Good points here from both constantstaticx3 and Gnome.
Keep it as simple as possible IMO [For your own sanity
Disclaimer for the casual reader: All numbers represent starting points NOT the perfect percentages, Tweak to your preferences/requirements.
I do some entirely inorganic trees but a good way to do it for you would be to use about 45% organic for your tropicals. [About a 1:1 mix I/O]
[These %s are far
more than I would use but you have some severe
heat in mid summer to deal with and such a mix will retain moisture longer.]
Temperate species are variable but you could start with about 30% organic. [About 3:1 I/O]
For your conifers about 15% or maybe
20% organic. [Again you have some severe heat...] [About 5:1 I/O]
The mix of grit and Akadama is up to you [One is far cheaper than the other
It will take a bit of experimentation to sort out what is most effective for both your trees and you.