Citra-Shield is designed to work with Mother Nature. Citra-Shield will continue working even if you do not get rain for several weeks, even the slightest morning dew will reactive Citra-Shield. Citra-Shield will continue to clean the surface long after application and will continue to do so until stains are completely gone. Citra-Shield will clean for up to one year and in some cases even longer, climate conditions will determine the length of cleaning duration. We recommend an annual application of Citra-Shield to your outdoor surfaces to maintain clean areas. Citra-Shield will work on almost any exterior surface including brick, vinyl siding, stucco, concrete, metal, wood, composite siding and decking. Citra-Shield works well for your sidewalks, driveways, window sills, patio furniture and more! You will want to apply Citra-Shield when the temperature is above freezing, when it isn't windy and when there isn't rain in the daily forecast. The stain removal time is dependent on the amount of rainfall, the severity of the stain how saturated the surface was originally when applying Citra-Shield. Green stains normally are cleaned in 1-3 days while black stains take longer, about 1-8 weeks. Citra-Shield will not remove staining from rust, tar, copper, tree sap, or zinc. Citra-Shield is safe for plants but we recommend to avoid spraying Citra-Shield directly on your plants and also to water them before and after applying Citra-Shield in nearby areas. One Gallon of Citra-Shield will cover approximately 200 square feet, do not apply when windy to maximize coverage area and to avoid overspray. Using a common garden pump sprayer, saturate the exterior surface to be cleaned, sit back and wait while Citra-Shield cleans with Mother Nature. If want to speed up the process or for severe stains you can do a light scrub with a brush like you would use for washing your car on the stains, then rinse the next day with your garden hose.