Removing stains on stones

Image: iStockphoto | 12 May 2008

I have a collection of many beautiful stones, big, about 15 cm x 10cm x 10cm... grey and green. After a few years they developed stains, It looks like a disease, although it's probably not. What can I do? Wash them with soap? Use chlorine?

Sheena Adams, Organic expert

Your stones sound like they are aging naturally with mineral build up and a few natural stains from the outdoors. You may clean them using a dish soap and water with a soft brush, rinsing well. Or leave them to age gracefully. The dish soap will not harm your garden, choose a phosphate-free product.