The basic mixes are:
5:1:1 mix
5 parts pine bark screened from dust to 3/8" (10mm)
1 part sphagnum peat moss
1 part perlite
dolomite lime
Gritty mix
1 part screened Turface MVP or Allsport
1 part poultry grit (crushed granite or quartzite) screened 1/8 - 3/16" (3.2 - 5mm)
1 part pine bark screened 1/8 - 3/8" (3.2-10mm) OR fir bark 1/8 - 1/4" (3.2 - 6.5mm)
I grow hundreds of woody plants and succulents in the gritty mix, and all else in the 5:1:1 mix.
It should be noted that one can have a number of media components which, if mixed correctly can make almost the perfect soil; yet, the same ingredients can be mixed in such a way that the end product is closer to unusable than usable. The problem with most commercially prepared mixes or custom mixes is that they typically contain too much fine material. If one is to take advantage of the several advantages of a well structured medium (fast drainage and added air porosity), it's essential that the medium has a VERY large fraction (about 80%) of coarse ingredients. Whether or not it's mineral or organic doesn't matter. When a medium is structured such that there is enough fine material to fill all the spaces between the coarse ingredients, you're growing in a medium with drainage/aeration properties which are essentially that of the finest materials. If you have a jar of marbles with huge air spaces between the marbles and you add enough peat or coir to fill all the spaces between the marbles, you're growing in a medium with the same properties as the peat/coir.
Al
