Soil for Maples in Southern climate

Hi Jonas,
What type of soil do you use for your early and mid-developent Acers and Tridents? Being in Southern Texas makes soil for Maples very important and challenging. I have talked with several other Bonsai friends in Dallas, Austin and San Antonio. There is a split between APL and APL with small pine bark chips. Any recommendations?

Hi Sally - I’d aim for a straight APL mix. If the trees need moisture then I’d up the percent of akadama. I try to avoid organics like bark in the mix as it works well for a while and then breaks down which can cause problems.

I have also avoided organic content in my Bonsai mix for developing maples. The typical reason for addition of pine bark is to increase moisture retention and or increase PH. Both can be accomplished with changing the percentage of Akadama as Jonas has suggested!
I also suspect the divided opinion is partly affected by watering routines and excessive periods of heat. This can also be addressed with depth of substrate and substrate covers such as sphagnum moss.
Root ball characteristics for maples are key to development and having similar particle size and shape to promote root style decided should also be considered. I find this easier to manage with inorganic components. Bark is difficult to size and control particle shape.
That being said, with adapting proper care routines either can be successful!

I live in Charlotte, NC where pine bark is cheap and Akadama is expensive. As I evolved into Bonsai from other tree and shrub gardening, I have been growing field maples from seed and cuttings for many years. I start with seeds and seedlings in with best practice nursery mixes which has a high PB content (seedlings in PB fines)t, as the trees get bigger and depending on the tree type I increase the particle size. PB fines for small trees and seedlings 1/4" to 3/4 " for pre Bonsai. When the tree is moved into the refinement stage I go to traditional Akadama: Pumice: Lava Rock 2:1;! for maples (1:1:1 for junipers and pines). I am of the opinion that a carbon source in the soil (pine bark, compost etc.) speeds up the growth of the root system and with the APL mix there is no Carbon in the mix so the plants’ only source of carbon is CO2 from the air which is assimilated through photosynthesis and travels from the leaves to the roots where it is used judiciously. This results in finer roots which results in smaller internodes. I have 25 years from seed Tridents and JAMs moved from the field to 16" to 24" plastic pots in APL mix. Thank goodness I could not understand why everyone I spoke to who apprenticed in Japan said Akadama was magic, so I tried it for myself and it is. So I am trying to understand why (I bought 100 bags as a test sample).
I still grow all my nursery stock in best practice nursery mixes and now use more and larger drainage material. I also use larger diameter and shallower pots.
Best of luck,

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