Hawaiian cinder mixes for foliage plant production are composed of varying ratios of natural occurring volcanic cinder and Canadian or European sphagnum peats.
This produces a superior potting mix, which has attributes of:
1. Water holding - peat & cinder
2. Cation exchange - low cinder, higher for peat
3. Porosity - high cinder moderate coarse peat
4. Shrinkage - cinder doesn't break down; long lasting type of peat.
5. Longevity - cinder never long lasting type of peat.
Two of the most important attributes are longevity and porosity. Many other soil mixes use wood chips and/or wood by-products to create aeration. As time passes on, these materials degrade and create loss of porosity and thus drainage, which eventually causes plant mortality. Also, since porosity does not dissipate in a cinder mix, there is adequate O2 in the soil mix, which eliminates many of the pathogens that cause root rots.
Another attribute of the cinder mix is water is drawn up by capillary action, which makes them compatible with sub irrigation practices. Since there is little, if any, decomposition of organic materials, there is a much lesser change of bothersome soil insects.