I whitewashed our garden walls a few times and whilst some areas of the wall were fine, I couldn't stop some areas from flaking (despite changing the formula to include boiled linseed oil which is supposed to help prevent flaking). After three failed attempts, I scoured the surface to remove loose substrate and painted over it with white masonry paint. Now the major issue is the green which has appeared. It looks like something of the plant kingdom. Should I just apply moss killer to the wall? Can I add salt to the masonry paint to stop this from reoccuring?
