High quality Akadama Bonsai soil. This coarse substrate provides excellent drainage as well as excellent water retention. In addition, it looks great and can boost the overall aesthetic of any Bonsai tree. It can be used alone or mixed with another medium such as Kurodama or ordinary potting soil.. This Ibaraki Akadama is the harder variety which holds its form and structure for longer.. Features. Excellent drainage. Excellent water retention. Adds visual appeal. Can be mixed with other soils or used on its own. Hard variety, lasts longer before needing to be replaced. Small grain size, most suited to Shohin sized bonsais