Any landscape with hard surfaces—sidewalks, stone walls, brick borders, paved driveways, etc.—is sure to have at least a few weeds in cracks. Here are some organic solutions to the problem. Some are more permanent than others.
Temporary Solutions to Weeds in Cracks
Here are a few options for killing weeds that should do the trick when weeds are a temporary problem.
Pouring boiling water in cracks will kill weeds if their roots are shallow. After treating, simply pull or scrape the scalded plants out by hand. (You may have to apply the hot water more than once. Weeds are real survivors!)
Although boiling water won't actually kill mature weeds like dandelions, which have deep taproots, it will offer a temporary respite from them.
Flame weeders work similarly to boiling water, killing weed growth above ground.
Flame weeders produce the best results (weed death) when used in dry conditions on small weeds. If used on larger, deeply rooted weeds, the results will be temporary, much like treating the weeds with boiling water.
A high-pressure washer, like the ones people use to clean pavement and siding, is another way to remove shallow weeds effectively from cracks in sidewalks and driveways. Of course, power washing won't work on gravel, and it could blast away hardscaping as well as weeds if used on cracks between small stones or border pavers.
More Permanent Solutions for Killing Weeds
Removing weed roots and fleshy roots (like the bulbils on pink oxalis, a.k.a. pink shamrock) is a more permanent solution than killing weed growth above ground. For prying roots from cracks, weeding knives and hand forks work well.
Pulling weeds with taproots from cracks is often ineffective. More often than not, the root snaps off, only to sprout again. Weeding knives, which often have thin, hooked blades, slip easily into narrow cracks, making it more likely that you'll remove the whole root.
Although they're not as easy to use against weeds in narrow cracks as weeding knives, hand forks have more uses. For instance, small hand forks are must-haves for removing weeds from beds without disturbing other plants in the garden. They're also handy for prying weeds out of bigger spaces, such as the gaps between edging pavers and stones.
Regularly scrubbing hardscaping with a wire brush is an excellent way to prevent weeds in cracks. It will not only remove weed seedlings, but also weed seeds as well as the dirt and organic matter that would otherwise encourage seeds to germinate.
Preventing Weeds in Cracks
Here are a few techniques that will hopefully prevent most weeds from coming back through the cracks.
Placing barriers like landscaping fabric under gravel and pavers is a good way to suppress weeds—but only if the ground is cleared of weeds first. If the barrier is placed over weeds, some of them will simply force their way through the weaving, and they'll be even more difficult to remove.
Mulch and Gravel
A combination of cleared ground, landscaping fabric, and mulch or gravel between rocks, stones, and pavers is an excellent recipe for weed suppression. Gravel works better than mulch, as mulch will break down more quickly, providing a medium in which weed seeds can germinate and grow.
© 2012 Jill Spencer
Jill Spencer (author) from United States on August 21, 2019:
Sounds like a great method to try, Eugene. Thanks for sharing it here. Best, Jill
Eugene Brennan from Ireland on August 21, 2019:
Hi Jill. This is all very interesting! Another technique I find useful for temporarily removing weeds from cracks is to use a string trimmer (AKA weedeater, strimmer, weed whacker). It's best for "straight" cracks such as the division between concrete sections in pavement. When the head of the trimmer is used with the plane of the line in a vertical orientation, the line reaches deep down into the gap, slashing the stem and root.
Jill Spencer (author) from United States on July 03, 2013:
Thanks W1totalk. We've had so much warm rain lately that everything's growing rapidly here--especially the weeds!
W1totalk on July 03, 2013:
These are great solutions for an attack of weeds. Good article.
Jill Spencer (author) from United States on June 02, 2013:
Very true, Barbara! In this article, though, I limited myself to toxin-free methods, so no herbicides of any sort--even organic. To anyone who does use horticultural strength vinegar: be sure to apply it carefully while wearing protection. It'll burn your skin and could damage your eyes if it splashes into them.
Thanks for commenting, Barbara! A good suggestion for people who want to use an organic herbicide.
Barbara Badder from USA on June 01, 2013:
I've got one for you to add - vinegar. It works really well.
Jill Spencer (author) from United States on January 28, 2013:
Hey Derdriu. I don't blame you for leaving those weeds! As long as somebody's enjoying them, maybe they're really not weeds at all. (: Nice to hear from you! Hope you're loving this cold weather. --Jill
Derdriu on January 27, 2013:
Jill, There's grass that keeps trying to move into the front walk between the two yews, and there are assorted weeds that don't want to leave a bit of the walk near the retaining wall. The hot water treatment has worked for me in other situations. But I decided not to follow through in these two locations since the box turtles, green and tree frogs, and spring peepers appear to consider them their playground!
Respectfully, and with many thanks for all the fine explanations and pretty pictures, Derdriu
Jill Spencer (author) from United States on January 21, 2013:
Thanks, Patricia! We're snuggling up here in MD where it's in the 20s. Brrr! And snow is on the way, too. I can't wait for that! Hope you're safe and warm in FLA. Take care, Jill
Jill Spencer (author) from United States on January 21, 2013:
Thanks, Patricia! We're snuggling up here in MD where it's in the 20s. Take care, Jill
Patricia Scott from North Central Florida on January 21, 2013:
Lots of good tips here, Dirt Farmer. Those pesky little weeds are so annoying. I usually dig them out with a tool of some sort but definitely will try some of your other suggestions.
Have a lovely rest of the 21st day of this new year.
Sending Angels to you :) ps
Jill Spencer (author) from United States on January 03, 2013:
Hi aviannovice! Yep, weeds are always a problem. Here, we tend to weed year round! The fun never stops. (:
Deb Hirt from Stillwater, OK on January 02, 2013:
I think we all have had weed problems like this. Thanks for the great advice.
Jill Spencer (author) from United States on January 02, 2013:
Hi Glimmer Twin Fan! The boiling water trick should work well on those nasty weeds--at least temporarily. Btw, I've noticed recently that I'm actually cultivating several plants that have long been considered weeds, like morning glory, yarrow and vinca. Maybe I need to change my attitude toward chickweed. It would make gardening a lot easier! --Jill
Claudia Mitchell on January 02, 2013:
Another great tips hub! We always have this problem on our front walkway. Boiling water is a great suggestion that I will be trying next summer! Thanks!
Jill Spencer (author) from United States on January 01, 2013:
Hi faythef. Pulling weeds can be a pain, but oh the satisfaction when you actually root one out! Nice to hear from you. --Jill
Hey Pearl! Hope you get that weeding knife for your birthday. It sure will make your garden work a lot easier! Take care, Jill
Connie Smith from Southern Tier New York State on January 01, 2013:
Jill, this is good stuff to learn about. I have never used a weed knife, but I know what I will be asking for as a birthday gift! Thanks for this. Voted Up and Useful.
Faythe Payne from USA on December 31, 2012:
Thank you for the tip..I hate try to pull those buggers out of cracks...
Jill Spencer (author) from United States on December 31, 2012:
Thanks for sharing the hub, Carol! And for your kind words. Happy New Year! --Jill
carol stanley from Arizona on December 31, 2012:
As always you have solutions to perplexing problems in the garden and the plant world. Very good.. Voting up and pinning...