For myself if I was planting trees shrubs to pots that I intended to hold in pots for a longish time I might want a drier looser soil like:
1 part soil conditioner (pine bark) sifted
1 part sifted granite grit (also sold as chicken scratch)
I use a one gallon scoop for my 'parts'
Other flavorings like sulfur, oyster-shell, compost, osmocoat pellets get used by the spoonful to cupfull.
What ever will not pass through a 1/2 inch hardware cloth is too large. Discard the gravel, chunks.
What ever will pass through a 1/16 inch window screen is too small, discard that too.
This is pretty much what I use for bonsai soil too.
