This is sort of a garden tip. When doing your yard, mowing, weeding, etc. you find you have grass/weeds growing in the sidewalk. It is such a pain to crawl along or bend over pulling them up with TOXIC chemicals. Fill a sprayer with vinegar and go at it.
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If you have pesky grass growing up through cracks in your concrete driveway or patio, just douse the grass with straight vinegar. It will kill the grass.