When you use a fertiliser that contains a strong amount of iron you risk spreading small amounts of fertiliser onto concrete surfaces. These acid-based stains can be unsightly on a concrete patio or driveway, but in removing the stains you don't want to risk hurting your lawn; a common mistake is using bleach to treat the rust stains, which can damage your lawn.
Remove any fertiliser on the concrete by sweeping it off with a broom. Keep your garden fenced to prevent animals from spreading the fertiliser to your concrete surface.
Determine the type of concrete that has the rust stain. For example, if the rust stain is on your driveway, use a remover specific to the type of cement. Other types of concrete surfaces include granite and marble.
Spray the area of the rust stain using a hose with a high-pressure nozzle. This will help to get rid of any dirt, dust or build-up that is trapped in the concrete where the rust stain is. Allow the area to dry for an hour.
Apply an organic rust remover to the concrete stain. Do not use a rust remover that contains chemicals that could damage your concrete or lawn.
Let the application of rust remover sit for up to an hour or as instructed on the package. Spray the area using your hose again to remove any excess liquid and let the area dry. Repeat the process if portions of the stain remain until it is fully removed.