Hi Ken,
Thank you so much for that, please keep us updated, i hope for all of us this stuff works
Since i had run out of the koreshoffs mix and i had nothing left to use, i decided to make my own soil a few weeks ago. I would have really liked to have included fired clay in my mix........
My mix includes:
Coarse Nepean river sand. This sand was bought at a local hardware store, and the "sand" could more accurately be called fine gravel. Once sifted to a minimum 2mm particle size, you are left with roughly 3/4 what you started with. 20 litres cost me $4.
Orchid mix. The orchid mix i chose was by "orchid care services". It came in a a few different bag sizes and i bought the largest which was 50 litres and cost me $24. Its in a long thin bag which is clear with purple and white writing (I bought it from "Hargraves nursery", roughly 10 minutes from Ray Nesci's nursery). If there were any fines in this, they are in my bonsai pots because i thought the amount was insignificant. Most of my trees are in grow pots at the moment, so none of the particles were too large for this purpose although i did pull out a few of the larger chunks for trees in bonsai pots.
Zeolite. I'm sure you know where to get this
I estimate the bag is about 35 litres? for some reason it is given in weight, not volume (I'm assuming that is because it is used mainly for the petrochemical industry and not gardening). This bag cost me $15.
I mixed them in the ratios i have (e.g. i mixed half a bag of each ingredient, then added whatever i felt was more important for the tree.....i.e. my maples will get more organic, my junipers got more zeolite and my melaleucas got a bit more sand).
I'm still in early days of testing and have only done a few repots as of yet. With this mix, i end up with about 100 litres for $43........I'm very happy with any soil that costs less than a dollar a litre........more money to spend on trees, pots, tools, etc.
I will also be interested if there is a local source of pumice, lava or decomposed granite.......
JayC