Wall to wall Canadian Thistle - help!

[chickenannie]

HELP! - I have a wall-to-wall thistle patch where the garden used to be. Last year, I must have pulled out by hand literally half a million thistle plants until I finally gave up in August because it was too overwhelming to do by hand.

I have to garden organically (without any chemicals) and I saw the suggestion to use carpet remnants for 2-3 years, but I'd like to be gardening there this year if I can.

The thistles are already growing 2-3 inches high and there's barely the first sign of Spring here.

Is there a cover crop that would outcompete the thistles? Clover? Rye grass?

Does anyone know if tilling helps or makes it worse?

Does mowing it repeatedly when it's young make any difference?

 

[patandchickens]

Nothing will outcompete canada thistle.

DO NOT TILL -- repeat DO NOT. The problem will get worse, and yes, that *is* possible

Repeated mowing will kill it off more slowly than smothering with carpet, i.e. you will not be gardening there any year real soon.

Sorry, but unfortunately there is no neat and fast solution.

If you really want to garden there this year, my suggestion would be to keep it mowed close for now, wait til you have a warm week forecast, then Roundup the bed (follow directions, more is not better, wear gloves and if you spray also wear a mask and beware killing plants downwind). After a few days or week, rake off the dying stuff. Wait a week or two more til it starts growing back, then Roundup again. You may need to do that one more time. THEN you can plant your garden. But after all this, you will almost certainly still have thistles in your bed, which you will have to pull by hand RELIGIOUSLY WITHOUT FAIL every week or two until about November. If you get behind and they grow upwards, they're strengthening their roots and you are losing ground in the battle. For heaven's sake don't let anything flower.

If you don't want to use Roundup or other glyphosate (and personally, having read up on studies of its actual toxicity and actual persistance in the environment as opposed to the best-case-scenario stuff promulgated by its manufacturers, I don't use it), you can try pickling (not regular) vinegar or agricultural acetic-acid formulations. They do have some effect. Not as good as Roundup. You'd use the process described in the previous paragraph but it will take more repetitions and/or more hand-weeding.

Personally I'd go with the carpet

And btw, to anyone else who's reading this who might someday be tempted to think 'oh, I am too busy and it is too hot and so forth, I shall just let those thistles grow a while longer, they're not so bad and the flowers are kinda pretty after all," ....LET THIS BE A LESSON

Good luck,

Pat, been there, done that, still battling thistles in some areas

 

[chickenannie]

Patandchickens,
I was considering tilling as a helpful measure, so I'm glad to hear that's not the way to go. In fact, I think the problem got much worse 2 years ago when a farmer tilled it for me -- I think it cut up the thistle roots and threw them everywhere.

I am heavily involved in organic farming, so using roundup or chemicals is out for me. After pulling garbage bag full after garbage bag full of thistles out last year, I decided that my heavy hay mulch technique (8-12 inches) was actually GROWING thistles because they had no other competition. the mulch was smothering everything else, but the thistles didn't mind it at all, and i think the lack of competition made it much worse.

I just could not possibly keep up with the thistles by hand -- my plot is 50 x 70 feet, so I may try the carpets. What about newspaper, or cardboard with a heavy mulch on top? Do you think they would work? That way I could allow a 6 inch gap for vegetable planting AND smother the thistles everywhere else.

 

[MeanQueenNadine]

OK Pat I will defer to you on this........ but why not till & then solarize?

 

[patandchickens]

What about newspaper, or cardboard with a heavy mulch on top? Do you think they would work? That way I could allow a 6 inch gap for vegetable planting AND smother the thistles everywhere else.

A significant thickness of newspaper, or heavy cardboard, might well work if you mulched it real well. My only concern would be whether it would last the couple of years you ought to have it down -- my experience is that towards the end of the season it starts getting kinda composted and develops plants poking up thru it. You could always replace it if that happened. If you are going to try to plant thru holes/rows, it might be worth going thru the soil in those areas with a fork and carefully hand-picking out as much thistle root as you can? Dunno, never tried that, just a thought.

MeanQueenNadine, I have not tried solarizing for canada thistle because their roots can go so deep that I have no reason to believe ithe heat would get 'em all, and because i have not read any firsthand accounts of people having that work for them (as opposed to you can find some people who glibly say that *ought* to work ). You can try it if you like.

I still sure wouldn't till first, though, because if it doesnt work near-100%, you are going to have a bunch of tiny separate little thistle plants to have to deal with, as opposed to a more limited number of larger root masses.

Or, till and solarize and see what happens, and let us know

Pat

 

[chickenannie]

I think I'll try part in carpet, part in cardboard/newspaper, part I will mow regularly when small, and I'll keep you posted on what happens. Or, perhaps I can find 4' strips of carpet and plant my rows in between. It will be an experimental plot. I was thinking about putting a turkey pen inside too -- they won't eat thistle, but maybe they'll trample it down and smother it with poop).

The extent of my problem is REALLY harsh, so this is going to take a LOT of work this summer. but it sounds like I have little choice.

Please, anyone, feel free to post any other ideas or successes with serious Canada thistle infestations, if any of you have had them.

 

[Nifty]

"Horizontal roots may extend 15 feet or more and vertical roots may grow 6 to 15 feet deep."

Are you kidding me!? Look at the tap root on that bad boy!
http://www.ext.colostate.edu/PUBS/natres/03108.html



That is just scarry!

 

[ams3651]

http://www.inhs.uiuc.edu/chf/outreach/VMG/cthistle.html

CONTROL RECOMMENDATIONS

RECOMMENDED PRACTICES IN NATURAL COMMUNITIES OF HIGH QUALITY
Prescribed fire can be effective in controlling this species and is a preferred treatment. Late spring burns, between May and June, are most detrimental to this noxious weed and should be used when possible. Prescribed burns to control this plant should not be conducted early in the spring, as early spring burns can increase sprouting and reproduction of this species. During the first 3 years of control efforts, burns should be conducted annually.
Management practices that maintain and encourage the development of healthy stands of native species will help prevent establishment of Canada thistle or help shade and weaken plants on sites already infested.
Repeated and frequent pulling or hand-cutting of individual plants will eventually starve underground stems. Cutting or pulling should be at least 3 times each season, in June, August, and September. This treatment is feasible for light and moderate infestations, but may be relatively time consuming in heavy infestations. Spot application of the amine formulation of 2,4-D according to label instructions can control this plant. Individual plants of Canada thistle should be treated with a wick applicator or hand sprayer. The herbicide 2,4-D amine is selective for broadleaf plants. To reduce vapor drift, use an amine formulation of 2,4-D rather than an ester formulation. Precautions should be taken to avoid contacting nontarget plants with the solution. Do not spray so heavily that herbicide drips off the target species. The herbicide should be applied while backing away from the areas to avoid walking through the wet herbicide. By law, herbicides may only be applied as per label instructions and by licensed herbicide applicators or operators when working on public properties.


My grandfather always did burns in controlled areas and it seemed to work well.

 

[chickenannie]

Burning may work in certain areas, but it wouldn't be possible at my place due to the conditions here.

I wanted to report back on my progress with the Canadian thistle that cover nearly every inch of my 1/8-acre garden last year and starting this year... Especially since I garden organically and refuse to use chemical herbicides where I grow my food.

The area where I pulled thousands of thistles for the past 2 years are fairly thistle free.

In the other thistley areas, I dug 6 garden beds in the spring through the thistles (they were only 2-3 inches at the time) and painstakingly went through with my trowel, removing all the thistle roots and shoots I could find (15 garbage bags full!). Those beds still sprout a lot of thistles, but I weed it regularly and it seems fairly under control there.

The rest of the thistles I covered in some areas with plywood which effectively stunted it. I ended up taking the planks away and mowing the thistles down with my lawnmower which I plan to keep doing every 2-3 weeks for the entire summer to deplete the root energy.

However, I just read that Sudan Grass planted in the spring or summer as a cover crop can outcompete thistle. Organic Gardening magazine states that they recovered a thistle bed in just one season. They let the Sudan Grass grow all summer, then let it die in the winter from the cold weather (didn't pull it out) and then in the early spring pushed over and flattened the dead grasses as a kind of mulch and planted spring tomatoes and veggies in between the dead sudan grass. The thistle did not come back. YAhoo! I'm going to try this. I know Sudan Grass loves hot hot dry weather, so it grows well during july/august/september hot months.

Thought I'd share the info in case anyone else felt the despair I did upon seeing my "garden" full of impenetrable thistles this year.

 

[KayRI]

Wow, and I thought bindweed was the worst weed. I wonder if sudan grass would work for that as well? I'm not sure if I would trade my bindweed for thistle, but this afternoon while I was pulling I think I would have. . .