Using chemicals to remove moss can stain concrete. Using an alternative solution is necessary to avoid damaging the concrete surface. One such method is to use a bleach and water solution, diluted to at least 3 parts water to one part bleach. This can damage nearby grasses and plants, however. Another alternative to caustic moss killers is to sprinkle inexpensive powdered laundry detergent on the mossy area. This will effectively kill the moss and will not damage or stain the concrete surface. In order to prevent the moss’s return there must be sunlight on the surface. This means removing any limbs, shrubs, or bushes that are creating too much shade in the area.