Remove and Prevent Garden Patio Stains

Concrete patio slabs often suffer from "staining". This is characterised by black or dark grey marks on the surface. These can be exremely difficult and stubborn to remove manually and wire brushing is likely to do more harm than good.

Causes

The most common cause is roof moss coming loose from the tiles and falling onto the patio. The small roots then try to grow on the surface of the patio slab. When the moss is removed a stain remains - this is organic material and is similar to patio lichen.

Pressure washing the surface of the patio is a simple and often very effective option. However it does not prevent the growth of such stains and is generally a messy and often time consuming process.

Moss Killer Chemicals

One little known trick to easily remove the stains is to apply a fungcide (also known as a moss killer chemical) directly to the surface without any wire brushing or pressure washing.

For this method to be effective the following conditions must first be met:

• Chemical must be high strength - not your usual garden centre type
• Rain should not be forecast within the following 48 hours
• Chemical should be applied liberally

The following is also advised:

• Keep pets and children away from the patio for at least 48 hours after application - use a cover over patio if you wish
• Avoid run off into streams/ponds etc as these chemicals are extremely dangerous to aquatic life

Expected Results

Because the black marks on the patio are organic it will take some time before you see the effects but gradually the patio will brighten up and because the chemicals soak into the porous concrete slabs they will offer protection for up to a year - considering re applying each year for continous protection.