Deciduous trees not being very deciduousey?

SeanS

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Starting a separate thread following on from my discussion with @Shibui regarding my misbehaving Chinese elm.

I have a number of deciduous trees that aren’t losing their leaves, or are behaving strangely. It’s the middle of winter in the Southern Hemisphere and some trees haven’t lost their leaves or are actively pushing growth (albeit minimally).

My general question is how do I treat these plants? Most of them I'd like to repot in spring, but am unsure how to go about this if they're either not dormant, or are already pushing some new growth?

I have many other deciduous trees (JM, tridents, crepe myrtle) which have all gone dormant. Our winter temps this year have been mild, just above freezing at night and 18-20° C (65F-68F) during the day.

First up is this Chinese elm. It grew ok in terms of extension, but constantly had yellowing leaves that would fall off leaving only minimal leaves right at the end of its extended shoots. This is it today, still holding on to its few greenish leaves.

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Next up are 2 flowering quinces. The one is an air layer I took off the mother plant last season. I battled spider mites all season on all of my flowering quinces, with this one loosing all of its leaves towards the end of the season, but has now started leafing out again and is flowering too for the last 2 months. The mother plant is acting similarly, still pushing new growth in the middle of winter!

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The mother plant. (Don't mind the perlite, it's a top layer until I can repot it after some soil was lost recently)

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Here's another flowering quince that lost all of its foliage towards the end of the season, mostly due to spider mite damage. It too is pushing some new growth in places. You can see 3 leaves on one branch and there are new buds pushing in multiple places.

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Here's a small root cutting from the first elm. This one (and it's 2 similar siblings) have at least turned colour (the 2 other ones are bright red), but is still holding onto it's foliage in the middle of winter!

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Lastly a JM that started pushing 2 new shoots in autumn, but has gone dormant over the rest of the tree. What do I do with these tender new shoots?

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BobbyLane

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Chinese elms can be semi deciduous depending on location, i had one that never dropped its leaves over winter. those trees you have in those little pots, i would repot them whenever. going from one small pot to another small pot is no problem for elms. you can repot them when theyre pushing new growth. or transfer to another container when dormant it doesnt even matter.
 

penumbra

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Based upon the trees and the location I am not surprised. Your trees are confused. Even in my climate these three trees get confused. I am sure we will be seeing a lot more of this in a lot more places in the future. We are going to have to learn how to cope with it and develop new skills and rules as we go.
I think your plants will be fine. I do have one rule I have followed assiduously throughout my career in horticulture. I don't re-pot while a plant is flowering unless it is a very careful up potting.
 

SeanS

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Based upon the trees and the location I am not surprised. Your trees are confused. Even in my climate these three trees get confused. I am sure we will be seeing a lot more of this in a lot more places in the future. We are going to have to learn how to cope with it and develop new skills and rules as we go.
I think your plants will be fine. I do have one rule I have followed assiduously throughout my career in horticulture. I don't re-pot while a plant is flowering unless it is a very careful up potting.
When you say based on my location, are my trees confused because they are upside down?
🤣
 

jeremy_norbury

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Normal for Chinese elms.

You can take it and put it on a shelf in a shed and it'll drop all its leaves and go dormant.

I asked Corin Tomlinson one time "When do you repot Chinese elms?" and his reply was "Every day but Christma; even I need a rest"...
 

SeanS

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Normal for Chinese elms.

You can take it and put it on a shelf in a shed and it'll drop all its leaves and go dormant.

I asked Corin Tomlinson one time "When do you repot Chinese elms?" and his reply was "Every day but Christma; even I need a rest"...
I moved it to a more sheltered spot out of the sun 2 days ago so maybe that will help it go to sleep for a few weeks before it decides to get rocking for the season again. Thanks for the feedback @jeremy_norbury 👍🏻
 

jeremy_norbury

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I moved it to a more sheltered spot out of the sun 2 days ago so maybe that will help it go to sleep for a few weeks before it decides to get rocking for the season again. Thanks for the feedback @jeremy_norbury 👍🏻
Chinese elms don't even need dormancy - they just keep going as long as there's enough light. Mine grow new leaves regular as clockwork in spring, regardless of whether they still have leaves or were completely bald.
 

kevinlovett86

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Or more importantly, which way do toilets spiral when you flush them?!
My toilet has these sideways holes in the rim that guide the water anti-clockwise, but also, this is China, high toilets are a new thing and I think they’re out to break physics over here.

I visited my hometown Port Elizabeth that last winter 1BC (before covid) packed all jeans and long sleeved shirts and nearly died of the heat, so the winters are getting warmer/shorter depending on how you look at it.

On this side, my deciduous trees here would hang on to their leaves until the new buds pop and they only fall off just in time to make room for new growth.
 

Shibui

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I have already mentioned that Chinese elms are known to be semi-deciduous and in warmer areas do not lose leaves at all until the new shoots start. @jeremy_norbury has already pointed out that another bonsai grower says Chinese elm can be repotted any time of year which aligns with my info from warmer places here in Australia. If you can get over the fear of traditional growers predicting doom for repotting out of season the tree will be fine whenever you root prune. there is no need to move to dark or sheltered place to induce leaf drop. Just get on and repot.
i have also repotted Chinese elm after new shoots had started. The dire predictions of catastrophe did not eventuate and the trees have been fine afterward.

I have also had maples pruned late in the season that then held new shoots all through winter but they revert to normal the following season. My take is that they are still effectively dormant but just forgot to let the leaves go. You can prune or repot as normal. Just close your eyes and pretend the leaves are not there or cut them off first so the the tree is leafless. That may make it easier on you to do the repot.

A lot of our experienced growers repot flowering trees after flowering. That usually means the trees are growing but they still don't mind having some root pruning. Does this only apply to spring flowering plants? Why are they so different to other species? Many experienced growers have recently come on board with repotting in late summer or early autumn. Trees are still active so why is this a better time than spring? Over here we routinely repot Australian native species in late spring or summer when they are actively growing and they don't miss a beat. Why are Aussie plants so different to the rest of the world? My take, and I have done some trials to confirm, is that most trees are capable of coping with repot and root pruning even when they have some new shoots. I know it is hard to fly in the face of traditional bonsai teaching but in quite a few cases I have found the traditions less than the full truth.
 

BobbyLane

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Normal for Chinese elms.

You can take it and put it on a shelf in a shed and it'll drop all its leaves and go dormant.

I asked Corin Tomlinson one time "When do you repot Chinese elms?" and his reply was "Every day but Christma; even I need a rest"...
i take this a step further and apply it to most hardy trees without much issues.
 

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