Thistle be easy, I hope.
August 8, 2009 7:52 AM   Subscribe

How can I kill the thistles in my yard?

These things are persistent, ugly, and painful, and I want them gone. I've tried pulling them up, but I usually only get 10cm or so of the root before it snaps off, and in less than a week I have a brand spanking new plant. I want a more permanent solution.

I have had a plausible solution described to me, but I want some feedback before implementing it: Is it possible to use a Q-tip or some contact applicator to apply roundup or some other herbicide to the plants without affecting the rest of the lawn? If so, how, and which herbicide?

I'm open to other suggestions as well. I don't want a solution that will take massive amounts of money and labour, because my next door neighbour's yard is also infested, so I'll be repeating the process again and again, I'm sure.
posted by ChrisR to Home & Garden (10 answers total) 1 user marked this as a favorite
It's possible to use a Ortho Weed B Gone type product for your species of lawn. I have used the type that connects to the hose and it works well. I think I have tried the Spectacide version as well. I have killed dollar weed and other broad leaf weeds with it without killing my lawn. It can stress it though and there are temperature constraints so read the directions thoroughly. Also, as you know prevention is easier than a cure. Use a spreader with weed inhibitor granules in the Spring and Fall.

Roundup is available in a foam formula. If you want to go that route I would use the foam only on very calm days.

It doesn't sound like you want to continue pulling them but a good goal is to pull 5-10 weeds per day. And use a spade to get down there. Soon you will have made a huge dent.
posted by Fairchild at 8:12 AM on August 8, 2009

It's more of a long-term approach, but you could look at your soil fertility. It sounds like the thistles are growing in a lawn (sod). What shape is the lawn in overall? Usually weeds in a permanent sod are a sign of imbalance, either nutrients (N,P, K) or pH. A cheap soil test would tell you if you need to lime or fertilize. That, combined with pulling (or even regular mowing) would be a lasting solution.

Also, pull them before they go to seed, and if they have seeded, burn them.
posted by werkzeuger at 8:32 AM on August 8, 2009

Weed burners are effective, low effort means of weed control. A few minutes a week knocking back the visible portions of the plants eventually clears them from your lawn, if you're not getting significant windblown seed from neighboring property; the key is keeping eradication pressure on them to prevent seeding. In late winter, you can put down a broadband pre-emergent product, to help control them systemically.
posted by paulsc at 8:36 AM on August 8, 2009 [1 favorite]

You can do what you're talking about, but a more effective method might be to put on a plastic or nitrile glove, then a cotton glove over that, and use your hand to wick the plant with RoundUp, which should do a complete job on the thistles. You can also find generic RoundUp- look for the active ingredient Glyphosate. It's the same stuff, but probably cheaper.

Weed-Be-Gone would work, as well, but it's primary active ingredient is 2,4-D , which can't be applied when daytime temperatures are over 85 degrees or so (I'm writing from memory, so I might be a little off).

Some pre-emergent would be a good idea this fall, as well. And once your turf is dormant, spray round-up on the whole yard. As far as I'm concerned, anything that's green in January is a weed (in the yard, that is).
posted by Shohn at 8:49 AM on August 8, 2009

I would recommend against using RoundUp on the grass, dormant or not. Apparently it can work if fully dormant but I don't think most grasses achieve that.
posted by caddis at 9:34 AM on August 8, 2009

soak the area with water for as long as you can with damaging any nearby structures (like flooding a basement). I did this once, I let a hose run and soaked the area for 12 hours. then I put heavy rubber gloves on and easily pulled each plant out of the mud. I did this when they were flowering, before they went to seed. the thistles never came back

do your neighbors lawn also. or pay a kid to do it

this is so much more sane than poisoning your own environment when your life does not depend on it. not like you are starving and you will loose your crops if you don't use herbicide. that would make more sense
posted by cda at 9:43 AM on August 8, 2009 [1 favorite]

You're basically looking for a broad-leaf weed-killer. RoundUp will kill everything, but broad-leaf killers are more narrowly targeted and thus won't kill your grass. You'll still have to go around and pull 'em once they're dead, but they won't come back after this. Weed-B-Gone will work, but if you go to the gardening section of your local hardware store someone will be able to point you in the right direction.

cda's option is potentially more environmentally friendly, but less likely to be permanently effective. You really have to do it right for that to work long term, and the potential for missing something is high. Also, depending on how much you pay for water, this may or may not actually be cheaper than just getting the herbicide.
posted by valkyryn at 9:58 AM on August 8, 2009

When I moved to my current home almost 20 years ago, there were thistles taller than I am in the garden spaces. I realize I'm not especially tall, but c'mon, those thistles were big!

I don't recall any herbicides -- not even RoundUp -- having much of an effect on the thistles. In fact, I believe that thistles were curiously absent from their list of weeds they can eliminate.

cda's suggestion of using water to soften the dirt before pulling the thistles sounds like a good one. I can report, happily, that after pulling the thistles a few times, they didn't return. We have considerable undeveloped land around us and airborne thistle seeds are everywhere, I'm sure.

We occasionally get a few in the garden, but they are easily dispatched. Fortunately, they don't have an elaborate or particularly deep root structure. Be sure to wear heavy leather gloves when pulling them, though. Thistles are not something to be messed around with while wearing anything else on your hands.
posted by DrGail at 10:17 AM on August 8, 2009 [1 favorite]

Growing up on a farm in a state where it's illegal to have thistles on your property, my family and I found that the best solution to eliminate thistles was to take a hoe and dig them up. That way the entire plant was eliminated, root system and all, which seemed to be effective. On 160 acres, however, there were way too many thistles to dig up individually, so we often used a spray similar to Roundup.

If you want to avoid making small holes in your yard, it's probably best to go with Roundup or some other chemical. Watering the ground before you pull up the thistle sounds like a good suggestion and, like DrGail said, if you want to hand pull the thistles, wear thick gloves.
posted by Coyote at the Dog Show at 1:57 PM on August 8, 2009

One day my grandparents took my cousin & I out to the pasture in their pickup truck. We sat on the tailgate, and hopped off every time we spotted a thistle stalk, then mowed it off low with a hoe.

The plant spends so much energy building those flower stalks that it often can't recover. Thistles were gone from their pastures for years, they told me.

Now, if those were biennial thistles, there'd be no way they'd survive, but the next year's crop (the even-year biennials, if you will) would be unaffected. Thus, they must have been perennial thistles.

Moral of the story: if you have biennial thistles, this method will take at least two years to fully work.
posted by IAmBroom at 9:48 PM on August 11, 2009

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