AusBonsai

First of all, i understand its quite difficult for someone to say whether one potting mi is better than another due to several factors. That said, what are your thoughts on this mix?

30% organic (sifted potting mix)
30% diatomite
30% scoria
10% coarse sand

ive been doing some reading around for quite some time, and ive decided ill finally try a "proper" mix for my next repot ( at the moment ive just been using some potting mix and some "bonsai gravel" i found at bunnings in about equal parts)

my understanding behind this mix is that the diatomite provides the moisture retention, the scoria and coarse sand provide the 'air pockets' and keep it well draining, and the sifted potting mix is 'padding' and a safety net in case i miss waterings and whatnot (tends to happen more than i like when i get busy with uni)

i intend to use this mix with the plants listed in my sig below

thanks,

Naimul

The ingredients are OK but you haven't mentioned particle size - which is just as important

Bougy Fan wrote:The ingredients are OK but you haven't mentioned particle size - which is just as important

for the Diatomite there seems to be only one store in sydney that sells it, and its sized 2-7mm, which from reading around is roughly the sought after size. The scoria i can only find in bunnings, and it looks like its about 10mm. the coarse sand im not entirely sure about though, i would imagine something much smaller than the other materials but not so small that it starts clogging up

It depends on what you are growing in it. Smaller particle size = more water retention. If you have trees that don't like wet feet then sift the diatomite. Not really sure you need the sand and have a lot of trees growing without anything organic in the mix. Just grab a crap tree you have and stick it in the mix and monitor it. Different things work for different people in different parts of the country.

I use 2-7 mm in Most of my pots and for small shohin or mame, then i sift to below 3 mm and use that.
the mix you propose will be a good start.

Ken

I use a 50/50 5-7mm scoria and normal premium potting mix down in Melbourne for my grow out pots. For larger grow out pots, I use 30/30/30 scoria, mini pine bark (for orchids) and premium potting mix. I found the bark makes it less heavy. I sometimes use a bonsai mix with my scoria but you pay more for the term bonsai and they usually just contain a bit more inorganic.
I found the larger Scoria sold at Bunnings are too big even for normal plant pot and the mix dries too fast and the large scoria sitting on the surface looks a bit out of proportion.

For my bonsai pots, I shift the fine scoria (which is composed of dust - 4mm scoria), collect the 2-3mm and mix that with a premium potting mix at 50/50. I use a bit more scoria if I want faster drainage for larger pots.

I live in Melbourne. Let me know if anyone want to know where I get my fine and 7mm scoria.

thanks for the responses. I think ill try it out on my prunus but with slightly different numbers. I will probably just get a hammer and smash the scoria if it is too big

Yes where do you get your scoria, I would like to know.

Biofusion wrote:Yes where do you get your scoria, I would like to know.

i found bags of scoria being sold at bunnings

Let me know if anyone want to know where I get my fine and 7mm scoria.
royal1688