In this section we go underground. It is most helpful to not only know but to understand the complex situation being played out in the ‘soil’.

The original Japanese bonsai mixes were based on the composition of the earth. The rock & lava in breaking down created the next grade, which then eroded & so eventually including organic matter thus becoming humus becoming fine topsoil. This is how our earth was created; bonsai mix is another matter.

Next tip the living soil...

All the Structural & Horticultural aspects that have been applied to bonsai can, in the end be to no avail unless you have some knowledge of the activity being played - out beneath the surface. By going underground we can learn the importance of a series of effects that will determine & explain the successes & the failures we have. More importantly perhaps, is it - to know and understand what and why it failed.

We constantly hear the term LIVING SOIL. What does it mean? Soil (potting mix) should be a hive of activity. Without it the soil is useless – DEAD. The organisms & bacteria have wants & needs like the plants. Firstly, before attending to your plant, the scene has to be set for the underground activity to commence. Secondly, the host has to be prepared to house the bacteria.

We are talking here about the good (aerobic) bacteria, which develop & multiply and are hosted in humus, which is (the final stage of organic matter when its source becomes unrecognisable). So, what then is the function of aerobic bacteria? Well its purpose is to prepare pre-food (fertiliser) to the next stage for plant uptake. This is by ingesting & emitting an acidic substance to the fertiliser that conditions it for the next stage. Without the good bacteria, fertiliser is useless.

It becomes positively dangerous when bad bacteria (anaerobic) is present in a mixture where airless & waterlogged conditions exist. Under these conditions the good bacteria cannot survive. Conversely, bad bacteria will not survive where oxygen abounds.

Next, the story continues with fungus...

Fertiliser is simply raw material at the initial stage that must pass through several stages of adaptation before it reaches a condition where it is able to pass through an osmosis membrane in order to be pumped up the tree. The bacterial modification is the first stage. The next conversion is by an extremely important fungus called Mycorrhiza, which has a mutually beneficial association with all plants.

One is aware of its presence on some plants by the white cotton wool appearance surrounding the rootball. Its association with all plants is crucial for long range health & wellbeing. Caring for both the obvious (fluffy & white) & the not so obvious (internal) mycorrhizae require the same treatment as as we provide for our Bonsai. There is much more to explain at this stage which is continued below.

The beneficial cycle of plants is determined by both the underground and crown, each one is dependant on the other. Each unit benefits the whole.

The initial journey began with the raw food (fertiliser). The function of beneficial bacteria is to generate aerobic conditions for the next step. Nitrogen plays an important phase in all aspects of plant development. Although part of the greater cycle as a whole, it has its own cycle of - absorption, nitrogenous host (humus) as well as its release back into the atmosphere, where the process begins once again. At this point the required conditions have been prepared for Mycorrhiza...

The next stage in the development for the ‘perfect’ bonsai mixture is, by popular opinion to be mycorrhiza. In the past, the purpose for the fungal development, especially noticeable around the roots of pine trees, was believed to improve the growth of a young pine. Failure for active development of this symbiotic fungus to appear gave rise to the belief that it was an incompatible potting mix. This is far from the truth as observed by us with our 1951 pine - bonsai Collection.

The Collection is potted into a very porous P.M. described as the ‘Rolls Royce’ mix, so imagine our surprise about 20 years age to notice the lack of ‘cotton wool’ conditions usually associated with pine trees. Using, at that time, such a radical mix, observing the vibrancy of the foliage made it hard for us to understand the lack of mycorrhiza around the rootball.

The answer will continue...

This tip provides an explanation for the lack of symbiotic wool-like fungus development around the roots of a repotted pine bonsai about 20 yrs. ago . It seems the porosity of our ‘soil mix ’ was so beneficial for plants, mycorrhiza at that time was not required.

Leaving subsequent rootpruning for 18 years in order to observe, learn & understand the underground activities; surprisingly, the bonsai continued to elongate & flourish. It was only as roots began to fill the pore-spaces & slowing the water flow-through from 5 sec. to about 9 to 10 sec. that mycorrhiza began to appear, & by the time of cutting- back the roots they were covered with fungi.

The more porous (there is a limit) the mix: our ratio is - to one unit by volume of crushed stone 2- 5mm. add up to half the volume of a humus other than peat, and adding an appropriate fertilizer, meant there was no need for additional assistance for plant growth. Such a potting mix had more than enough aeration surrounding the roots, especially for nighttime ‘food’ manufacturing, making it unnecessary to provide more air.

It seems that the purpose for mycorrhiza, is to create aeration for the roots where the density of the earth or potting mix prohibits access of oxygen to surround the roots. Only when this situation occurs will mycorrhiza enable the manufacturing of the elements absorbed during the day to proceed. This is a major requirement for the health of all plants.