Pumice stones have been successfully used in Bonsai plantation and other plants in Japan for a long period. Use of Pumice stones in potting mix of garden plants is considered as the best choice because it’s fully organic. For organic farming, use of these stones is increasing.
They are also used in water fountains and landscaping. Pumice stones are light weight, hence we can use them for covering soil around plants. By doing so, they do not put load pressure over the soil under them. Your aerated potting mix continues to ensure root aeration.
Moreover, volume of these pumice is more than stones, hence in purchase of less pumice, you can cover more area of soil with pumice cover. On contrary, if you buy stones/pebbles, you need to spend more for buying more weight of stones. However, if we use traditional pebbles /stones over soil of plants, roots aeration is hampered upto some extent due to heavy weight of stones.