Healthy Bonsai From The Ground, Up

Generally speaking one should sift soil in order to screen out particles which would otherwise clog the drainage and impede aeration. The size of the tree and pot has some bearing on particle sizes, but again in general all particles that are smaller than one-sixteenth of an inch should be discarded. Of critical importance is the shape of the particles used. Slightly jagged and rough textured particles will aid in drainage and moisture retention - a seeming dichotomy but actually it is simple physics. A jagged particle will have more surface area, thus a greater tensile cohesion with water droplets, which results in a freely draining, moisture rich environment. As well, folklore has it that jagged particles aid in the growth and development of fine feeder type roots. Although this premise has no explained basis in horticultural science, it does seem to be accurate, at least with my experiences.

Organic components:

The organic material you choose to incorporate in your bonsai soil is largely a personal choice. My favorite organic component is rotted oak leaf, also referred to as oak leaf mold. I choose this material for several reasons:

- It is ridiculously cheap and easy to prepare.

- Of the common organic components used in bonsai soil it is by far the slowest to break down, thus a longer lasting component.

- Oak leaf mold acidifies the mixture (@ 4 parts Terragreen, 1 part oak leaf) to about 6.20-6.25. Fairly neutral yet slightly acidic, which is good for most plants. I can further acidify the soil if required by the particular subject easily, using an acidifier like aluminum sulfate, Miracid, or Hollytone fertilizer.

Other good organic soil ingredients I have seen include rotted pine needles, rotted fir bark, eracacious compost, decomposed pine bark, and a myriad of others.

Bear in mind that regardless of the mixture you choose, a drainage layer consisting of much larger particles (such as crushed lava rock) is really necessary for good drainage. This stratification of soil particles helps break the tensile cohesion I mentioned earlier and creates the positive gravity flow for freely draining pots. This admonition is disregarded in the case of mame or super-miniature bonsai.

Crushed lava rock is often seen in gas station landscapes; it's rusty red in color and also is very economical to use. A fifty pound bag costs just a few dollars. Be sure to wash away all the dust clinging to the rock before

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