90% Pumice / 10% Vermiculite?

[Punky]

I am having a hard time sourcing akadama or any of it’s widely accepted alternatives other than vermiculite and composted bark. I have a few things in 100% pumice, but it’s a little too dry for my watering habits. I almost love pure pumice but I just want to add a small bit of water retention and cation exchange. I plan to experiment the with composted bark on some low value plants, but I also want to give vermiculite a try.

Up for discussion in this thread:
1. Ratio of pumice to vermiculite you might recommend.
2. Thing I should look for on this trial run.

Please do not discuss alternatives because I am trying this no matter what. I just want tips on how to increase the odds of success and issues to keep in mind during my observations.

I see vermiculite criticized heavily, but usually by people who say they used 100% vermiculite and it held too much water. I do not propose using a lot of vermiculite, just a pinch in the mix to increase water retention and add some cation exchange capacity to my lovely pumice.

I’m hoping this two component mix will lead to an easy gradation approach, adding a little more vermiculite to deciduous, very little to conifers. Of course it probably will not work that simply, but I’d like to try.

Thanks for reading and hopefully responding.

 

[cmeg1]

I imagine that vermiculite will run straight to the bottom after several waterings and not a good deal ......I would go with orchid bark and pumice........ top dressing of spagnum moss(orchid Moss) shredded . I shred the orchid moss very fine and it essentially turns into a disc in the pots,a top layer ,when it dries out every day.
I go 50-50 perlite and bark in quite small pots and a half inch layer of Spahgnum moss 1/2 inch on top does fine and blazing sun water once a day maybe twice

Orchiata bark is available on Amazon in different grades.Great bark.

 

[Punky]

As I said in the top post, I will be trying bark, but I also want an all inorganic option.

Vermiculite floats. I used some vermiculite with pumice for rooting cuttings last month and maybe some washed out, but there’s still quite a lot in there as I saw when I was checking my cuttings for roots today. It also was not congregated at the top, and I did not have drainage issues, so I think the vermiculite gets caught up in the pumice pores just right to not move too much without clogging them. Vermiculite tends to “stick” to my wet hand, so that may be part of it. I’m sure there is some movement, but it didn’t seem to be a problem last month.

Granted, that was a short test in several very small pots, but if it was an immediate problem as you suggested, I think I would have seen a hint of it.

 

[Cristian D.]

If you can source it, you can add seramis to the pumice. It is fired clay, good water retention and good CEC.

 

[Sekibonsai]

Vermiculite turns to slime and causes root rot. The current Akadama substitute for consideration is DE - probably simplest source is the NAPA oil dry option.

 

[jonathanvperth]

Grr

I imagine that vermiculite will run straight to the bottom after several waterings and not a good deal ......I would go with orchid bark and pumice........ top dressing of spagnum moss(orchid Moss) shredded . I shred the orchid moss very fine and it essentially turns into a disc in the pots,a top layer ,when it dries out every day.
I go 50-50 perlite and bark in quite small pots and a half inch layer of Spahgnum moss 1/2 inch on top does fine and blazing sun water once a day maybe twice

Orchiata bark is available on Amazon in different grades.Great bark.

Great advice!!! Thanks for the nice photos too!! I’ll be trying that top layer technique