So, I have 2 yamadori beech trees that I collected about a couple months ago. One is doing great in 100% pumice and an air pot. The other is about 80% pumice and 20% akadama (top layer). The only reason I went with akadama is because I ran out of pumice and I couldn’t get anything due to coronavirus. Well the 80% pumice was doing great to start. The leaves started to flush then about a couple weeks ago they started to die off. Not sure if I was over watering or under watering etc. I watered it the same time as the other beech and bonsai (about daily). I am just wondering if I should put the beech back in the ground or weather the storm. The cambium layer is still green and appears to be still alive. Thanks for all of your help!
Anthoney
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So the akadama retains water more than pumice. Do you water only as needed or on a schedule? Also the tree in the shallow pot may have had more roots removed and not able to take up water as rapidly as the one in the deeper container.
I have to stop myself everyday and check for moisture levels in individual trees to avoid overwatering!
I found myself watering because it was a pleasurable experience spending time with my garden. BUT, the overwatering was making the trees unhealthy and the fungus happy. 
Planting with layers of soil instead of a uniform mix will make watering and knowing when to water harder to do correctly. An aeration layer at the bottom is good, but with pond baskets or anderson flat you do not need it. Water and oxygen and a healthy root ball will determine if the plant survives and thrives. If you put it into the ground it is unlikely to be overwatered. To put the plant into straight pumice would make it unlikely to retain water. Nice find! Hope they recover.
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Hi @Anthoney. To get the maximum benefit from using airpots it is best if you use either pure coir or a mix. I have been using airpots from 1 ltr right through to 20 ltrs for 7 years now with huge success. I have experimented with different mixes and trees and believe me a coir based mix is best. For example, cotoneasters don’t like pure coir. they didn’t die but didn’t grow much either. Yews or Western Hemlocks don’t like airpots at all and all the roots remained in the centre, without air pruning.
My standard mix is 45% coir 45% jack’s magic potting compost and 10% grit. All my trees love this mix. I currently have 8 different varieties growing in aipots including, conifers deciduous and broadleaf evergreens. All doing fantastic. This mix allows for plenty of airflow throughout the pot, drains well and promotes rapid root (and top) growth. Plus by using coir based (which incidentally the manufacturer recommends using pure coir) you can fill up all the cones which promotes air pruning of the root ends and encourages more fibrous roots as the tree grows. I didn’t like using just coir as it stayed to wet and lots of liverwort grew…bad sign.
The one in 100% pumice will be in danger in the winter of frost damage (if you get frosts where you are) or drying out on a windy day as there is nothing to stop the wind blowing through the holes.
The one with the akadama top layer in my opinion hasn’t allowed the roots to breathe and the tree has been drowned. Akadama holds water in between the granules as well as absorbing it whereas coir and compost spreads the water throughout promoting really fine roots. You could try repotting it back into the airpot but with a coir based mix or back in the ground. Either way it will be touch and go sorry to say.
When lifting from the ground the tree is brim full of energy so using a airpot seed tray (with the right soil) virtually guarantees success. Here are some photos of a cherry I lifted in 2018. Note how few roots there were initially and after the first year.
