I always thought weed whackers were for hard to reach areas that a mower can't get, but now that I think of the name... can a weed whacker be used to kill weeds?

When I say kill I mean get rid of them without using chemicals or such. Is that possible or is the name just an alliterative selling point?

  • I think "whacker" in this case is meant to use the standard definition "Strike forcefully with a sharp blow", rather than the mafia definition "To kill, knock off, rub out, bump off". I'm almost certain it does not apply to the "homeboy" definition "crazy, ridiculous, appalling in nature, unconventional.", although, weeds are whack, yo.
    – Tester101
    Commented Aug 6, 2012 at 19:36

5 Answers 5


The what, why, and when of weed whackery. Published on the WWW, and written, of course, by W, now that he is free from obfuscating in the oval office (another alliterative phrase.)

Seriously, it can't really do much to kill weeds, as a weed whacker can't really get at the roots of a weed, so all it does is to cut a plant back. To the extent that this weakens a weed, it might do something, but usually that will just slow a hardy weed down. It is useful in spots that a mower can't get to easily, or that would quickly erode sharpened blades. So one can use a weed whacker for edging, or on a brick walkway. However, be careful around the base of a tree, as the string can still damage tender bark.


In addition to @woodchips answer: it might work against some annuals - chop the top off and it dies; but it could make some weeds much worse. Eg. a creeping plant would be chopped up into more bits which could re-root giving you a Sorcerer's Apprentice type situation. Or existing seed heads are effectively spread (dandelions, beggar's ticks come to mind).

Also, Murphy and Sod both say that the plants which will be the most likely to be killed by a weed wacker, are exactly the same plants you want to keep!


Weedwhackers can definitely be used to kill weeds, hence the name. Many people including myself use them for that purpose, it's a real quick and dirty way of controlling them, but you have to be pretty good with it.

The simple trauma of the weed being whipped so hard and so much by the string can be enough to kill a weed, or any plant, alone. It's the same way a tree or bush dies from being constantly exposed to heavy winds, it's just too much for it. But the general idea is to cut them down.

You should start by cutting the weed as low as you can. The weedwhacker string often hits the weed so hard it cuts right through it, but if the weed has really thick stems or stalks it may not be able to do it in one go. If it can't, a lot of strings are serrated so as the weed is getting smacked the string drags across the outside of it and starts to cut little grooves into it, until finally that part of the weed bursts open and the string cuts all the way through, bringing the weed down. Another technique is to weedwhack the top of the weed until it's disintegrated and progressively working your way down, that way when you get to the thick part of the stem it will already be weakened and the string should be able to get through it.

The idea is you're taking away the weed's food supply, and if you cut it really short, even if it survives the weedwhacking, it won't have enough food to be able to grow back, and will rot away in the sun over the next few days, the same way your grass would die if you cut it too short. If the weed is by itself or in a group, after you bring the weed down, you can also angle the weedwahcker down towards the little stem that's left and really dig into the weed, further reducing the weed's chances to live, and, if it's a shallow weed, sometimes it's enough to actually dig the weed up. Any remainders of the weed should be weedwhacked too, until there's noting left of the plant, to avoid the possibility of any part of it rerroting.

It's also important to make sure the weedwhacker is hitting the weed as hard as possible without wasting the string. If the weed is getting hit hard enough, the friction can be so great from the whipping action that the string also burns the weed alive as it cuts it. If you've ever edged the yard before with the weedwhacker, you usually see the grass turn brown where it got hit, which is caused by this. Again, even if the weed survives the weedwhacking, anything that was cut away can't be grown back because of the burns, and the weed is forced to start all over, which, provided enough of it was cut away, it won't have enough food left to do.

It's true there are weeds for which the weedwhacker isn't very effective at all on, including those that are very deeply rooted. Also, as already mentioned some weeds' seeds are spread by weedwhacking them, but at least you've killed the majority of them for the itme being. I use it on the weeds around my house, which are nu,numerous and aggressive, and the majority die, and I only have to do really big sessions with it 5 or 6 times out of the year.


You’ve got to think about how plants grow. The Japanese concept as applied to bonsai regarding trees, roots, and pruning is Energy. The roots store enegry in winter to push out new leaves in spring, and the leaves and trunk are what give energy back to the roots. Mysticism? Well, at least that is their observation because they deal wit( things like root binding in pots and wilted leaves if there’s not enough space or too much root pruning.

As for weeds, most weeds grow like grasses anyway. They stick sappers through the soil and pop up another section of it in a different spot. If you can kill a lawn through mistreatment you can kill a weed. For the sake of argument, supposing you chop up half grouper type weed that sends underground shafts everywhere, the weed still exists, but it will see lack of growth and dieback in the cut spot. Like a tree. Its still not dead yet. So keep cutting. As far as weeds in lawns, the entire point of mowing is to kill off weeds from a well flattened grass hedge. The grass would be grown everywhere under the soil, limiting areas weeds can take root. Ever notice how the grouper weeds rarely grow in a lawn? The more often you mow, the less weeds, because we go back to the issue of energy. If you have a new weed from a seed and cut it in half, the weed will die, since it has no reserved energy and isn’t part of a cluster yet.

In my experience, and what weed trimmers do, weed eating causes the plant to be ripped in half, and that causes it to lose moisture and die. Right right now I have large yellow patches in the weed areas, nice big yellow circles surrounded by green weeds of the same type. Her and their in these yellow patches there are perhaps 5-10% coverage of either weeds that didn’t get the cut, were too low to get hit at the time, or are new oath from seed.

Weeding is about destroying the top until nothing comes back up. You should notice the job gets drastically easier after hewing down the massive infestation. After that, the only reason herbicide seems better than mechanical removal is due to poisoning the ground. Not because it’s better than mechanical at killing orig8nal weeds in any way. Continued weed propagation after 3 or so passes in two weeks is the effect of wind drift, birds, and rodents. Weeds are not immortal or magical.

This all applies to hoeing and gardens as well btw.


Weed whackers mechanically cut weeds. You can kill them by yanking them out, spraying a herbicide, and by using a germination preventative such as Preen.

Weed whackers are likely to kill desirable plants. Rampant ones resprout and come roaring back, so it's not a great strategy.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.