Chinese Elm help. Dropping leaves

[mrt]

Good day dear bonsai friends

I have not written any forum posts since longer time since I first was sick for quite a while and then on a long vacation. But have always been watching the forums a bit. And now I am back and I enjoy the spring time and of course my bonsais!
However, I have just now realised a problem with my chinese elm!
So I have this elm since 2022 (see the first picture).

I then transplanted the elm in a larger pot with new substrate, I always use some volcanic gravel sort of thing, that has worked very well as it drains very well and usually the plants don't mind if a bit of water keeps sitting in the saucer under the pot. Also, often we have sometimes the discussion about if chinese elms can tolerate frost. Mine is very frost tolerant, in face, I keep it outside here in Switzerland all year round and in winter it gets in my place around -15°C and usually the tree will also be covered in snow, and it does not mind. Because now is spring, the tree starts to sprout, and as I was just checking all my bonsais, I noticed that my little elm has dropped some of its beautiful fresh green leaves! in fact, if I shake the tree, it drops a lot of leaves, but as you can see from the pictures, there is also some new growth.
Even though the tree is maybe not beautiful in classical bonsai standards, I like it a lot and am now worried it has some sickness or is dying.
So the problem is: the past few weeks, we had beautiful spring weather with lots of sun and during the day even very warm. So the trees sprout like crazy. We have now had the past couple days a bit of a come back of the cold; no frost at all, but just no sun and lots of rain. Due to bad luck, I forgot to empty the saucer under the pot of my elm so it was standing for a couple days in water. Usually, with the volcanic gravel as substrate, this does not matter. But still, I am now super worried that something is not okay, but I cannot determine what could be the problem.
I also have to say that I added the moss on top of the substrate like 2 weeks ago cause I have discovered some nice moss on a wall nearby and found the moss would look quite cool. Could it be that the tree dislikes the moss? but I believe then it would have started dropping leaves much earlier?
Or maybe it was just because it was a bit too wet?
Or, I hope, it was just that it is not so happy about the cool weather?
What is your experience with the chinese elms dropping leaves. Here are a couple images of my elm:


For comparison, I have a couple other bonsai; I have a field maple, that has no moss on the substrate but basically also grows in the volcanic gravel. No problem for him, the saucer is also often filled with water and the tree grows like crazy.
I also have a pear tree, where I also put some moss, and this tree also grows in the gravel and seems to be super happy. For reference, here is my pear, which looks good to me (please ignore my ugly construction with the strings, these are to correct the positions of some branches, as I prefer strings over the wires.)



So. I desperately hope you can help me with my little elm. I am very worried, cause I love it a lot and don't want to lose this poor little thing. Also I find it beautiful and it took a long time until it became like this.

Thanks for ANY hint!

 

[Wires_Guy_wires]

Hmm weird, I don't know what the cause would be, but some people treat moss with stuff like Roundup or worse, and that might lead to leaf drop if you move the moss to your pot. Pears might just be more resistant to those chemicals (manufacturers need that to be the case; otherwise orchard owners will not use it).

I would remove the moss and look for moss elsewhere. The type seems to be the right type for bonsai pots, walls and roofs are the best spots for that.

It could be a single shock event that made it drop that foliage. If the newly emerging foliage also starts dropping, it's time to investigate further.

 

[mrt]

Hmm weird, I don't know what the cause would be, but some people treat moss with stuff like Roundup or worse, and that might lead to leaf drop if you move the moss to your pot. Pears might just be more resistant to those chemicals (manufacturers need that to be the case; otherwise orchard owners will not use it).

I would remove the moss and look for moss elsewhere. The type seems to be the right type for bonsai pots, walls and roofs are the best spots for that.

It could be a single shock event that made it drop that foliage. If the newly emerging foliage also starts dropping, it's time to investigate further.

yes I checked and so far, it seems that the newly emerged leaves are still firmly attached. So maybe it was just a single shock from the sudden cooling? is that possible?
I will remove the moss and will see if it helps. I hope my tree is not dying.

 

[Wulfskaar]

A few years ago, I had the leaves on my 1 year old (at the time) chinese elm get spots, then turn yellow and fall off. Not quite the same, but a new flush of leaves grew in just fine and it hasn't looked back since.

Since it's so early in the growing season, I think/hope it will have no problems pushing out another set of new leaves.

 

[Topdec]

I keep my Chinese elm outside all year and it usually keeps its leaves until the new buds appear in spring then tends to drop the older leaves as the new ones grow!

 

[rockm]

yes I checked and so far, it seems that the newly emerged leaves are still firmly attached. So maybe it was just a single shock from the sudden cooling? is that possible?
I will remove the moss and will see if it helps. I hope my tree is not dying.

Cooling is not a problem unless it get below 32 f 0c. Chinese elm is very hardy outside. I have never shielded them from cold by bringing them them induring the winter.

This looks to me like the roots either dried out or were kept too wet. A saucer that collects water in not a good idea. It can keep things too wet.

Best thing to do is get it out of the saucer and keep the soil damp but not soggy. Don’t be tempted to bring it in leave it outside in morning sun and let it grow.

 

[Shibui]

Agree that the symptoms appear to be either too dry or too wet. Adding moss is just coincidental and not the cause IMHO.

Many people do not allow for the changes inside the pot caused by root growth over time. Reading between the lines it appears you may have had this tree for a few years? Over time, root growth gradually fills the spaces in the pot with more and more roots. Those roots occupy the spaces where water previously was, meaning the tree now has access to less water each day but we still water the same as last year. result is tree dehydrates even though we are still watering as before.
This pot is ideal to slip the root ball out and check how it looks. If you find masses of roots I would try a repot to rejuvenate the root ball. Now should be an ideal time to repot Chinese elm for you.

As mentioned above, too wet can cause the same problems because roots rot and can't take up the water so tree dehydrates. Checking the roots should show if roots are healthy or rotting. In case of root rot, also repot with fresh clean potting mix and don't sit pots in saucer with water.

 

[mrt]

Yeah I know the saucer is not a super good idea if the water stays there for too long. I have removed it yesterday and the tree is now without saucer.
However it is still raining a bit, so of course the tree gets some raindroplets and therefore also the soil/gravel cannot dry completely.

I will check the tree this afternoon when I come back from work and see if I can put it in a new pot.
According to the general experience: if the tree starts losing some leaves, is it usually possible that it recovers or did I just lose my little elm?

@Shibui yes I have this tree for 3 years now approximately. First it came in a bonsai pot but I thought this is too small and I wanted to give it more room to grow, so I moved it to a comparably large pot with fresh soil. As I said in the intro text, I normally don't use soil but some sort of volcanic gravel as this does not decompose easily like normal soil, and is also less prone to overwatering cause the water drains normally very fast. My other plants like the gravel and have nice and good rootballs.

@rockm
Yes I will not bring the tree inside. I never did, I find it a bit ridiculous that some people announce the chinese elm as "indoor bonsai". It is not, as I have experienced, mine stays outside all year and gets also some frost and will be covered in snow in winter.
Unfortunately at the moment we have had already a couple rainy and cool days, despite it is spring. So I cannot let the tree enjoy the spring sun, unfortunately. I hope next week will be a bit better.

Okay, so I think we conclude that maybe the tree was too wet and has some root issue. I will try to unpot today when I come home and check the roots. Fingers crossed that it is not beyond rescue! I don't know how resilient chinese elms are.

 

[rockm]

Yeah I know the saucer is not a super good idea if the water stays there for too long. I have removed it yesterday and the tree is now without saucer.
However it is still raining a bit, so of course the tree gets some raindroplets and therefore also the soil/gravel cannot dry completely.

I will check the tree this afternoon when I come back from work and see if I can put it in a new pot.
According to the general experience: if the tree starts losing some leaves, is it usually possible that it recovers or did I just lose my little elm?

@Shibui yes I have this tree for 3 years now approximately. First it came in a bonsai pot but I thought this is too small and I wanted to give it more room to grow, so I moved it to a comparably large pot with fresh soil. As I said in the intro text, I normally don't use soil but some sort of volcanic gravel as this does not decompose easily like normal soil, and is also less prone to overwatering cause the water drains normally very fast. My other plants like the gravel and have nice and good rootballs.

@rockm
Yes I will not bring the tree inside. I never did, I find it a bit ridiculous that some people announce the chinese elm as "indoor bonsai". It is not, as I have experienced, mine stays outside all year and gets also some frost and will be covered in snow in winter.
Unfortunately at the moment we have had already a couple rainy and cool days, despite it is spring. So I cannot let the tree enjoy the spring sun, unfortunately. I hope next week will be a bit better.

Okay, so I think we conclude that maybe the tree was too wet and has some root issue. I will try to unpot today when I come home and check the roots. Fingers crossed that it is not beyond rescue! I don't know how resilient chinese elms are.

If you up potted the tree into a larger pot and added a different freer draining soil without root pruning and purging old soil from the existing root/soil mass you have created a problem for the roots. Roots don’t like to cross the boundaries of different soil types.
That means roots are likely avoiding growing out from the root mass and remaining in the old soil circling around and clogging drainage even more

The old soil retains more water and stays wetter than the new. Watering in that situation can lead to root death as the inner soil remains wet yet the outer layer looks dry. You see the dry and think the tree needs water

The remedy would be a repot but it’s past optimal time for that. You will probably have to wait until next spring to take the tree out prune the roots purge the old soil from the root mass and replace with uniform soil mix

Elms are tough and resilient and can take that kind of treatment

 

[Shibui]

Fingers crossed that it is not beyond rescue! I don't know how resilient chinese elms are.

Chinese elms are very resilient. The healthy green buds show it is trying to grow. Yours has every chance of recovering from this small setback if you can find the cause and stop it happening again.

I have this tree for 3 years now approximately.

My other plants like the gravel and have nice and good rootballs.

I'm sure the Chinese elm likes your gravel mix too. Chinese elm roots grow much faster than Pear. Chinese elm could easily fill a pot and become root bound in 3 years. Every tree grows at different rates so comparing different species does not help diagnose problems.
Look forward to the results when you check the roots.

 

[mrt]

Good day dear bonsai friends

so I have now removed the moss and took the elm out of the pot to see how the rootball looks like. See the pictures attached!
I had in the past once root rot on a plant and there it had a funny smell coming from the root ball. However there is no smell on the elm, it smells just like humid soil/gravel. So I think there is no root rot.
However I agree the roots look a bit on the dark side, and of course the root ball is too congested, but I see that the elm has fully populated the entire gravel mix with roots, so I think it should be repotted.
Unfortunately, today is a holiday and shops closed, but tomorrow I can go to a shop and purchase a larger pot. The question is, if now would be a wise time to repot a bit. I guess I could quite safely cut off the lower part of the root ball on the very bottom?

But I am not sure. I normally would not repot at this time, is maybe already a bit late.

 

[Shibui]

The roots do not look too badly congested IMHO, and appear healthy enough.
I'd say no problem repotting now, especially as the tree only has new leaves. Growers in warmer areas find that Chinese elm never drops leaves so they do not have 'dormancy' to guide repotting time. They tell me they repot Chinese elm any time of year with no problem - whether the tree is growing or not growing.
My experience with repotting Chinese elm is a bit later is better than a bit too early so I'd say you should be Ok to repot this week, even if it is later than usual.

 

[leatherback]

I vote there is nothing wrong with your elm. It is early spring. The elms that stayed outside in winter are now pushing new growth and any leaves from last year will slowly (or faster) drop as the new growth comes in. I get this every year on mine. They look scruffy after winter, only to push a new flush and look lush again. During a temporary cold spell young leaves droop a little as the tree preps itself for potential unexpected frost. (It is what I see on mine in any case).

I would just wait for a week or two and see what a few days of warmer weather do..

The roots look fine.

 

[mrt]

Very nice! so you would also say the tree is okay, right? cool! I wonder why then he dropped some leaves.

I vote there is nothing wrong with your elm. It is early spring. The elms that stayed outside in winter are now pushing new growth and any leaves from last year will slowly (or faster) drop as the new growth comes in. I get this every year on mine. They look scruffy after winter, only to push a new flush and look lush again. During a temporary cold spell young leaves droop a little as the tree preps itself for potential unexpected frost. (It is what I see on mine in any case).

I would just wait for a week or two and see what a few days of warmer weather do..

The roots look fine.

Yes but in my climate, the tree completely drops all leaves for the winter, so is completely naked. Then in spring produces new green leaves, and he started to drop some of these new green ones. This is why I was originally very worried. But I understand now that it was maybe just this short cold phase that the tree didn't like and it will be fine once the warm weather comes back.

Thanks a lot! :-D phantastic!