Moss and Algae in the Garden
Moss and algae will grow on most hard surfaces in your garden, usually they will not be a problem and can be a vital part of the gardens ecosystem. They can become a problem when they form on pathways, drives and patios as they can be a slip hazard and look unsightly.
Any hard surface in your garden is susceptible to a moss or algae build up. The chances are higher if the area has more moisture and less sunlight than normal. The moss and algae do not do any physical damage to the surfaces so if they are in an out of the way place or you don’t mind the look of it then there is no need to do anything.
There are a number of ways to tackle the problem. You can try and prevent it in the first place by improving drainage, maybe the buildings guttering needs clearing or a surface drain is blocked. You could also try to increase sunlight to the area by cutting back vegetation.
To remove moss and algae once they are established you can give the area a good sweep with a stiff brush, this would work better for moss than algae. It will be hard work but is the cheapest option.
There are various chemicals on the market such as patio magic, but, I have found that the best is MMC pro. It needs to be diluted 1 part formula to 4 parts water and put in a sprayer. Soak the area and within a few days it will start to brown and eventually disappear. You may need to give it a brush once it has died but it will be easier than when it was alive.
The final option is to pressure wash the area. It is very effective but requires an expensive pressure washer, gets you very messy and can potentially damage the surface that you are cleaning. This is particularly an issue when doing paving stones as the mortar between the slabs will be loosened by the jet washer.