When you notice weeds poking their heads through your well-manicured lawn and flowerbeds, check your cabinets before rushing to the store to buy herbicides. Many household products such as salt and vinegar effectively kill plants. They can harm plants you want to keep as well as the pesky weeds, so apply them carefully, covering desirable plants with plastic or cardboard to protect them.
It takes a powerful product such as salt to kill plants and keep them from coming back in areas such as driveway cracks. When you add 1 cup of salt -- just regular table salt works fine -- to 2 cups of boiling water and pour it over the weeds, it starts drying out the roots while preventing them from absorbing necessary nutrients. You can also pour the salt directly onto the soil around the plants; it will soak it when it rains. Either method changes the salinity of the soil, which keeps plants from growing back for months or even years. Pouring bleach on the plants has a similar effect, and it restricts additional plant growth in the area as well.
Feel the Burn
Burning the leaves and making them shrivel effectively stops plants from generating nutrients from sunlight through photosynthesis, killing them. Pouring vinegar, which contains acetic acid, over the leaves while the hot sun shines on them basically burns them. For a stronger weed killer, try pickling vinegar, which has a higher concentration of acetic acid than typical white vinegar. Pouring boiling water over the plants also burns and damages the leaves, the same way it can hurt your skin -- wear protective gear such as long sleeves, closed-toe shoes, gloves and safety goggles to prevent injury in case the hot water splashes.
Remove Protective Layers
Causing leaves to lose their protective waxy coatings means the plants become susceptible to dehydration when the sun hits them. Alcohol works well to remove this coating, exposing the fragile leaf interiors. Reader's Digest recommends using vodka, but nearly any type of alcohol should work. Mixing up to 5 tablespoons in a quart of water produces the desired effect; just pour it in a spray bottle and spritz the plant leaves.
Large areas of weeds need some drastic action. Covering the area smothers the plants, which no longer benefit from sunlight and suffer from reduced oxygen intake. Newspaper works well, with the added benefit of adding nutrients to the soil as it decomposes. Lay newspaper about 10 sheets thick over the area and wet it thoroughly so it doesn't blow away. If you're ready to replant in the area, just cover the newspaper with mulch. Materials such as carpet scraps and old shower curtains also work, although they aren't biodegradable, so you must remove them before planting in the area.