Chinese Elm questions and wintering

[AmazingUnicorn]

Quick back story. Picked up a Chinese Elm in Malibu in December. Looks like it spent most days outside but it never lost its leaves so I brought it back to Chicago and it's kept in a part of the house that's about 70f with grow lights that I ran for 6 hours but have changed to 12 in the last few days. Few questions.

1. I noticed that the soil seems not totally dense but not the Pumice or more coarse soil that I see for most bonsai. It's much closer to what I'd call "house plant soil". I picked up some new soil from The Hidden Gardens here in Chicago that seems to specialize in bonsai but I understand I can't change it out during winter. Any suggestions in the meantime? Water less often? Now I wait for the soil to feel on the dry side since it holds water.

2. The tree has started turning some leaves yellow and dropping them. Is that just because of the change in conditions? I think I was over watering at first doing it about every 3-4 days. It was a bit more full when I initially brought it back.

3. Has anyone used these grow lights and have any positives or negatives? https://www.amazon.com/gp/product/B07QNHTZ9C/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

 

[Zach Smith]

1. You don't have enough experience with this tree to understand its environmental requirements indoors, so your best guess of giving it plenty of light and not overwatering is about as good as you can do. Remember that if the tree is not actively growing it won't take a lot of water, and may prefer to be dormant despite your attempts to give it plenty of light and warmth.
2. This is normal due to change of growing conditions. It came from Malibu to Chicago, from warmth and light to cold and less light, and really doesn't know what to think at this point. Yellowing and dropping leaves is normal under these circumstances.
3. Can't answer this one, since I don't grow trees indoors.

The best thing you can do for this tree right now is to put it in an unheated space and try to give it a little dormant time. Then when spring comes around, outside it goes! Chinese elm is not a tropical species. The fact that the species can be maintained indoors under carefully controlled conditions leads many to believe they can be kept indoors all the time. The vast majority die under these circumstances.

 

[AmazingUnicorn]

1. You don't have enough experience with this tree to understand its environmental requirements indoors, so your best guess of giving it plenty of light and not overwatering is about as good as you can do. Remember that if the tree is not actively growing it won't take a lot of water, and may prefer to be dormant despite your attempts to give it plenty of light and warmth.
2. This is normal due to change of growing conditions. It came from Malibu to Chicago, from warmth and light to cold and less light, and really doesn't know what to think at this point. Yellowing and dropping leaves is normal under these circumstances.
3. Can't answer this one, since I don't grow trees indoors.

The best thing you can do for this tree right now is to put it in an unheated space and try to give it a little dormant time. Then when spring comes around, outside it goes! Chinese elm is not a tropical species. The fact that the species can be maintained indoors under carefully controlled conditions leads many to believe they can be kept indoors all the time. The vast majority die under these circumstances.

1. You don't have enough experience with this tree to understand its environmental requirements indoors, so your best guess of giving it plenty of light and not overwatering is about as good as you can do. Remember that if the tree is not actively growing it won't take a lot of water, and may prefer to be dormant despite your attempts to give it plenty of light and warmth.
2. This is normal due to change of growing conditions. It came from Malibu to Chicago, from warmth and light to cold and less light, and really doesn't know what to think at this point. Yellowing and dropping leaves is normal under these circumstances.
3. Can't answer this one, since I don't grow trees indoors.

The best thing you can do for this tree right now is to put it in an unheated space and try to give it a little dormant time. Then when spring comes around, outside it goes! Chinese elm is not a tropical species. The fact that the species can be maintained indoors under carefully controlled conditions leads many to believe they can be kept indoors all the time. The vast majority die under these circumstances.

Thanks Zach. The coolest place I can put it is in the basement which is maybe 60-65 down there.

Believe it or not, through a good chunk of December Malibu was quite cool and a few days Chicago was way warmer!

 

[Deep Sea Diver]

First off, if it’s a true Chinese Elm, it’s a very tough tree. Second I think it’s best if your Elm goes dormant. At this time of the year one way is to wean it to outside conditions during the day. Bring it in to the basement at night and when it’s below 45 to start with and slowly lengthen the time it’s outside and the temps it’s exposed to down to freezing. Keep it moist but not wet and protect it from the wind to start with. It ought to drop it’s leaves after a bit. The goal is to get it into dormancy (likely happen below 45ish) for at least six weeks, 8 would be much better. (Do you have an unheated garage? It would be better than the basement.
Here’s a bit of information on your Elm, Ulmus parvifolia. (Wikipedia) It is one of the cold-hardiest of the Chinese species. In artificial freezing tests at the Morton Arboretum the LT50 (temp. at which 50% of tissues die) was found to be −34 °C (−29 °F).
Good Luck! DSD sends

 

[AmazingUnicorn]

First off, if it’s a true Chinese Elm, it’s a very tough tree. Second I think it’s best if your Elm goes dormant. At this time of the year one way is to wean it to outside conditions during the day. Bring it in to the basement at night and when it’s below 45 to start with and slowly lengthen the time it’s outside and the temps it’s exposed to down to freezing. Keep it moist but not wet and protect it from the wind to start with. It ought to drop it’s leaves after a bit. The goal is to get it into dormancy (likely happen below 45ish) for at least six weeks, 8 would be much better. (Do you have an unheated garage? It would be better than the basement.
Here’s a bit of information on your Elm, Ulmus parvifolia. (Wikipedia) It is one of the cold-hardiest of the Chinese species. In artificial freezing tests at the Morton Arboretum the LT50 (temp. at which 50% of tissues die) was found to be −34 °C (−29 °F).
Good Luck! DSD sends

Thanks DSD! Question about dormancy. You don't think it's late in the season to do so? When I was at the local bonsai seller (Hidden Gardens outside of Chicago, not the one I bought it from) he said to not worry about it at this point. He felt it was a bit late. I'm open to either.

By the way, if I put it in the garage, still light it or not bother?

 

[Deep Sea Diver]

Hmm.... I think it will be the best for the tree if it even gets a shortened shot of dormancy. Otherwise the tree will break bud early and actually be weakened. Also its day night cycle is messed up. So keep it outside as much as possible, starting off for a couple 4 hours and work up to full days and even nights if the temps will allow over 2-3 weeks if conditions permit.
If the tree is inside the garage, you should mimic the amount of daylight that it would get in Chicago. Since its all messed up right now, it would be better to get it back to its local routine and harden it off. Try not to stress it too much Winter is one month in. Part of dormancy depends on the amount of light the plant gets per day and also temperature and sometimes drought. So set your lights on if its in the garage to mimic what it will get on the outside if the tree is inside during the day. Better still put it near a window... not too close though so it doesn't get fried.
Here's a good article summarizing the situation. Its from a newpaper, but written with input from Foresters.
https://www.fredericknewspost.com/n...cle_f016be64-a169-5ba0-a1be-f38a33dbb0e2.html
BTW: Can you please edit your profile to put in your location and zone. It will help folks help you in the future and when you pay it forward, it will help those you are helping.
Cheers DSD sends

 

[Zach Smith]

Thanks Zach. The coolest place I can put it is in the basement which is maybe 60-65 down there.

Believe it or not, through a good chunk of December Malibu was quite cool and a few days Chicago was way warmer!

I hear you! We have similar problems, though we're far apart. I have some Chinese elms waking up due to a few 70+ degree days in January, then it got near freezing a few mornings, now it's in-between so some things are budding and others not. The main thing with your guy is the indoor siting. Chinese elms take a pretty remarkable amount of cold. So barring really cold weather, I always recommend leaving them outside. Whenever you bring any tree indoors, you've given it a huge survival challenge and this goes doubly for species that do best with a dormant period.

 

[Silentrunning]

I am in North Carolina Zone 7b. My Chinese Elms go into one of those cheapie $25 plastic green houses. If it is predicted to get below 20f I throw a blanket over the green house. I haven’t lost one yet.

 

[rockm]

Thanks DSD! Question about dormancy. You don't think it's late in the season to do so? When I was at the local bonsai seller (Hidden Gardens outside of Chicago, not the one I bought it from) he said to not worry about it at this point. He felt it was a bit late. I'm open to either.

By the way, if I put it in the garage, still light it or not bother?

It is too late in the season for dormancy. Getting the tree to limp through inside until spring is the way to go.

You will not be able to induce natural dormancy by moving it in and out of light sources. You could make things worse by constantly moving the tree.

Dormancy is a very gradual process that takes months in full sunlight to achieve. You simply cannot mimic "natural" conditions to induce dormancy in the tree without putting ALOT of effort into it that will probably not be effective.

At this point, I'd keep it in a bright location inside away from cold drafts. I'd watch the watering and let it dry down a bit before watering.

Come normal spring in your area, I'd get it outside ASAP when temps are reliably above freezing. I'd leave it outside from that time on for the rest of its life.

 

[Anthony]

Leo has it stated as a zone 4 to 5 tree,
In a pot. it maybe zone 6 or 7.
China has them growing in zone 9 to export as -FAKE - indoor plants
Buyer be ware,

The ones that came fom Canada - died down here.
Good Day
Anthony

Maples take 4 years to die down here with no dormant period.
Tropics

 

[sorce]

be

I was thinking of all these typing about the "natural naturally" conditions these subtropical trees are facing this warm year.

@AmazingUnicorn
I believe they are subject to the phenomenon we are talking About here.

Sorce

 

[Deep Sea Diver]

It is too late in the season for dormancy. Getting the tree to limp through inside until spring is the way to go.

You will not be able to induce natural dormancy by moving it in and out of light sources. You could make things worse by constantly moving the tree.

Dormancy is a very gradual process that takes months in full sunlight to achieve. You simply cannot mimic "natural" conditions to induce dormancy in the tree without putting ALOT of effort into it that will probably not be effective.

At this point, I'd keep it in a bright location inside away from cold drafts. I'd watch the watering and let it dry down a bit before watering.

Come normal spring in your area, I'd get it outside ASAP when temps are reliably above freezing. I'd leave it outside from that time on for the rest of its life.

Interesting . Could you please provide some data? From what I researched ornamentals and fruiting trees can go dormant with only somewhere between 500-700 chilling units, which is still possible. Also it appears that if trees don’t go dormant that their growth rates are adversely affected for the following year (delaying potential best
growth for at least year). Thanks for your help. DSD

 

[Krone]

I put my Chinese elm indoor during the winter. I put him inside at the end of autumn when temperatures drop bellow 15C/60F. Window shelve with plenty of sun.
This is the third year and the little tree survives with no problems. It drops some of the leaves when put inside, but it grows them back.

 

[rockm]

Interesting . Could you please provide some data? From what I researched ornamentals and fruiting trees can go dormant with only somewhere between 500-700 chilling units, which is still possible. Also it appears that if trees don’t go dormant that their growth rates are adversely affected for the following year (delaying potential best
growth for at least year). Thanks for your help. DSD

Disingenuous questions, huh? I don't have any data on dormancy in Chinese elms (but you knew that), but then neither do you.

Your research into dormancy for ornamental and fruit trees is nice, but, how many BONSAI CHINESE ELMS have you overwintered YOURSELF?

If you knew Chinese elms, you'd know they have mostly rather shallow dormancies, or are capable of enduring a winter indoors. Having overwintered Chinese elm bonsai for twenty years, I can say trying to induce dormancy in one at the end of January is useless. Trying to induce dormancy in a tree by gradually exposing it to less and less light over a week or two misunderstands the process. I've also fund that Chinese Elm winter hardiness can vary tremendously. Catlin and the smaller leaved varieties can see die off or outright death with temps under 20 for a few days. Had it happen...

It is not necessary at this point to try to push the tree into dormancy when spring is not far off. Keeping the tree inside under grow lights will get it through just fine.

 

[Deep Sea Diver]

Disingenuous questions, huh? I don't have any data on dormancy in Chinese elms (but you knew that), but then neither do you.

Your research into dormancy for ornamental and fruit trees is nice, but, how many BONSAI CHINESE ELMS have you overwintered YOURSELF?

If you knew Chinese elms, you'd know they have mostly rather shallow dormancies, or are capable of enduring a winter indoors. Having overwintered Chinese elm bonsai for twenty years, I can say trying to induce dormancy in one at the end of January is useless. Trying to induce dormancy in a tree by gradually exposing it to less and less light over a week or two misunderstands the process. I've also fund that Chinese Elm winter hardiness can vary tremendously. Catlin and the smaller leaved varieties can see die off or outright death with temps under 20 for a few days. Had it happen...

It is not necessary at this point to try to push the tree into dormancy when spring is not far off. Keeping the tree inside under grow lights will get it through just fine.

Wow... I actually was honestly in search of concrete information. Also I don’t think that there is no data out there on the subject. Being newer to the Bonsai blog, but not new to trees and plants, I thought that the sources here were both learned sources of information and a well of practical wisdom... both of which I prize. However with both a scientific and practical background myself, I like to keep a fine balance between the two, especially considering that there are vast temporal and climactic differences between the participants as well as in the conditions that the trees are being kept in.
That said, does anyone else out in Bonsai Nut land have data on dormancy requirements of Chinese Elms?
(Here is a general article on dormancy that I found so far, Winter dormancy in woody plants.)

 

[rockm]

Wow... I actually was honestly in search of concrete information. Also I don’t think that there is no data out there on the subject. Being newer to the Bonsai blog, but not new to trees and plants, I thought that the sources here were both learned sources of information and a well of practical wisdom... both of which I prize. However with both a scientific and practical background myself, I like to keep a fine balance between the two, especially considering that there are vast temporal and climactic differences between the participants as well as in the conditions that the trees are being kept in.
That said, does anyone else out in Bonsai Nut land have data on dormancy requirements of Chinese Elms?
(Here is a general article on dormancy that I found so far, Winter dormancy in woody plants.)

If you were honestly in search of info, I apologize. That is rare here. Stick around you'll see.

As for the scientific data on overwintering bonsai, there is no such thing. This is the best source of this stuff around. There are several articles in there about overwintering. I tend to discount most formal academic studies on crops and timber. They're not all that useful in bonsai, since they're not containerized--which complicates overwintering bonsai.

Articles About Bonsai

 

[Deep Sea Diver]

Thanks for the apology, no worries! Affect is hard if not impossible to determine in text.

I’m a customer of Brent’s and have I’ve read through his articles previously and have just reread the statement in his article on dormancy “Subtropicals such as Chinese elms, Ulmus parvifolia, have little if any dormancy requirements” and have tried to hunt down its source to no avail. Instead I observed the quote repeated on the net multiple times. Perhaps Brent would enlighten us about the source of this quote. Thanks for pointing this out btw.

On the other hand I did find research on bud dormancy release on elms that appears to suggest a short dormancy was required for bud release with their estimate of 35 chilling days for the Chinese Elm and less for the European Elm (See Modelling analysis and chilling requirement estimates section). Also that Photoperiod seems not to be important for the release of buds for either of these trees.

Looking at the avg climatology for Malibu CA it appears that there are sufficient low temps (<45 or <50F depending on the models I saw.) in the winter to induce the short amount of dormancy needed in the Chinese Elm, as does Kelseyville, CA where I believe Brent’s greenhouse is located, as will many other places in North America.

Conclusion: I could be wrong in my interpretation and I’m open to other interpretations, but the literature suggests that The Amazing Unicorn should keep his Chinese Elm in cooler temperatures, perhaps outside during the day if in the 40s (given the input from the folks on the blog) and/or in the garage if the temperatures are suitable to attain sufficient chilling days in the next months rather than outside for the best health of the tree.

All other advice pertaining to proper watering by the folks here should also apply - dry the soil out a bit between waterings etc.
cheers
DSD sends

 

[Leo in N E Illinois]

@AmazingUnicorn
You have done one of the BEST THINGS for learning about bonsai. You have visited Hidden Gardens. Talking to Jeff and the rest of the staff, you can get excellent and CHICAGO AREA SPECIFIC advice on what to do with your Chinese elm. Hang out there often, you will learn much.

It is too late to induce dormancy, @Zach Smith was giving you pretty good advice. Note by cool, Zach meant cool but above freezing. @rockm advice is good, though a deeper dive than what you may have been looking for. When reading advice, always look at where the source of the advice lives. That will usually give you a clue as to the context or local weather effects the poster is used to dealing with.

If you have a large picture window, with a windowsill that the tree will fit on, the cool air falling off the glass will help keep your tree cool. Just stay on top of watering, you only have 2 or so more months to go before it can go outside.

Next year, you can summer your elm outdoors, and acclimate it over the autumn to our winters. My Chinese elms are in the back yard right now.

 

[Deep Sea Diver]

So there is science and there is wisdom. Sometimes they align, sometimes they don’t. Then there is opinion and assumptions which are different ducks all together. I prefer a blend of science and wisdom.
I actually am from Chicago, a proud graduate of Lane Tech class of’69 who also lived in Watertown WI and worked on my relatives farms there and have worked with native trees and shrubs for years. I now reside in Seattle. I have never assumed I am an expert, but have been known as a pretty good researcher and craftsman at times.
As far as what Amazing Unicorn should do, I’ll leave it to the Unicorn who has possession of the tree and also the responsibility for its health. The trees are starting to break bud already, if that’s the same in Chicago, the issue is moot anyways.
I really do appreciate the polite give and take in sharing information with others and am learning alot from and about each of the folks who participate on this blog. Bonsai Nut, to me, is a group designed to help each other convey the best data and wisdom possible so each of us can create the very best Bonsai. That said I’ve got a grafting question to pose as a different post!
Cheers
DSD sends

 

[Leo in N E Illinois]

Temperatures are hovering around 27 to 32 F (-2 C to 0 C ) pretty much the whole week. Not very cold at all by normal winter standards. Light drizzle, sometimes snowflakes, sometimes rain off and on all week. Everything outside is pretty much dormant. It has not been cold enough to get garages, storage sheds and my well house are all running warmer than normal. So some of us are having issues with trees swelling buds early. But if you tree is on the ground outside in the Chicago area, it is still completely dormant.