So this is a long debated topic, but I was wondering what some of the experienced growers on this site think of it. I am trying to develop a good Juniper soil that is fast draining, but without any rocky inorganic material like turface, akadama, or decomposed garnet. I find that after years of being in a pot and becoming root filled, this material acts like a big block of concrete, and to repot it could be deadly to the tree. Now I'm not talking about repotting by cutting the edges off slightly all around the root ball, I'm talking about a traditional root pruning and repot.

Please feel free to give your opinions, and soil mix recipes. Thanks

Akadama is the best soil. If left for too long of course it will deteriorate, but most trees need re potting everu 2 to 3 years.

Akadama is not a soil though, it is a median, and alone is basically just hydroponics. I live in a very hot climate, and want to make use of beneficial fungi, and bacteria, so I want and need a partially organic soil mix.

just add a thin layer of compost on the top of your planted trees.the granular part of the soil allows the trees to produce feeder roots close to the tree and not all through soil like in the ground.turface and akadama are moisture and nutrient retaining materials. turface tends to dissolve and turn muddy quickly akadama is better...

when root pruning it is much the same as branch pruning ,one must develope a good compact root system. this takes a lot of time especially from non bonsai nursery stock.these plants have been left to grow in a big pot and are not regularly root pruned. they are grown to be put into the ground not chopped and put into a bonsai pot.

Mine are in 60% kiryu 40% akadama. (also the one on my avatar.)
Works perfect and why try to reinvent the wheel?
Junipers like poor soil kiryu is just that.
Akadama is only to hold enough water for the tree and it releases all excess water. Pro is that it also holds temperature in the pot. roots need a stable temperature not to cold to grow.
Kiryu barely holds water so it's mainly there for drainage as junipers don't like too wet roots too long.
You say you live in a warm climate so youl might need to water some more each day.
By the way Junipers also like the soil to almost dry out before watering again.
And yes akadama will deteriorate but like m5eaygeoff says most trees need a repotting every 2-3 years anyway.
They grow junipers in japan in akadama or mixed with kiryu and they have a growing season of 9 months. Also extreme heat and cold and after years of trying things they still use it.
My Junipers are in the same mix and are very healthy seems to work just fine.
I even have a old yamadori that's been growing in pure akadama for about 8 years now.
I will add kiryu when it's repotted next year but that's just because we have alot of rain here.

Here it is growing on akadama.

Akadama sure looks and sounds similar aside from size to the expanded clay pellets (hydroton) I use with my hydroponic juniper. How often does that tree need watering?

I live in Las Vegas Nevada, It gets up to 120 degrees F during the day and 100F at night. I assure you that with akadama I would have to set it up on an automatic drip system watering every hour, or soon would have a heap of fire wood. I need some organic soil in my mix to hold moisture. I water daily as it is.

Each to his own. I found here that I did not need the composted bark that I added for a couple of seasons. So I went back to Akadama, but I now also use a British product called Kyrodama. It is like a crushed rock best way to describe it and much cheaper than Akadama. I use about 40% to 60% Akadama. I use this for most of my trees, the only ones different are the Satsukis.
There must be as many soil combinations as there are bonsai growers so, if it is good for you stick to it.
Geoff.

It's a Big tree and at this moment in summer temperatures it just needs water one time a day. My smaller ones need water twice a day.
At his moment it's 90 degrees F and standing in the full sun from sunrise till 1 then from 3.30 till sundown.
I can imagine with Las Vegas temperatures you need to water twice a day and keep them out of the burning mid-day sun.
Have you thought about tropical plants as bonsai for your climate?

I have a shelter built with a shade cloth cutting 50% UV during the 3 hottest months of the year. I have been growing some tropical trees, but don't want my collection to be limited to just those. I have pines, junipers, ficus, citrus, Giant Sequoia, Dawn Redwood and some others in my collection. I just have to baby them in the summer. Im gonna order some akadama, and put a small starter tree in it, just to see how it does around here. I know akadama is hard to get for a reasonable price in the USA, especially paying for shipping. I have thought about it a lot more since starting this topic though, and agree that I need to move closer towards an inorganic medium.