Weed killers and herbicides are also helpful because they remove unwanted plants that compete for water, sunlight, and nutrients. Manual weeding is effective, but it's not always practical for bigger lawns and gardens. A fast-acting weed killer is often the best solution for a large infestation. Look for specific lawn weed killers, as the best weed killers for lawns can be different than for gardens. With a wide assortment of natural weed killers and pet-safe weed killers, there's a solution for every lawn.