Ratio of 1/6" to other Soil Grain Sizes

Does anyone know if there is a recommended ratio of 1/16" soil particles to the other sizes in 1/16 to 1/4 inch soil blends? Should 1/16" be 10%, 25%, 50% or some other percentage of the total soil you use?


I haven’t heard Ryan ever say something about ratios between particle sizes.

I asked that question on the Q&A and the answer I got was along the lines of “whatever is in the source, we don’t recombine”. I have done some testing of all three materials (most data on pumice and lava) and it really depends upon the source of the material. Bulk pumice was about 30% in both of those size ranges with the rest either larger or smaller. When I sift the Akadama I will see about collecting some data. I sift mine and then recombine. I am currently using 25% of the 1-3 mm along with 75% of the 3-6 mm when I want the 1/16" in. However, I tend to use a slightly coarser mix than most folks I know.

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Thanks Marty.

6-7 years ago the soil components our local supplier sold came unsifted and we had to sift them ourselves.

A few years ago he started presifting them before selling them to us. Nowadays we get very little grains under 1/8". Even the imported bagged akadama seems well sifted. I sifted a 10 liter bag of hard akadama several days ago and got less than a cup of 1/16 size grains.

I do have buckets of 1/16" of APL components left over from before our supplier started doing the sifting. I’ll try your ratio on a couple of trees and see how it works.

Thanks again.

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