Akadama and freezing temperatures

Hello, all,

I’m just starting to explore the use of akadama. It does sound like an excellent growing medium, from all I’ve heard and read.

But a bonsai professional who lives in a slightly milder climate downstate recently told me that he does not use akadama in the mix for any trees that will spend the winter outdoors in freezing temperatures. His reason: he has found that akadama holds enough water that when it freezes, not being fired, it is reduced to dust. And that does his trees no good. He has switched to a product called calidama for ponderosas, etc.

Has anyone else had similar experience with akadama? Is this its one significant weak point?

(BTW, I checked Ryan’s local climate: per the government websites, St. Helens, OR, does not get lows below freezing in an average year.)

St. Helens freezes, but just barely. It rarely stays below freezing for a full day but it does get cold enough snow pretty much every year.

I’m in Portland, which is basically the same climate but maybe a touch warmer, and I’ve found that a good quality akadama does well here and doesn’t breakdown from freeze/thaw cycles.

Appalachian bonsai has a video up on his YouTube channel where he has different soil mixes run through a series of freeze / thaw cycles. You might want to check this out for the actual effects on the soil.


I’ve been using akadama in my soil mixes for about 6 or 7 years. Living in upstate NY, my trees experience both long periods of being frozen solid as well as frequent freeze-thaw cycles. The trees I’ve repotted don’t show any evidence of akadama “turining to mush” as some claim. In fact, for trees repotted after 3-4 years I’ve found quite a bit of solid akadama particles in the old soil.

Maybe there are some brands that are more susceptible or an occasional “soft” batch.

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@Chris @treebeard55 there is indeed “hard” akadama which is of a better quality soil, more “solid”. More difficult to find in Belgium, even at expos in France like Saulieu, Trophy.

I use akadama, pumice and volcanic particles in the UK. Our winters vary but we have had some long freezes over the years and I never have a mush problem. I’m careful to buy hard grade and have witnessed a poor dusty batch when suppliers changed a few years back but fine again now.

I agree with you @Blown55. I live up near sunny Scunny and we often have days on end where it doesn’t thaw. I’ve never noticed a severe breakdown of akadama at all. What I tend to do if it’s been raining and a freeze is expected I will go round and pour out any excess water from those planted in akadama, I don’t bother with those in development and are in basic compost. This does help in preventing it becoming a solid block of ice. Bloody cold on the hands though…

Thank you all for the feedback so far. (More comments are welcome.) I would point out that my friend did not say his akadama turned to “mush” after freezing, but to “dust”.

I guess I will keep investigating.

I haven’t had akadama turn to mush/dust because of frost so far, my previous garden went down to -25C around 2008 or 2009.

I’ve had mediocre akadama turn sort of rubbery after a spell of hard frost post-repotting in late spring… but the akadama change was the least of my worries as that frost killed a large chinese elm I had just repotted.

Way back, I was told to purchase “double line” brand if my garden was exposed to frost on a regular basis. The akadama that went “rubbery” was from a “lineless” brand. I’m currently using Ibaraki akadama, which is similar to the old “double line”.

Most of my akadama is also the Ibaraki brand, though over the years I’ve bought other brands and they’ve been mixed together. I haven’t done any comparative studies on how the various brands hold up to our harsh winters, I just know I haven’t seen any evidence of significant “mush” or “dust” or whatever you want to call the breakdown that some seem to have experienced.

If you’re not sure - just get some and test it out using less important or nursery stock. Determine for yourself how well it performs in your conditions.

I can confirm that double line is pretty dope