AusBonsai

Just remembered this thread as I was grading and combining another batch of mix today. I had a mixed bag of 'fines' (under 2mm) (mainly from pine bark, diatomite, soft scoria plus other bits a pieces) that, after buying the largest kitchen sieve I could find, I have now created a .5-2mm (basically grit minus the dust) that can be utilised for mame and possibly shohin. It also contains a measure of zeolite.

I'm also wondering if this fine grade mix, or even just a sprinkle of fine grade (.5-2mm) zeolite would help retain more moisture/nutrients/roots at the surface?

Jow did you trial putting a finer grade on top level of your large trees over the last year ?

Hey Ryan,
A couple of experiments I've done lately have shown that any fines will get washed down through the mix to the bottom of the pot. I think this will cause drainage issues as the fines would block up the holes in the mesh.
I have seen sphagnum used on the surface to help retain moisture although I have never tried it personally.
Hope this helps.
Mal.

I like to lay a little layer of sphagnum moss at the top layer to act as breathable blanket for the surface soil. I started doing this after noticing some crispies in amongst the top soil of some tridents I uave fattening. Works a treat.

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golgotha wrote:I like to lay a little layer of sphagnum moss at the top layer to act as breathable blanket for the surface soil. I started doing this after noticing some crispies in amongst the top soil of some tridents I uave fattening. Works a treat.

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pommie_mal wrote:Hey Ryan,
A couple of experiments I've done lately have shown that any fines will get washed down through the mix to the bottom of the pot. I think this will cause drainage issues as the fines would block up the holes in the mesh.
I have seen sphagnum used on the surface to help retain moisture although I have never tried it personally.
Hope this helps.
Mal.

Thanks guys, I've tried this before (spag moss) after seeing some Japanese doing it, and might try chopping finer this time.

pommie_mal wrote:Hey Ryan,
A couple of experiments I've done lately have shown that any fines will get washed down through the mix to the bottom of the pot. I think this will cause drainage issues as the fines would block up the holes in the mesh.
Mal.

Interesting Mal, I haven't had this issue myself on shohin and smaller. I put a thin layer of larger particles on the bottom and then and the mix of fines on top and it all drains fine. The fines do incorporate into the gaps in the drainage layer, but the larger particles still stay at the bottom and do help with drainage.
I evn got lazy on a couple last year and instead of using the mesh over the holes, I used shade cloth instead...still drained fine.
I also used turface as a top cover on some grow pots filled with a mix of larger diatomite particle size, and they stayed on the surface and didn't fall to the bottom of the pots. If any did it wouldn't matter in my mind when using a larger size particle for a drainage layer.
I know some growers say a drainage layer is not needed etc. I use one for the above reasons, not to stop water pooling at the bottom of the pot, as I use a mix of mostly diatomite etc and don't have that issue.
I also notice that in the Japan repotting videos I have seen, they pretty much use a slightly larger particle size at the bottom of their pots.

Just my experience, not disputing your experiments.
Cheers, Dario.

Hey Dario,
It's good to hear other opinions & experiences. Mine were small scale experiments, only 4 pots, so it's definitely not conclusive. They were also larger pots, not shohin, so that may have contributed to the results.
Cheers
Mal.