Ph

Tree pH Ranges
As with their wild counterparts, bonsai trees have a tolerance of pH within a certain range according to species. If the soil is outside of the bonsai's pH range, the tree may suffer ill health and lack vigour.

pH: Measure of soil acidity. The pH is a measure of the acidity or basicity (alkalinity) of a material when dissolved in water. It is expressed on a scale from 0 to 14. Roughly, pH can be divided into the following ranges: ...

4. Neutral pH. You soil should neither be too acidic or too basic. A pH level of 6.5 to 7.5 is ideal.
Organic and Inorganic Components for your Bonsai Soil Mix ...

- Ensure balanced pH levels and soil health, and correct if ill health and pH imbalance is apparent. This includes testing the water that you give the Bonsai is pH neutral.

by Nina Shishkoff, Ph.D. and Andy Walsh, M.S.
On the whole, bonsai are probably the healthiest trees on Earth.

Pleger, Ph.D. (2000). The Old Copper Complex of the Western Great Lakes. UW-Fox Valley Anthropology. Retrieved on 2007-08-15.
^ O'Brien, W. (1997). Bronze Age Copper Mining in Britain and Ireland. Shire Publications Ltd. ISBN 0747803218.

Thou shalt determine the ph of thine own water and adjust it to slightly acidic.
Thou shalt immediately, or as soon as possible, remove any new plant from its original potting mix and place it in thine own.

Some trees prefer acid soils with a ph below 7, whilst other thrive in alkaline conditions with a ph above 7. If it is known that a tree likes acid soil, peat may be added to the soil mix.

Water with dissolved salts (pH greater than 7.0) causes trouble. Over-watering kills many more bonsai than not watering enough, and the soil mix is very critical to success or failure. A slight drying between waterings is beneficial.

Bonsai need to be regularly repoted as over time Bonsai can become root bound; the soil runs out of nutrients and often imbalances of salt and Ph levels occur.

Has a neutral PH: Ph 6-5-9
Retains the perfect amount of water
Because of it's volcanic origin it contains high amounts of natural minerals
Indicates that watering is required when the colour changes from reddish brown to yellow ...

Nor did I suggest that you add bone meal or any of those other goodies that the garden centers sell. I skipped the part about checking the Ph too. Ph is important, but I've found that good topsoil almost always has a suitable ph.

Planting medium for succulent plants is very similar to bonsai soil: It should be noncompacting, of generally neutral pH, and porous for good drainage and aeration.

Water quality in terms of pH and hardness are not critical to the fig. Tap water that is adequate to grow other houseplants will work well for the Chinese banyan.
Soil ...

The result is a natural non-toxic, highly absorbtive ceramic granule with a generally neutral PH.
It is dimensionally stable and will not degrade like other amending products.

Increased number of branches
Constant soil temperature
Correct PH
ideal conditions for ion exchange
Development of helpful bacteria
Esthetics
Ease of nutrient application
Eliminates root rot
Increased vigor each year ...

Well drained soil high in organic matter. Soil pH between 5.0 and 6.5.The roots are superficial and fine, so drastic root pruning is not recommended, and it is best if only 10% of the roots are removed.

Lime-hating plants such as Enkianthus, Azaleas (Rhododendrons) and Stewartia require regular replacement feeds of specially formulated fertilisers which ensure that their soil ph remains acidic, ...

Ficus retusa likes to be repotted in the hottest part of summer. The tree is not particular in what type of soil it is potted as long as it is a well draining mix. The PH of the mix does not seem to be a major factor here.

Repot every other year in very well drained mix of 50% organics such as screened fir or pine bark and 50% inorganics (pumice, perlite, haydite, etc). Add limestone or dolomite to the soil mix to buffer the pH of the soil mix. Do not use peat moss.

Most bonsai trees need partial shade. They prefer wet soil but will still survive and do well in moist or dry soil. The main goal with bonsai trees is to keep the soil between 3.7 and 7.3 ph levels.

PH balance needs to be 4.5 to 5.5. It is best to use a soil specifically designed for Azaleas. Because of how root mass grows do not use a soil with particles because these can form mats and make water and feeding difficult.

Good choices are Haydite and an organic component (50/50), or akadama and a grit of some sort (60/40). As their natural soil is often little more than limestone and Juniper bark, keep them around neutral to slightly alkaline ph.

(For bonsai, the container soil may have become waterlogged?) Are there any chunks of mortar or lime-rock in the soil that may be elevating the pH level?

SAFETY: Safety goggles and gloves should be worn while handling lime sulfur. Lime sulfur solutions are strongly alkaline (typical commercial concentrates have a pH over 11.5), ...

The soil should essentially be pH neutral (between 6.5 and 7.5).
A good Bonsai soil mixture should be composed of about 75% inert aggregate and 25% organic materials.

I use about 10% fine slag when doing this. Most garden soil is sweet, since the majority of trees like an acid soil (the slag is acid in content) this will change the ph as the slag leeches into the soil.

See also: Bonsai, Plant, Tree, Species, Growing