I’m currently using a soil composition of 80% Kiryuzuna and 20% pumice for my white pine, it drains rapidly but I’m thinking to change to
- 40% kiryuzuna 2/5 mm.
- 20% akadama 2/5 mm.
- 20% universal potting soil
- 10% zeolite
- 10% volcanic rock 3/5 mm.

Pines need well draining soil, should I remove the potting soil? Feel free to share your thoughts and ideas !!
Thank you
Nick

The best substrate is largelly depending on your climate and care. Hard to give suggestion on a global forum.

General potting soil is generally a poor choice and for pines even more so. Of course, one CAN grow pines in there but you have very little control on the water status.

I once wrote a generic advice regarding substrate. THe substrate mix I use is very similar to what is used in other places around the world, with a focus on it being open, sifted to a more or less homogenous size and water retentive enough to keep roots moist.

Take a look: www.growingbonsai.net/characteristics-of-good-bonsai-substrate/

The exact components do not matter as much as some would like you believe. Certainly not if you are not working on highly refined speciment trees. Only a few, most notable Azalea, species have special requirements.

Great explanation on that link you sent me. Thank you very much
Regards
Nick