When used in its undiluted form, bleach is effective at killing weeds, claims Reader's Digest. However, using bleach as a weed-killer requires care, because it is also deadly for any other plant it touches, and it can irritate or damage the human body.
Bleach continues killing weeds for some time after its initial application, according to Reader's Digest. This makes bleach a good option for killing weeds growing out of pavement or along borders, but it is a poor choice for flower beds, vegetable patches or other places where beneficial plants are growing.
Sodium hypochlorite, the active ingredient in bleach, causes irritation when exposed to skin, warns the U.S. Environmental Protection Agency. Bleach is damaging to eye tissues, potentially causing blindness after severe exposure. Due to its hazardous nature, caution is necessary when using bleach as a weed-killer.