cjpa wrote: If so, for so many reasons the only choice is: solid organic fertilizer apropriate FOR BONSAI. But, my friend, you are right, others will work.

I'm going to agree with LB that you are over-thinking it. I do use fertilizer 'for bonsai' occasionally (Biogold), but I mostly use fertilizer suitable for the tree, no matter whether it's a bonsai or not.

Dear Auk,
I was trying to say apropriate for bonsai, not made for bonsai.
In my opinion, and hope this turns into a good discussion of different opinions - when I say apropiate for bonsai I mean that genneraly speaking, chemical fertilizers have a higher content of NPK. That might have implications for example in your internode distances, folliage dimension, etc. Usually, using organic fertilizers - for example biogold, those NPK concentrations are lower which will guarantee a healthy tree but will also help in all other matters. (of course, you can say you water agressively and you control it)
I also believe, and hope you understand that this is my point of view and I would very much like to hear yours also, when you say that I'm over-thinking it I don't agree. For example, if I were to ask you what type of substrate do you use, probably you would say something like akadama+kiryuzuna or perlite, crushed bricks, well something like that. I could also say you are overthinking it. You could use plain soil earth, it would work! but for sure you don't use plain eath, because there are so many benefits of using a porous apropriate substate for bonsai. We like to provide the very best option within our knowledge to the trees.
So, then again, I really bealive that using solid organic fetilizer is the best possible option. But I also know, you can use other fertilizers and still have good results, but in my opinion, the best possible option is as I say solid organic fertilizer, like for example KIORYOKU, BIOGOLD, JOY AGRIS, etc... Also, those fertilizers are developed for bonsai, fertilizer is fertilizer, but sure there will be slight differences,,, Honnesty, I personally would prefer to use humus than to use a chemical fertilizer, for example.

Thank you again for sharing with me you opinion, and hope to turn this into a good discussion, I honestly welcome your comments.
Best wishes to you all

cjpa wrote: if I were to ask you what type of substrate do you use, probably you would say something like akadama+kiryuzuna or perlite, crushed bricks, well something like that. I could also say you are overthinking it. You could use plain soil earth, it would work! but for sure you don't use plain eath

Actually, I do use ordinary soil. And Kiryu, Kanuma, Akadama, perlite, and some more. Depends on the plant and its stage of development and the mood I'm in at the time of potting. I see so often advise is being given to beginners, about very specialized soils, techniques, fertilizers and what not.
I don't see the point. For trees that are still in a development phase, I really don't need all that. Just well-draining soil and ordinary fertilizer.

Well, we just have different points of view... Let's move on.
Thank you very much, best wishes.

cjpa wrote: Well, we just have different points of view... Let's move on.

Let's. I would be interested to see your bonsai and what the effects of your soil and fertilization methods are.

I use liquid fertiliser now as all my trees are still in development so I can push them to grow when I want, but I'm pretty sure that when my trees reach a point where I just need to maintain them I will switch to solid , simply because it is easier and less hassle .

Try californian worm fertilizer. Its like steroids for plants.