Mold, a common household problem, grows in damp, dark and humid areas. Mold comes in a wide array of colours, including black, brown, purple and green. Green mould is typically found outside the home on structures, walkways and concrete. Green mould can create stains and discolouration on your concrete, making the area look old and dingy. Fortunately, it's possible to remove green mould with a few simple items.
Rinse the concrete with a water hose to remove any surface debris such as dirt, leaves or moss.
Mix together 2 gallons of water with 1 cup of bleach in a 5-gallon bucket. Add two to three drops of liquid dish soap and mix with a wooden spoon. Alternatively, substitute 1 cup of trisodium phosphate for the bleach.
Scrub the green mould off the concrete, using a brush broom saturated in the mixture. Scrub the concrete thoroughly, including the areas surrounding the green mould. Allow the mixture to sit undisturbed on the concrete for 15 minutes.
Rinse the concrete with the water hose.
Repeat the process as needed.
Wear rubber gloves when working with chemicals to prevent skin irritation. Trisodium phosphate -- also known as TSP -- is a heavy-duty cleaner available at home improvement stores.
Never mix bleach with ammonia or products containing ammonia. The resulting fumes are toxic.