In the standard mix (which I think nobody uses) there are equal amounts of lava rock and pumice. What do they do differently?

I know one is white and the other is red or black, so there is a visual difference.What would be the difference in tree growth between all pumice and all lava?

Hi,
You say "In the standard mix (which I think nobody uses)".
1, why doesn't anybody use it.
2, would you use a soil mix made up at a bonsai nursery like this
Bonsai soil
The trees I have are all broadleaf and larch
Thanks
Graham

The standard specified here on the Empire is 1/3, 1/3, 1/3 pumice, lava, akadamia for coniferous and 1/4, 1/4, 1/2 for deciduous. Quite a few people refuse to use akadama, and quite a few people mix some amount of organics of different kinds, often ground pine bark or something similar. I put a lot of organics is because usually I can't water in the middle of the day and I need water retention in the summer months.

The question would be why 1/4, 1/4, 1/2 instead of half lava half akadama, or half lava rock, half akadama.

Interesting question. BEsides lava being heavier, stronger an absorbing more water I see no reason why to use it over pumice. Maybe it is in there to give the substrate some weight? I know that is why I sorted it out of my mix very fast. I do not like heavy substrate in 60cm pots..

Thank you for your replies/advice this gives me something to work on to mix my own soil.

Potbound wrote: Thank you for your replies/advice this gives me something to work on to mix my own soil.

Some more substrate thoughts, hope it helps you: www.growingbonsai.net/characteristics-of-good-bonsai-substrate/
Substrate is wildly debated. Some approach it as a science (Without actually being scientists); Some consider specific recipes gospel and others look for alternative routes for all sorts of reasons. Just realize.. The perfect mixture is the one that works for you, under the conditions in your garden and under your care regime. If you have problems, you have 3 options: change location, change care or change substrate mixture.