with weeds. Again, anything that is good for grass growth is bad for weeds.
Plant Extra Grass To Crowd Out Thistles
Thistles grow on parts of your lawn where the grass isnt growing properly. The more you water, fertilize, aerate, and in other ways, take care of your lawn, the fewer problems you will have with thistles. If there is strong, healthy grass all over your lawn, thistles wont have any room to grow anywhere.
You May Like: Is It Better To Water Lawn In Morning Or Evening
What Is Yellow Nutsedge
Nutsedge is a perennial weed that comes in different colors, with yellow nutsedge being the most common in the USA.
Classed as a noxious weed, its important to treat and remove this plant immediately if you see it growing in your garden, otherwise, it can do serious damage to surrounding wildlife and plant life.
Managing Thistle Growing Between Landscape Plants
If you are trying to manage Canadian Thistles in landscape areas that have desirable plants, you will need to use a selective herbicide. There are some products that work great on thistles but wont harm the majority of woody ornamental plants. This means it is possible to kill thistles in a bed of junipers or other groundcover if they are emerging, which is a task that hand-pulling would never accomplish effectively. Consult with a landscaping company that offers vegetation management services who will know what plants are able to handle these herbicides without any injury to desirable species.
No matter what your situation with thistles is, you will need to treat these areas many times throughout the growing season. Some areas will require 4-7 applications of herbicides throughout the year and even may warrant a few hand-pulling projects after weeds are wilted down and brown.
If you have problems with thistles in your landscape and would like to know the options for their control, please contact us.
Receive special promos and offers
Also Check: When To Fertilize Lawn In Arkansas
Shade Is By Far The Best Way To Control Thistle
When thistle pops up in your shade garden, it has little energy to pop up again if you nip it in the bud. When it appears early in the season near your tomatoes, dont fret too much. By mid-season, the tomatoes will shade it out and the thistle will give up, assuming youve been knocking it back while young.
If you give thistle a wide-open, sunny expense of clay soil, all hell breaks loose it will fill up that space almost overnight. So fill in every possible space in your garden with plants you love, to shade-out and out-compete the thistle seed and young shoots. If you have any open space, pop an annual or a ground cover in there, or use a nice vegetative mulch to fill it in and smother the thistle. If you dont allow thistle the opportunity to start, youll rarely see it.
Keep The Flower Heads Of Thistle And Hence The Seeds In Check
When flowers appear, yank them off immediately and toss them in the compost bin . By keeping the plant from flowering and seeding, youll save yourself a lot of work next year. Much to every gardeners chagrin, thistle seeds have been known to remain viable in the soil for up to twenty years, so get those flowers when they first appear, if not the whole plant.
You May Like: What Can I Use On My Lawn To Kill Fleas
Is Canada Thistle Safe
Canada thistle is not a safety concern. However, its no fun to step on with bare feet.
If you have kids who like to roll around in the grass, youll hear about it if they find a thistle! Pets and wildlife shy away from thistle plants because of their prickly natural defense mechanism.
If one of those thorny barbs ends up in your hand or foot, simply remove it with tweezers, like you would a sliver. They contain no harmful toxins.
Now Trending
Use A Spot Spray Weedkiller For Lawns
If the weed persists after digging them out, or the idea of digging weeds up sounds like too much hard work, you can give them a blast with a spot spray weed killer for lawns, such as Scotts Weedol Lawn Weedkiller Spot Spray or Resolva Spot Spray Weedkiller for Lawns.
However, if youve got a bigger problem and its taken over your lawn along with other types of weeds like Daisies or Clover, for example, youll need to treat the whole lawn.
Recommended Reading: How To Control Weeds In Lawn Naturally
How To Get Rid Of Canada Thistle
When starting a Canada thistle control program, it is best to first understand what makes Canada thistle such a difficult weed to control. Canada thistle grows on an extensive root system that can go quite deep into the ground, and the plant can grow back from even a small piece of root. Due to this, there is no one and done method of Canada thistle eradication. Whether you are controlling Canada thistle with chemicals or organically, you will need to do so repeatedly.
The first step towards getting rid of Canada thistle is making your yard and garden less friendly to it. While Canada thistle will grow anywhere, it grows best in soil with low fertility and open areas. Improving your soils fertility will weaken the Canada thistle and help desired plants grow better and, therefore, make them better able to compete with the Canada thistle. We recommend having your soil tested at your local extension service.
How To Kill Thistle Weeds With Roundup
Another great way to get rid of thistle is by using a store-bought weed killer like Roundup. Using chemical herbicides that require no mixing or preparation ahead of time, these commercial products eliminate common weeds like dandelions and thistle without a problem.
The activating ingredient in Roundup is glyphosate, which penetrates down into the earth to attack the plant roots.When using this thistle spray, coat every part of the thistle with the herbicide until it soaks deep into the soil.
If there are plants nearby that you dont want to be affected by the Roundup spray, then shield them using a piece of cardboard. Allow for at least three days to pass before you notice results in thistle plants.
If theyve started to wilt and brown, they are ready to be pulled from the ground. Prevent thistle from growing back near other plants by placing wood chips or mulch around them.
Don’t Miss: How Do I Kill White Clover In My Lawn
Thistle Is A Pioneer Plant
Thistle is whats called a pioneer plant, like dandelion: Give them bare earth, and they will fill it in promptly. This pioneering actually provides a great service in the wild, by protecting the soil from erosion until larger plants can take over, and by feeding pollinators like bees and butterflies where little else may exist. And by virtue of thistles deep tap roots and extensive root systems, many air pockets and water pathways are created in the hard soil, encouraging the soil ecosystem along. So dont hate on thistle too much its only doing its job.
More Information About How To Kill Thistles Without Chemicals
Thistles have a very invasive root system, which is one reason why they are so difficult to eliminate. The ideal time of year to treat Thistles is late Fall, when they are pulling all their energy into their roots to prepare for Winter. Taking advantage of this seasonal function will help facilitate the absorption of the Organic Weed Control products you use.
Good Luck! Have any other suggestions? Feel free to share!
Recommended Reading: What Is The Best Weed Killer For Your Lawn
When Is The Best Time To Get Rid Of It
To fully eliminateCanada thistle, you must injure and deplete its root system. This is likely a process that will take repeated steps over multiple seasons. Unlike other plants, eliminating thistle is not done in one day.
Fall is the best time to get rid of thistle. During the fall, the thistle is preparing for winter by recharging its root system. This allows herbicides to travel directly to the root system, maximizing injury to the plant.
Late spring is the second most important time to get rid of the thistle. When the plant is getting ready to bud, it requires a lot of energy. This means it will be at a seasonal low of stored energy, making it more susceptible to herbicides.
How Do I Identify My Canada Thistle
Canada thistle is a perennial weed with yellow flowers. It is considered a noxious weed because it crowds out native plants and is considered to be a weed by many farmers, gardeners, and landscapers across Canada.
It can be identified by its flat leaves that are up to 10 centimeters wide. The leaves do not have teeth at the edges and grow from an underground stem that can be up to 1 meter long. The plant also has small white flowers that bloom in mid-to late summer on short stalks near the leaves of the plant.
Canada thistle has a strong, pungent odor when crushed or pulled apart.
amzn_assoc_placement = adunit0
Don’t Miss: How Often Should I Mow My Lawn
How To Prevent Thistles From Growing In Your Lawn
Good lawn care practices will prevent Thistles and other weeds from growing back.
Like I always say, weeds are a symptom of other problems as a result of poor lawn care practices.
If you follow these lawn care treatments, your lawn will be so thick and lush, there will be no room for weeds like Thistle to grow.
Chemical Canada Thistle Control
Canada thistle can be killed with weed killers. The best time to apply these is on sunny days when the temperatures are between 65 and 85 degrees F. .
Since many weed killers are non-selective, they will kill anything they touch, so it is best not to use these on windy days. If you need to treat Canada thistle where it is close to wanted plants, you might be better off using a paintbrush to paint the weed killer on the Canada thistle.
Check back weekly and reapply the weed killer as soon as you see the Canada thistle reappear.
Don’t Miss: Does Lowes Take Trade In Lawn Mowers
Canada Thistlethe Tough Weed That Just Wont Quit
Controlling Canada Thistle can be difficult, a stubborn root system means that without continued management, the weed will return.
Canada Thistle is a creeping-root perennial weed and can be identified by spear-like leaves with sharp barbs that reproduces from vegetative buds in its root system. Once it flowers, the flower is purple and produced in clusters. Once the flower turns to white, the plant is ready to seed. Canada Thistle has gained a reputation of being hard to remove, and rightly so, the roots extend deep into the ground and even the smallest left over root can regrow. According to Colorado State University Extension the horizontal roots may extend 15-feet or more and vertical roots may grow 6- or 15-feet deep.
Many different types of areas on lawns or landscapes are highly susceptible to Canada Thistle. It can flourish in a wide range of moisture conditions and typically emerges first in the spring time, but it also grows in moderate summer temperatures with rainfall. Canada Thistle has a tendency to take over areas where it goes untreated. Multiple weeds can grow from just one section of root.
Prevention and Treatment
There are three different styles of herbicides that can be considered for removal and treatment of Canada Thistle.
