AusBonsai

I think orchiata bark comes from NZ.
If they are selling it for orchids it will be good for bonsai too.
Pine bark may draw down a little N so you should include some slow release N in the mix to compensate. The bark does not seem to take much N then it releases almost as much as it takes so doesn't seem to cause long term problems.
My mix has around 70% pine bark and works well for me here.
20% bark in your mix should not cause any problems.

Formulating your own mix can be fraught with problems - things you have not even thought about - AFP, WHC, pH CEC and nutrients.Professionally formulated mixes take all the guesswork out because they know what they are doing.
Changing all your trees to an unknown mix could have consequences. I would certainly do a trial run for a year to assess the new mix before committing all my trees to it.

Changing all your trees to an unknown mix could have consequences. I would certainly do a trial run for a year to assess the new mix before committing all my trees to it.

This is vital. I sell "magic" akadama as well as UXP, scoria, pumice and kanuma. I always emphasise to anyone using inorganics for the first time to trial on a crap tree. Never put your best JBP straight into a new mix. Your micro climate or watering habits may not suit the mix and it may need modification. Just because it works for Boon in California doesn't mean it works for Mike in Melbourne. Having said that I have not looked back since I switched to inorganics and the fine root development alone makes it worthwhile.

FreddieV wrote: ↑July 28th, 2020, 8:27 pm Orchiata is available here, but the make I have is similar to that..so the man from the orchid society say.
It's not composted and that's my concern....orchiata as far as I know aren't composted either.
The orchid people say they wet it, then add dolomite (1cup per 40l bag) to it. It stabIlizes it, and remove tannins....apparently. Helps the new roots cling to the bark. Let it soak for two weeks before use.
That's what i'm doing...figuring, it adds calcium/magnesium so it can't do much harm...or can it?
Bottom line is i'm contemplating whether to add it or not...

Freddie, Orchiata already has dolomite added to it. Enough to bring the pH to about 6.5. No need to add more. Use it straight out of the bag.

Thanks Mike. Yeah as I said above...this is not Orchiata. It's similar in quality though. Much cheaper. Seems the only difference is...it hasn't been 'dolomited' yet

Anyone experienced using "quarter minus"? i saw it on the jobsite today, seems a good aggregate. it's the blue metal plumbers use as bedding for drain pines.

I used plumber's grit for a while. It is a good size but does vary a bit depending on the source. Up here most comes a pit on from alluvial river gravel so a lot of the stone is rounded which is not really the best for potting mix. It is also very, very hard so cutting with the root shears at repotting is more difficult and quickly takes the edge of the tools.