Japanese hornbeam over watering or not enough ?

[Chris88bull]

Hi wondered if somebody could help . My Japanese hornbeam has started to get strange discolouring on the leaves ? There's so much different info on the internet it's hard to get a proper answer . I'll attach some photos . To give some context it receives about 5/6 hours of sun a day ( if not cloudy in the uk ) . It was repot in spring . I noticed a small part that had the beginning of root aphids but felt like I dealt with and eradicated it as has been growing well , lots of extensions and just suddenly it has dipped a little . Hopefully somone can help .

 

[Shibui]

Brown edges and black marks are classic dehydration signs. Yellow is probably something different - see below.
The trouble with diagnosing over/under watering from a distance is that the physical symptoms are similar. Both cause dehydration. Over watering because that sets up root rot then there are not enough roots to take up water so the tree dehydrates. Under watering obviously causes direct dehydration. You should be able to work it out by how often and how much you water and whether the soil has been kept very wet.
In my experience, symptoms showing in summer are 90% underwatering. In most places it is hard to keep pots wet enough through summer to get root rot going but I guess that could vary according to your local climate and conditions. BTW, adding a location really does help with most advice as so much of what we do is closely linked to season and climates - (Oh, I just noticed you have slipped UK in among all the other details where I did not notice it. Much easier for us to find location if you put it in your profile.)

Under watering is insidious. It can happen even when we are watering regularly. The longer a tree is in a pot the tighter the roots become which makes it progressively more difficult to get enough water into the pots. Every year that the tree is not repotted increases the chance of underwatering through summer.
Also dry potting soil is hard to re-wet. Water just flows around and through the soil and out of the bottom of the pots leaving the root ball still mostly dry. I have done autopsies on trees that died in summer and was very surprised to find the centre of the root ball dusty dry despite that I had been watering assiduously every day. That really bought home the message that watering is easy to do but difficult to master.
I now encourage newer bonsai growers to soak pots in a tub of water each week in summer to make sure they get properly wet each week, at least until they master watering.

There are also some species that just do not seem to be able to take up enough water to stop leaf burn on really hot days, even when there's plenty of water around the roots. Japanese maple is a classic example and I wonder if hornbeam could have the same problem as I believe they come from similar environments. Your UK climate and limited sun exposure will probably reduce chances of that. Just adding it to reinforce the difficulty of long distance diagnosis.

The yellow leaves look more like nutrient deficiency, especially as they are some of the oldest leaves and the tree appears to be still growing strong.

 

[WNC Bonsai]

Might be helpful to see a closeup of the soil. What kind is it planted in?

 

[Chris88bull]

Thank you for this information , extremely helpful , I've always tried to be more cautious of over watering than under watering , perhaps I've gone a bit too far with this tree , it's a large tree .

When it was repotted the previous owner hadn't repot in I imagine quite a few years as it was so rootbound ( never seen so bad ) I removed a large amount of root , was just circling the pot . Part of the rootball was left untouched tho as wanted to be on the safer side as it hadn't done a full year on my balcony so didn't want to stress it too much ya know . I do think it needs all the soil changing tho as the innner soil has completely broken down , it's in pure akadama and previous owner said the same.

I've completely submerged the rootball and will try this each week for a while .

I've opened up the canopy slightly ( removed maybe 30 leaves roughly ) to get some more light in and moved it where it gets a bit more flow too . I'll attach some photos of the repot and the base at the moment . Thanks again everyone x

 

[leatherback]

Instead of submerging, just water properly. Water till it drains at the bottom. Wait and repeat 15 minutes later.
Submerging just compacts the substrate creating all sorts of problems.

Pure akadama is one of the worst substrates I have come across after old decomposing organics.

 

[Chris88bull]

Ok thanks , how come probably the most regarded bonsai professional ( Ryan Neil ) swears by pure akadama ? Just asking , not saying it's true . Surely it's down to your own circustances ? Thanks for your help

 

[leatherback]

Ok thanks , how come probably the most regarded bonsai professional ( Ryan Neil ) swears by pure akadama ? Just asking , not saying it's true . Surely it's down to your own circustances ? Thanks for your help

I have absolutely no idea why anybody swear by the stuff.

 

[Chris88bull]

Sure , what's your reasoning I'm asking , do you have any data ? Testing , results to say why ? hope you see where I'm coming from as at the moment . I'd say as Ryan Neil has won awards and day in day out ( via streams and videos ) shows the the proof is in the pudding with his stock and collection you know .

 

[leatherback]

the most regarded bonsai professional ( Ryan Neil )

Disputable statement. Maybe most-publicized would be better.

swears by pure akadama

I do not follow him so I am not sure. But I doubt he swears by pure acadama and uses it in some mixed for for many species. I would make the bold statement that many coniferous species would struggle in pure akadama.

Anyway.
Here some alternative viewpoints from some pretty decent artists.

To Akadama, or not to Akadama? - Bonsai Empire

At Bonsai Empire we receive questions about Akadama, and its use for Bonsai soil, quite a lot. With the recent price increases, troubles in supply and proposed ...

www.bonsaiempire.com

 

[leatherback]

Sure , what's your reasoning I'm asking , do you have any data ? Testing , results to say why ? hope you see where I'm coming from as at the moment . I'd say as Ryan Neil has won awards and day in day out ( via streams and videos ) shows the the proof is in the pudding with his stock and collection you know .

250 trees; growing bonsai for going on 15 years without problems, and not encountering the problems that were forecast.
Not seeing any of the reasons why akadama is special hold up from a biological standpoint. Seen trees die that came to me in akadama and were not repotted, with the rootball one yellow ball of muck.

Besides that, repotting.. I need about 5 minutes to clean up a rootball, as my substrate is stable and does not fall apart. Great aid to me.

 

[rockm]

Sure , what's your reasoning I'm asking , do you have any data ? Testing , results to say why ? hope you see where I'm coming from as at the moment . I'd say as Ryan Neil has won awards and day in day out ( via streams and videos ) shows the the proof is in the pudding with his stock and collection you know .

Akadama is used for developed bonsai. It is meant to break down over time to increase root ramification--at least that's the theory. It performs well for the first year or so, then (depending on the grade of Akadama) it turns to sludge. People unfamiliar with that tend to not notice the drainage problems it creates at the end of the cycle. It is used best with conifers. It's also important to understand there are different grades of Akadama. Some break down very quickly, while others are fired in a kiln and last a long time. Western Suppliers sometimes (and mostly if they're unfamiliar with the stuff) don't make distinctions.

It's OK for some applications, but hardly all. It's also expensive.

In your situation, it's not worth it and possibly detrimental. Plain old regular bonsai soil--with some added organics and harder sharper ingredients like pumice, coarse sand, etc. can facilitate drainage while the organics retain moisture (Which is important for a deciduous tree like yours).

Bottom line, there is no reason to put this tree in pure Akadama. And FWIW, Ryan Neil is working in the Pacific Northwestern U.S. primarily with old, even ancient, collected Western North American conifers. What he says is applicable mostly to what he's working on, not deciduous species in the U.K.

Also, there is no hard data or research to back up any of what he says. Doesn't mean he's wrong. It means he's going with his gut on this stuff, like the rest of us. Also important not to mistake notoriety for "last word" expertise. Ryan is a tremendous talent. He knows a lot about bonsai and their propagation. He's also a very good marketing guy with wide exposure online.

 

[Chris88bull]

Completely fair enough , appreciate all these answers / views . It's great to have a decent conversation rather than someone just saying no haha . Appreciate you both . I would add about the akadama reasoning that the mix for conifers he uses is akadama , pumice and lava . All deciduous trees pure akadama ( mostly ) . I was looking at the kaizon mix . People seem to swear by it , reviews wise . Anyway again thanks for all your comments and help . Deffo gone off topic a bit but all helpful none the less . I've sprayed the tree with a anti insect / fungus product that is recommended for bonsai . And will monitor water closely . Can everybody agree it's dehydration ?

Thanks

 

[rockm]

Completely fair enough , appreciate all these answers / views . It's great to have a decent conversation rather than someone just saying no haha . Appreciate you both . I would add about the akadama reasoning that the mix for conifers he uses is akadama , pumice and lava . All deciduous trees pure akadama ( mostly ) . I was looking at the kaizon mix . People seem to swear by it , reviews wise . Anyway again thanks for all your comments and help . Deffo gone off topic a bit but all helpful none the less . I've sprayed the tree with a anti insect / fungus product that is recommended for bonsai . And will monitor water closely . Can everybody agree it's dehydration ?

Thanks

The problem with saying it's dehydration is that the symptoms for over hydration are the same for the most part. That's because in either situation, the roots have been compromised either through drying out or drowning. They die off. That means the roots in either case are no longer supplying moisture to the top of the tree.

If I were you, I'd skip trying to use fancy soils APL (Akadama, Pumice and Lava) is used for species that love free draining soil (conifers primarily). Your tree is a species that grows in areas that remain constantly moist, so using such a mix can lead to drying out too quickly. Deciduous lowland species appreciate a slightly richer mix that includes some organic content--pine bark, orchid bark (baby orchid bark which is smaller particles).

The mix from Kaizen I think you're talking about is a propriety mix by Kaizen (A vendor in the U.K.) I would avoid the mixes they sell that promote "superior drainage."

This one looks pretty decent for your application:

Premium Bonsai Compost No2 - General Purpose Mix With Biochar

Premium Bonsai Compost No2 -General Purpose Mix Suitable for most bonsai trees in pots larger than 10

www.kaizenbonsai.com

 

[Chris88bull]

ok cool . I'm unsure if this helps but as you can see it's in a wooden box and there's tiny gaps at the bottom edges and I can see fresh white roots . Unsure if maybe the air is getting to them too fast . Drying them out quicker ?.

You mentioned about they both show the same symptoms however by your example of the soil it should be in . if I'm using pure akadama we can maybe lean on the side that it's drying out rather than too wet ? Purely on the suggestions you're giving ?

Thank you this is very kind

 

[rockm]

ok cool . I'm unsure if this helps but as you can see it's in a wooden box and there's tiny gaps at the bottom edges and I can see fresh white roots . Unsure if maybe the air is getting to them too fast . Drying them out quicker ?.

You mentioned about they both show the same symptoms however by your example of the soil it should be in . if I'm using pure akadama we can maybe lean on the side that it's drying out rather than too wet ? Purely on the suggestions you're giving ?

Thank you this is very kind

This tree does NOT need pure akadama. The developing roots are a good sign. Stop worrying so much about air, akadama, etc. Get a decent general purpose deciduous bonsai soil mix and have it on hand NEXT SPRING WHEN YOU REPOT THE TREE. DO NOT repot it this summer. You've already stressed it with the repot/root pruning out of season as things are.

 

[Ruddigger]

I know that Ryan Neil does use 100% in his deciduous. I have as well with good success, as well as with my thirstier conifers like Cost Redwood. Although I’m starting to experiment by adding more lava every repotting until I see a degradation.

 

[Chris88bull]

This tree does NOT need pure akadama. The developing roots are a good sign. Stop worrying so much about air, akadama, etc. Get a decent general purpose deciduous bonsai soil mix and have it on hand NEXT SPRING WHEN YOU REPOT THE TREE. DO NOT repot it this summer. You've already stressed it with the repot/root pruning out of season as things are.

Thanks , yeah don't worry I'm just here for the discussion and wisdom , I've been doing bonsai for 6/7 years I'm well aware we don't repot in the height of summer haha . Thanks

I'm also not worried about the pure akadama situation more the discolouring in my leaves that the original post was about . The topic just went a bit that way when someone advised it's no good is all .


Thank you for all you're advice let's hope the colouring in the leaves sorts it self out

 

[Shibui]

if I'm using pure akadama we can maybe lean on the side that it's drying out rather than too wet ? Purely on the suggestions you're giving ?

The few times I used Akadama I found that it did NOT dry out properly. Those trees in akadama had root problems from staying way too wet so I no longer use any akadama.
I guess there must be management techniques and watering regime that would suit but it does not work under my current care arrangements.

 

[Chris88bull]

just an update , quite sure it was dehydrated as left it for a few days to dry out , the core rootball is very dry ( drys out quite quick ) and looks like lots of the leaves got scorch ? Also some curling but no wilting so pretty sure that's under watering ? Thanks everyone