If you have some stubborn weeds or grass peeking out between patio stones or the cracks in your sidewalk, don't resort to toxic methods quite yet. Instead, try boiling a kettle of water. Take your kettle out to the offending weeds, and holding it close to the top of the weeds, slowly pour the water out onto them. If stubborn plants with a long tap root are the source of the problem, you can cut off the top of the plant, dig a small hole to the side of it, and then direct the water towards its taproot. If the weeds reappear, simply boil another kettle of water and use the same technique. It doesn't get much cheaper, or nontoxic, than that!