The best way I know how to kill sidewalk weeds is to spot spray with a nonselective herbicide. It will take a week to shrivel up and die. Eventually it will disintegrate.
Landscapers choose to week wack any dead remains to the ground. Some homeowners use a shovel to scrape out the remains.
The term nonselective herbicide means it kills any plant it touches. Garden centers sell nonselective herbicides under many brand names. The most common brand name is Roundup, whose main ingredient is glyphosphate. This chemical causes weeds to stop producing proteins and they starve to death in 7 to 10 days.
Word of Caution
A nonselective herbicide doesn’t discriminate which plants it kills. So be very careful spraying close to the bordering lawn or desired garden plants. If you are nervous about spraying too close to the lawn or landscaping, make sure you shield what you want to protect. Use a newspaper as a drape.
Do NOT spray on a windy day.
These chemicals are most effective when the temperature is over 70 degrees Farenheit.
Manually Pulling out Weeds
I do NOT recommend using your two hands to pull out weeds. This is too labor intensive. Not to mention, it is difficult to pull out the all the roots. That means the same weed will keep coming back.
Boiling Water Kills Weeds
If you don’t want to spend the money on weed control, boiling water will do the job. It’s as simple as it sounds. Boiling water acts as a nonselective herbicide since it damages any plant it contacts. Use common sense and don’t do this if you fear it might touch the bordering lawn and/or landscaping.
This is method of weed control also won’t harm people, pets, or the environment—as long as you don’t burn yourself in the process.
Never Ending Battle
Expect the need to kill sidewalk weeds more than once. Landscapers spray Roundup several times a year on patios, walkways, sidewalks, gravel driveways, and in plant beds. Nature is persistent. So stock up on weed control.