ACTUAL" Hardening Off" - Please teach me about

[my nellie]

This is about a small collected Acer sempervirens or Acer creticum (Cretan Maple)
It was donated to me last January 2018 by a good friend who collected this specially for me.

This is a very sensitive species, slow in growth, "touchy" at being disturbed, local conditions dependent etc etc

The long tap root was a little further reduced and there were sufficient other roots and hairy roots.
I put it into a good draining substrate and a big bonsai pot, removed some of the unwanted branches and kept all foliage on.





During the next weeks all foliage was shed except some 4-5 leaves which remained green for a long time, until they died off.
No sign of a wish to give new buds/shoots for a long time. But the bark was alive!
The pot was enclosed into a transparent plastic bag so that humidity is retained/provided.

As of last March I decided to shift transparent bag to a black plastic bag. So I did and kept on misting it regularly.
It was not until this month of June that the tree decided to take a deep breath and come back to live!



For the time being there are not new shoots on primary branches but only on the two trunks.
I hope there will be more to come.
It is still into its clear plastic bag and placement is in a location protected from direct sun exposure.

Question : How do I help the tender shoots to harden off?

Of course, I have some notion/plan in my mind but I would be grateful for your experienced view/suggestions.

Thank you in advance!

 

[KiwiPlantGuy]

This is about a small collected Acer sempervirens or Acer creticum (Cretan Maple)
It was donated to me last January 2018 by a good friend who collected this specially for me.

This is a very sensitive species, slow in growth, "touchy" at being disturbed, local conditions dependent etc etc

The long tap root was a little further reduced and there were sufficient other roots and hairy roots.
I put it into a good draining substrate and a big bonsai pot, removed some of the unwanted branches and kept all foliage on.

View attachment 196413View attachment 196415

View attachment 196414 View attachment 196416

During the next weeks all foliage was shed except some 4-5 leaves which remained green for a long time, until they died off.
No sign of a wish to give new buds/shoots for a long time. But the bark was alive!
The pot was enclosed into a transparent plastic bag so that humidity is retained/provided.

As of last March I decided to shift transparent bag to a black plastic bag. So I did and kept on misting it regularly.
It was not until this month of June that the tree decided to take a deep breath and come back to live!

View attachment 196417 View attachment 196418

For the time being there are not new shoots on primary branches but only on the two trunks.
I hope there will be more to come.
It is still into its clear plastic bag and placement is in a location protected from direct sun exposure.

Question : How do I help the tender shoots to harden off?

Of course, I have some notion/plan in my mind but I would be grateful for your experienced view/suggestions.

Thank you in advance!

Hi Alexandra,
My concerns are that you said this species of maple is “touchy” and unfortunately it seems like it didn’t like its roots be disturbed. Weird that it lost all its leaves as a destressing method (self- preserving).
The good news is that it is still alive, and over the next few weeks/months it might bounce back slowly, and then be ok to great next season. I wouldn’t prune anything til next Jan at the earliest.

To answer your thread title - in the nursery trade “hardening off” usually means placing plants outside from a greenhouse to get your soft inside growth hardened up to get it acclimatized ready for the summer etc.
if you have confused hardening off versus lignifying then different story. Lignifying is when your soft new growth gets a more stiff feel ( and won’t feel like snapping a pea pod or carrot). Or in other words when a stronger stiffer branch is snapped itwill sound quite loud in comparison. And cutting back to one to two buds after lignified growth (has stopped growing) to increase ramifications on the tree.
Hope some of that wee essay was useful. My 2 cents and all that.
Charles

 

[my nellie]

Thank you for your reply, Charles!

... ...To answer your thread title - in the nursery trade “hardening off” usually means placing plants outside from a greenhouse to get your soft inside growth hardened up to get it acclimatized ready for the summer etc. if you have confused hardening off versus lignifying then different story... ...

This is the reason why I named the title Actual hardening off
What are your thoughts about methods for getting the tree acclimatized?
I am thinking of opening the bag for some hours during daytime and perhaps the whole night through...

 

[just.wing.it]

Since were back on this topic...
As kiwi said...the process of Hardening Off in gardening in general, is moving plants from indoors to outdoors to slowly acclimate the foliage to the sun.

More recently, some people in the bonsai community have used the same terminology to describe the formation of the cuticle on new leaves, when they go from a light green color to a dark green, and become stiffer.

Maybe there should be a better term to use, so people dont get confused....because its confusing...

To throw another wrench into the gears, we have Lignification!
Lignification is the depositing of Lignin in cell walls of a plant to create wood.

Now, leaves are not wood...so can lignification really be used to describe the process of the formation of the cuticle???
I'd have to say no, based on that...
But is lignin also present in the leaves???...this I don't know exactly...

 

[my nellie]

Thank you for your input @just.wing.it !

However, I'm afraid I failed to pass my message through to you people.

What I was aiming at when creating this thread is the method (if any) to gradually/slowly acclimatize the new tender foliage to the sun.
For example, I said above that I intend to open the bag for some hours during daytime and perhaps the whole night through...
What would you do?

It looks like the title I used is confusing you...

Perhaps, I should have asked : Is there any special method to acclimatize tender foliage to sun?

Anyway, thank you all for your consideration!

 

[TN_Jim]

Since were back on this topic...
As kiwi said...the process of Hardening Off in gardening in general, is moving plants from indoors to outdoors to slowly acclimate the foliage to the sun.

More recently, some people in the bonsai community have used the same terminology to describe the formation of the cuticle on new leaves, when they go from a light green color to a dark green, and become stiffer.

Maybe there should be a better term to use, so people dont get confused....because its confusing...

To throw another wrench into the gears, we have Lignification!
Lignification is the depositing of Lignin in cell walls of a plant to create wood.

Now, leaves are not wood...so can lignification really be used to describe the process of the formation of the cuticle???
I'd have to say no, based on that...
But is lignin also present in the leaves???...this I don't know exactly...

Lignin is in leaves and fruits..like the skin of a grape, it keeps cells from collapsing....and it would be very abundant in the skin of a grape for example, or dermal layers of leaf.

 

[Anthony]

Process is simple.
To learn how - go slowly at your pace.

One hour of morning sun for a week.
2 hours second week
3 hours third week .................

As you gain experience you will know how many hrs.
Good Day
Anthony

 

[my nellie]

At last!
Someone is describing his method!

But what about the clear plastic enclosure?
Should I remove it completely (while still keeping the pot in the shade)?
What is your thought?

Thank you @Anthony

 

[just.wing.it]

Lignin is in leaves and fruits..like the skin of a grape, it keeps cells from collapsing....and it would be very abundant in the skin of a grape for example, or dermal layers of leaf.

Nice, just the info I was hoping for!
So its settled then.

 

[Smoke]

Nice, just the info I was hoping for!
So its settled then.

Settled in your head but not settled with respect to pruning. That was what brought the whole thing up in the first place. Guy wouldn't prune till it hardened off, wasting growing season in the process. Then you come in with this cuticle business, which I thought frankly was something on my fingernail, and upon looking it up, I find it is a hard waxy substance that grows on the leaf surface helping it to reduce transpiration. Wikipedia says nothing about this in regards to pruning a tree. Besides I find the term "cuticle" to be off putting and would prefer to just have my leaves become "mature".

So I ask again what the hell does hardening off have to do with pruning a tree when ever you wish?

 

[Anthony]

@my nellie ,

Αλεξάνδρα,

I am afraid all I can offer is this.

When the hackberries come out of the fridge. They go to an area of
bright light, and no breeze for a week.
May or may not be repotted.
When the buds appear, after a week, they are placed where they get
morning sun [ until 10 a.m ] or dappled sunlight.

We discovered this year that they prefer gentle breezes and dappled
sunlight.
Last year we changed to heavy sun and breeze.
Growth was not as good..
Before that they were on a stand with dappled sunlight and gentle breezes,
but because that was the only space we had.
So what was done early on in ignorance, was better.

Have never had to use plastic anything.

The time for awakening fridge children is from April 1st.
.
Our temperatures will be around 22 deg.C by night
and around or under 33 deg.C [ for less than an hour ]
And dry, no rain. Hunidity around 70 to a low of 45 % as the sun
peaks around 12 noon, humidity going back up for the night.

So we can also control the repotting watering.

With the spring flush for for April [ and a repot ]
no fertiliser.
May - a trim and fertiliser, once a week .
Then June, a trim and fertiliser
Repeat as above until November.

Apart from the spring flush, the other trims are after 10 leaves,
back to one.

If fixing damage, more leaves are allowed.

Not much else to say.
Hope this helps ------- I encourage you to get the Greek Celtis.
Good Day
Anthony

 

[KiwiPlantGuy]

Thank you for your input @just.wing.it !

However, I'm afraid I failed to pass my message through to you people.

What I was aiming at when creating this thread is the method (if any) to gradually/slowly acclimatize the new tender foliage to the sun.
For example, I said above that I intend to open the bag for some hours during daytime and perhaps the whole night through...
What would you do?

It looks like the title I used is confusing you...

Perhaps, I should have asked : Is there any special method to acclimatize tender foliage to sun?

Anyway, thank you all for your consideration!

Hi Alexandra,
My only addition to @Anthony posts is that I would avoid the afternoon sun as may be too strong for sensitive soft leaves. So yes, remove humidity tent, don’t “baby” the tree as it is a tree not a soft indoor plant.
Acclimatization is generally used in comparison to a plant traveling from one zone to another (eg zone 7 to 4) as the zone 7 plants will grow faster in the spring than zone 4 and new growth will get frosted or burnt by cold winds etc.
I just don’t think you are dealing with this, and probably overly concerned/worrying/over-thinking this.
Good luck and keep us posted with new growth pictures.
Charles

 

[just.wing.it]

Settled in your head but not settled with respect to pruning. That was what brought the whole thing up in the first place. Guy wouldn't prune till it hardened off, wasting growing season in the process. Then you come in with this cuticle business, which I thought frankly was something on my fingernail, and upon looking it up, I find it is a hard waxy substance that grows on the leaf surface helping it to reduce transpiration. Wikipedia says nothing about this in regards to pruning a tree. Besides I find the term "cuticle" to be off putting and would prefer to just have my leaves become "mature".

So I ask again what the hell does hardening off have to do with pruning a tree when ever you wish?

What's settled is that Lignification can be used as a term to explain establishment of the cuticle....because apparently lignin does exist in the leaves as well.

My original learning of lignification was that it's the change from green shoot to wood.
For example, a new shoot on a Taxus...the leaves are light green and soft. Then, depending on your climate, they "lignify" in June...but the branch stays green until the next year....then it lignifies and turns woody.

As far as what that means for a tree and why its important....well....
I'd explain it again, but ive already done it too many times.
I feel like you're just being redundant for redundancy's sake, now...

But, here we go....one last time short and sweet, just for you Al, "the health of the tree is always paramount." That's why its important.

As I said before, your growing season is much longer than most of ours, if I pruned my trees consistently before "leaf Lignification" they would never have the time needed to photosynthesize and the tree would get weaker and weaker year after year and eventually give up.

Its about energy positive states of growth and energy deficient states of growth....
There I said it again anyway...

 

[papymandarin]

well actually the cuticle (botanically speaking) is not made of lignin but lipids (there is also some lignins in mature leaves but they don't form the cuticle), however those are also a by product of an active photosynthesis of leaves and a sign the tree is actively producing matter instead of consuming its reserves to push new growth.
That being said, all this debate about hardening off, maturation, lignification ect, is really for me a terminology hair-splitting waste of time, call it whatever you want, just learn to recognize the signs the tree is giving you that it is ready to be trimmed (if it's needed)

 

[just.wing.it]

well actually the cuticle (botanically speaking) is not made of lignin but lipids (there is also some lignins in mature leaves but they don't form the cuticle), however those are also a by product of an active photosynthesis of leaves and a sign the tree is actively producing matter instead of consuming its reserves to push new growth.
That being said, all this debate about hardening off, maturation, lignification ect, is really for me a terminology hair-splitting waste of time, call it whatever you want, just learn to recognize the signs the tree is giving you that it is ready to be trimmed (if it's needed)

Truth.
Thanks.

 

[Smoke]

What's settled is that Lignification can be used as a term to explain establishment of the cuticle....because apparently lignin does exist in the leaves as well.

My original learning of lignification was that it's the change from green shoot to wood.
For example, a new shoot on a Taxus...the leaves are light green and soft. Then, depending on your climate, they "lignify" in June...but the branch stays green until the next year....then it lignifies and turns woody.

As far as what that means for a tree and why its important....well....
I'd explain it again, but ive already done it too many times.
I feel like you're just being redundant for redundancy's sake, now...

But, here we go....one last time short and sweet, just for you Al, "the health of the tree is always paramount." That's why its important.

As I said before, your growing season is much longer than most of ours, if I pruned my trees consistently before "leaf Lignification" they would never have the time needed to photosynthesize and the tree would get weaker and weaker year after year and eventually give up.

Its about energy positive states of growth and energy deficient states of growth....
There I said it again anyway...

Okay, from a purely scientific standpoint that makes sense. But... do you just accept that as fact and live with it or do you work trees to find out if the trees respond or just take some eggheads word for it. I don't and thats why I can develop trees fast and guys around here work on trees for decades and they never develop. I got guys in the club that do the same thing and frankly I find it rather pathetic. If there is one thing I have learned about bonsai is that one must do what works for them and really makes a difference, share it if you like, but it's up to those that read here to apply it to their backyard.

So what do you do, do you wait till all this nonsense takes place or do you get in there and work your trees properly?

 

[just.wing.it]

Okay, from a purely scientific standpoint that makes sense. But... do you just accept that as fact and live with it or do you work trees to find out if the trees respond or just take some eggheads word for it. I don't and thats why I can develop trees fast and guys around here work on trees for decades and they never develop. I got guys in the club that do the same thing and frankly I find it rather pathetic. If there is one thing I have learned about bonsai is that one must do what works for them and really makes a difference, share it if you like, but it's up to those that read here to apply it to their backyard.

So what do you do, do you wait till all this nonsense takes place or do you get in there and work your trees properly?

You should read some of my threads.
As a matter of fact, I have this exact type of experimental work going on right now...mostly with Taxus...but I am trying many others as well.

This year I've done early spring work to one, including barerooting and root reduction (first time after collected from hedgerow, 3 years prior).
I've done late spring work, "before leaves hardened", to one, including creating new dead wood, foliage reduction and wiring.
I've done early summer work to one, (after leaves hardened) including foliage reduction and minor wiring.
I have one that I did a 90+% root reduction on in early spring, to see how it handles that...
And I have another one that I didnt do anything to yet, and will work in late summer, probably Sept.

Believe me, I want to do more with deciduous trees, and ground growing and all of it...but I just got moved into a new house and we're still unpacking...
My commute varies, but usually 2 hours each way....
Got an almost 2 year old running around, bonsai is difficult to have time for right now...
But I do all I can, as far as reading, learning and working on my trees in a way that teaches me things.

Again Al, thanks for your help!

 

[my nellie]

... ...I am afraid all I can offer is this.
... ...Not much else to say.
Hope this helps ------- I encourage you to get the Greek Celtis.

Thank you again for your time!
You did help!
My mind is clearer now.

 

[my nellie]

... ...Acclimatization is generally used in comparison to a plant traveling from one zone to another... ...I just don’t think you are dealing with this, and probably overly concerned/worrying/over-thinking this.
Good luck and keep us posted with new growth pictures.

Hi Charles,
Thank you, too.
No I am not dealing with "acclimatization" in this way, but thank you for the clarification.
You are correct..., I think I am overly babying the tree... but this is because I don't want to risk loosing it...
Moreover, this is the first time in my experience that a tree put into a bag is pushing new growth this late in summer. All my previous experience is with trees which started to sprout in spring, so no problem taking them out of the humid environment.
And I do hope I will have the chance to update this thread

 

[my nellie]

Thank you all the other members for offering scientific views on the debated issues