SuperFly Bonsai's USA Sourced PumicePumice is commonly used in bonsai as soil for many different types of trees. You will find pumice primarily in bonsai soil mixes as it helps dry out the mix. One of the biggest benefits of pumice is it's ability to retain some moisture while allowing air to the roots. Pumice generally will not break down over time so it can be used over and over again.  This is one of the three primary ingredients in the well known "Boons Mix" (Pumice, Akadama, Lava) Is It Dirt? No. Bonsai trees do not like "dirt" and will in most cases die if left in dirt over long periods of time. This is substrate. What Is In It?Pumice is a type of Volcanic rock.  Ours is mined out of California.  The pumice may contain a small amount of cinder which is a volcanic rock which is formed around pumice. How Do I Use It? Repot your bonsai tree in this soil if your tree likes dry conditions or mix it with other bonsai soil amendments to create your own soil. Be sure your bonsai pot has holes in the bottom covered by bonsai mesh.Each micro climate may require different amounts of water. On very hot/dry days you may need to water two/three times while around freezing you may need to water just once per month. Push your finger 1" into the soil and feel for moisture. If it is dry, it is time to water. 2.5 Qt = @ 12 Cups 1.25Qt = @ 6 Cups