Soil Mix Adjustments


I am new here and this is my first post, so apologies if this has been covered. I watched Ryan’s video on soils and had a few questions:

  • How would you adjust the soil mix to different climates (I live in Boston)?
  • I get the default 1:1:1: mix. However, I work and can’t always water the trees at the perfect time or 2x per day on a really hot summer day. How would you adjust the soil mix to be more “forgiving” without negating the idea/balance behind the mix? Just add more Akedama or add an organic component?
  • Ryan never seems to use any organic components in his mixes. How come? What is the downside/advantages of adding something like 1/8" or 1/4" pine bark to the mix? Many “commercial bonsai mixes” seem to have that component.

Thank you in advance!


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The goal is to achieve a balance of water and oxygen in the container. Organic matter can compromise this. Ryan recommends adding 1/16” particle size into the mix to hold more water. As you mentioned he does recommend adding more akadama as well 2:1:1 for say deciduous trees. Adding top dressing should also aid in holding moisture as well. Between all three of those strategies the idea would be to achieve the watering rate your schedule requires without having to add organic matter.


I myself do add pine bark, but only to deciduous trees, and mostly tropicals. They grow so fast for me that I’m typically doing a repot by the time the bark begins to really break down. I’ll go 1:1:1:1 with bark on tropicals, and I’m using DE instead of akadama. I cut the bark ratio in half for the slower growers. Top dressing helps a lot, too. Moving the tree so that it’s only getting morning sun, but some shade in the afternoon helps it from drying too fast.

I would avoid adding soil, peat moss, or any fine organic though. It settles in the bottom of the container and turns to mud, killing a lot of your roots. Some folks do add a coarse sand, but I’ve never really had to, and my summers get into the 115°’s routinely.


Ryan Reccomends 100% Akadama for most deciduous trees, not 2:1:1. Big difference.

Also to answer the OP’s question about organics like bark, Ryan has said he doesn’t like to use pine bark because it decomposes too quickly. When you have conifers that might go 6 years between repotting, the bark decomposes too much and the soil becomes soggy and you lose a balance of water and oxygen.

Another known horticultural issue with pine bark as a soil media is that, as it is decomposing it “steals” nitrogen from your soil which is obviously not good. You can read on how that works In this article . The bonsai world seems to continue to ignore this for some reason. To be honest I’m not sure if the effect is huge in bonsai culture where we are blasting the soil with fertilizers. But I choose to stay away from it for those two reasons.

Instead of using pine bark or something similar just use more Akadama or D.E. In your mix. And like the other guy said, using a thicker top dressing layer will help you a lot. I was doing some soil experiments last spring and I potted about 10 collected hawthorn into 100% perlite. Kind of a similar idea to potting yamadori in 100%pumice, tons of aeration for new roots. But 100% perlite dries out pretty fast in the heat of the summer, and so I just doubled up on the top dressing and they all ended up doing really well and top dressing really helped retain enough moisture on hot summer days.


You can buy composted pine bark which will reduce the nitrogen stealing effects. Most people I’ve seen recommend this when recommending pine bark as a soil additive.

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Can you share the video where Ryan is talking about this soil mix please

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Thanks for that timely refresher @MtBakerBonsai
Ryan mentions chabuzai/xeolite from a Canadian source as having some potential as a soil component. I believe it is now available in the USA and wondered if anyone was aware of further investigation.

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