I bought a Japanese Maple 5 or 6 months ago from a trusted nursery. I'm based in the UK where temperatures are currently pretty cold vs. what we normally get in winter (roughly -3 degrees celcius).

It may not be clear from the attached picture but the soil (which I'm 90% sure is Akadama) has completely broken down, is retaining way too much water and clearly needs to be swapped out in a few weeks time.

I've repotted 5 or 6 of trees before but never a JPM and have never repotted out of soil that is in this sort of condition (i.e. completely broken down). My main question is should I be completely bare rooting the tree i.e. washing away all the old broken down soil or leaving a reasonable amount in place? Any other factors I need to take into account specific to repotting a JPM or factors I need to take into account given the condition of the soil I am repotting from?

Thanks!
Isa

I have the same experience with akadama. It breaks down completelly in just a few years. So now I am just mixing in a small portion of it until my stock is finished, then I will not use it anymore.

The good news is that broken down akadama is very easy to rince of by washing in a bucket of water. I bare root complettely and have not seen any negative effect on maples.

Great, thanks. I'm keen to bare root it and give the roots a proper clean up, good to know!

Does it drain well atm? Isn't it better to wait until early spring?

Yep, going to wait till early spring, just making sure I know what I'm doing ahead of then!

Nice.
And nice tree you have there by the way.

Bare rooting is not a good idea with any tree, Akadama is designed to "break down" that is the reason for using it. I use a mix of Akadama pumice and kiryu 1.1.1 I have found this to be very good. It has been quite cold for a few days, but not for long. There is plenty of time to re pot so don't be in a hurry. Maples should be left until the buds are opening before repotting.

That could have been in that pot for a long time 5 or 6 years or even more since the last re pot.

Lovely tree you have there!

Yes, so as the others have said, akadama does tend to break down and can lead to water logging and root rot if the tree is not repotted.

I reccomend to use fresh akadama soil mixed with pumice, and a bit of lava rock. The akadama holds water really well and slowly releases it when the roots require it.

All the best, show us how it comes into leaf in the spring!

Nick

The thing about using Akadama is always repotting young trees every 2 years, and old refined trees every 5 years.
Mixed with Pumice and Lava Rock, it holds.

Now, there are two "kinds" of Akadama, the cheap, soft - read BAD one - used mostly in gardens in Japan; and the hard, expensive Akadama - read GOOD one - used for bonsai.
Cheap vendors sell cheap akadama for bonsai, and it is a disaster.