Canada thistle.

Well, we’re digging ourselves out of a “nearly spring” storm here in Calgary – we received approximately 20 cm (8″) of snow yesterday and flakes are still falling as I write this. Just two days earlier, we were basking under +12°C (53.6°F) sunshine, which is pretty typical of the way the weather goes around here at this time of year. I was delighted to get out on Friday morning and take a walk up on Nose Hill, where I ended up sharing the sunrise with five deer and a grumpy porcupine (you can see one of my photos of him here).

While I was up on the hill, I noticed that the City’s war on Canada thistle (Cirsium arvense) in the park is ongoing. I don’t like the fact that herbicides are sprayed annually to control this nasty invasive, but if something wasn’t done about them, the whole park would be covered in thistles. Pulling them simply isn’t a good solution – and it’s not just because they are thorny!

Canada thistle (winter)

CRAZY FACTS ABOUT CANADA THISTLE:

Canada thistle is not a native of Canada. It actually has its origins in Mediterranean Europe.
Another common name for Canada thistle is creeping thistle…as in, it “creeps you out” with its insane root system. 😉
Each plant can produce up to 5,000 seeds.
Each seed can remain viable in the soil for up to 20 years.
Just 8 to 10 days after flowers emerge, plants can already produce viable seed.
Canada thistle reproduces by seed AND by vegetative cloning – a double whammy.
New plants can form from the tiniest of root segments – just 3-6 mm (1/8 – 1/4″) thick and 8 mm (3/8″) long. This is why pulling and digging don’t do diddly.
The tap root of each plant can reach 6 m (20 feet) underground in a single growing season. Isn’t that incredible?¹

I am sooooo glad I don’t have to battle Canada thistle in my flowerbeds! I have a severe problem with quackgrass (aka couchgrass, Elymus repens), however, which I have struggled with for over a decade. While I have made significant inroads, I cannot ever let my guard down….

What are your worst plant enemies?

¹http://www.agriculture.gov.sk.ca/canada_thistle_control

Posted by:

Sheryl @ Flowery Prose

Sheryl Normandeau is a writer and gardening enthusiast living in Calgary, Alberta, Canada, in the foothills of the spectacular Rocky Mountains.

36 responses to “Canada thistle.”

gardeninacity

March 4, 2013

We used to have a plot at a community garden, or allotment as they say in the UK. The worst sin you could commit was to allow canada thistle to get a foothold in your plot. If this happened, the plot was taken out of use for a couple of years and covered with thick black plastic to solarize the soil. Good to know that Canada thistle is not actually a North American native.

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  I wonder what the group leaders of the community garden I belong to would do if they found Canada thistle growing in one of the plots – it hasn’t happened so far, fortunately. We do have a “weed patrol” and they check the plots regularly for nasties… that’s comforting!
  
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Deb

March 4, 2013

Worst plant enemies….dandelions and anything that blows in from the neighbor next door…..I’ve had to go to raised beds that are 3ft high to control their lack of yard maintenance. I am hoping a big fence in the near future may help.

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Oh, isn’t that so frustrating? It’s difficult enough to keep the garden weed-free, but when your neighbours “contribute” as well, that’s just really annoying. Hopefully the fence does the trick!
  
  I agree, dandelions are really troublesome – while they’re not quite as prevalent as the quackgrass in my garden, it seems I’m still always digging them out. And I can never seem to get the entire root…. 🙂
  
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Bella Remy Photography

March 4, 2013

Great capture!

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Thanks so much!
  
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Pat

March 4, 2013

Interesting post. I tried to get rid of lily of the valley in a very dry corner where nothing else would grow. I all but sifted the soil to get all the roots out. About 5 years later they started coming back. In those 5 years, not even weeds grew in this area. 🙂 It wasn’t a double whammy because they didn’t have the seeds – but I understand the root problem.

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Lily-of-the-valley can be such a nuisance (even though it is a really pretty plant!). That is really interesting about the weeds not growing in the same site for five years – I know lily-of-the-valley is poisonous to humans and animals, but apparently it’s allelopathic, too. I’m sorry to hear that it came back.
  
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  1. Pat
    
    March 6, 2013
    
    Not for long. 🙂 I kept after it – and then we moved. 🙂
    
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2. Sandra Pullman
  
  March 10, 2013
  
  Hi Pat
  In Australia, some gardeners would die for a patch of Lily of the Valley. I didn’t know it had weed potential as it is really hard and an expensive plant to get going here. I always thought it needed a damp spot.
  
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Holleygarden

March 4, 2013

20 ft deep root! And to think I always thought Bermuda grass with its ability to come up even under 6 ft of dirt was the worst! Makes me (almost) happy to have to battle Bermuda grass instead of this thistle!

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Oh, I’ve heard that Bermuda grass is really difficult to deal with! What is the best way to rid of it? Do you just keep digging away at it?
  
  Reply
Born To Organize

March 4, 2013

It makes a beautiful photo, though!

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Thanks – I do think they are pretty plants!
  
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  1. Born To Organize
    
    March 5, 2013
    
    🙂
    
    Reply
jmeyersforeman

March 4, 2013

chickweed in the flowerbed, seems impossible to get rid of!

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Chickweed is definitely really annoying! Apparently you can eat it, though, which may or may not be a silver lining! I’ve never tasted it, so I don’t know if it’s a good thing or not.
  
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rainyleaf

March 4, 2013

Horsetail! It’s been around forever and really knows how to survive!

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Yes, it has quite the history, doesn’t it? 🙂 I’ve never seen it trying to invade gardens here, but I’ve seen a lot of it while I’ve been out hiking in the mountains west of the city.
  
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Boomdeeadda

March 4, 2013

I had a neighbour who let his grown as tall as me. I’d go over and tear them out and burn them in our fire pit. Very invasive. It was almost a full time job. Sorry you got all that snow, saw it on the news and thought of you.

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Eesh, who needs enemies when you have neighbours that let their thistles grow unchecked?
  
  Yes, that storm was a doozy, we’re still digging out. But the sun was out today and it was actually pretty nice. The surprising thing was how much snow fell in such a short amount of time. At least it happened on a Sunday and not a weekday morning – a few less traffic accidents that way. I’m glad you were lucky to escape it!
  
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  1. Boomdeeadda
    
    March 5, 2013
    
    Somehow we also missed a Calgary Snow Storm last night….I’m probably jinxing it, but we’ve been very lucky. You’ve got such a sunny outlook, I love that. Yes Monday morning snowstorm would’ve been so much worse.
    
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Cathy

March 5, 2013

6 metres is pretty scary! I have the occasional thistle in my garden and they are very tough, but my worst weed is ground elder (Aegopodium podagraria). Like thistles, it has roots that spread along and down up to 30 feet! Digging and chopping roots only stimulates each tiny piece of remaining root to produce a shoot, so it gets worse, not better! 😉

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  Oh yes, that stuff is pure evil! I actually think the variegated types are rather pretty, but once it gets going, it’s nearly impossible to stop. People here are always planting it underneath trees and then wondering why it gets into the lawn and eventually starts eating the house…. 😉
  
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derek

March 5, 2013

I battled the thistles for 2.5 years at my last house. We didn’t use herbicides, I just went out and pulled them by hand. If you go out after it rains when the ground is still wet, you can get them out root & all. It’s a ton of work but if you keep on it, it can be done. I think the key is to catch them when they are still small and haven’t grown large taproots.

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1. Sheryl @ Flowery Prose
  
  March 5, 2013
  
  It’s definitely better to try to pull them instead of using chemicals – you’re right, get ’em while they’re small! 🙂
  
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Donna@Gardens Eye View

March 7, 2013

I battle teasel and thistle in my meadow…yuck

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1. Sheryl @ Flowery Prose
  
  March 8, 2013
  
  Ugh, that’s a wicked combination, indeed!
  
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angiesgardendiaries

March 10, 2013

I’ve a couple of garden enemies – Dandelion, Lily of the Valley and Kerria japonica – both Lily of the Valley and Kerria come in from next door – under fences it’s an ongoing battle.
i dread when she shows me her latest purchases – there are a few she purchased last year which I know will become a problem for me sooner or later!

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1. Sheryl @ Flowery Prose
  
  March 11, 2013
  
  Oh – that’s really too bad! 😦 I did some reading up on Kerria, and it sounds like a definite challenge to combat that root system.
  
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jeaninerenzoni

March 10, 2013

Garden…lawn enemy – Creeping Charlie…in the lawn, in the flower beds and it smells bad as you pull it. I think it came in with purchased perennials. And we do fight Canadian thistles in our pastures, pull, cut and burn – don’t like herbicides.

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1. Sheryl @ Flowery Prose
  
  March 11, 2013
  
  Going the no-chemical route to fight thistles is definitely the best option, if you can! 🙂 And I’m so glad I’ve never had a problem with creeping Charlie (yet) – it’s absolutely horrible. I feel for you!
  
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Sandra Pullman

March 10, 2013

In Australia, Victoria, a plant called Patterson Curse is a huge problem in Victoria but in South Australia, is a savoir for the bee industry. I have even seen it in the Melbourne in the last ten years. Usually is a country paddock problem.

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1. Sheryl @ Flowery Prose
  
  March 11, 2013
  
  I did some more reading about Paterson’s Curse – it’s a pretty plant, and it’s wonderful that it is a good early-season source of pollen for bees, but it’s really harmful for grazing livestock, isn’t it? Nasty! http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/profiles/patersons-curse
  
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Jo Ann

March 17, 2013

We have some Canada thistle here in Virginia. but it’s not a problem, at least on our farm, but we have plenty of our very own Virginia Thistle that comes up everywhere in poor soil. I enjoyed your blog and am now a follower!

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1. Sheryl @ Flowery Prose
  
  March 18, 2013
  
  Thank you very much for the follow, that’s wonderful! I found a good link that has some information about Virginia thistle http://www.ncwildflower.org/index.php/plants/details/cirsium-virginianum/, as I wasn’t familiar with it. Thistles are definitely adaptable plants! Thanks so much for your comment!
  
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