A question recently submitted:
The rocks on the lower part of our house are discolored. I am assuming that it is mold as it is along the lower part and where I have done a lot of watering.
How is this best way of cleaning this off?Â We don’t want to use anything that will damage the mortar.
Masonry can discolour for a number of reasons. Most masonry cleaners are acidic in nature and will remove most mildew or algae that grow on rock work. You have to be careful with bleach based products that will hurt your soil and produce some nasty effluent. Look for a environmentally friendly product such asÂ a biodegradable cleaner that will not kill your grass.Â A little elbow grease and a long handled brush should do the trick.
To prevent this from happening in the future, apply an inexpensive masonry sealer to the rockwork and mortar. It will provide an attractive “wet look” if desired and prevent penetration of organic matter that can lead to mildew and algae growth.