Bonsai soil is one of those subjects where everyone seems to have a different opinion- so I guess I get to share mine. I hope you find this helpful. Why care about bonsai soil? Like really, isn't it basically the same as any houseplant soil? Bonsai soil is different than regular houseplant soil and it needs to be.
I Want my Bonsai to get BIGGER!Unless you work to prevent that, as long as you can keep it alive, your bonsai will inevitably get bigger. But left in a bonsai pot and trimmed so that it doesn't look like my "lock-down" hair, it will take a long, long time.