I have no idea why we call this stuff soil. There is really nothing in it resembling soil at all. Maybe aggregate would be a better term. Course that sounds more like concrete than bonsai soil so soil it is.
I started sifting six akadama size bags of aggregate I bought at Murayama’s last spring. I purchased too late for repotting last year, but plan on using it this year. I have used this in years past, but the nursery quit carrying it for a period and it was not until last spring and a trip to Sacramento for a bonsai exhibit that I came across it again. The dark granules are a little water that seeped into the bucket.
The aggregate is a pumice blend. It is called Mocha Lava and looks rather like haydite in a way but is volcanic rather than heat expanded shale. The particles are a mixture of some hard lava and a brown pumice material that is full of microscopic pores like haydite. Seems to be some really great stuff. I am grading it into only two sizes, the medium screen on my sifter. That screen is 3/16 and what falls thru I will use for the shohin trees and the rest will go into a blend for all the larger trees. The larger particles run up to larger than 1/4 but not more than 3/8. Mostly around 1/4 inch 5/16 size.
Now all I have to do is sift the cali dama, and the akadama and blend it all together and I will be ready for repotting.
This is the Cali dama stash. Getting harder to get but I have the source here in town.
Close up of the Cali dama. This is a crushed hard pan (clay) product that will never break down and can be used over and over again. Just wash it off and replant in it.