Scots pine ....summer repot.....yes or no?

[Colorado]

There has been no rhyme or reason yet at all to repotting times.

There is plenty of rhyme and reason! The reason people repot in spring is because the tree has stored energy (i.e. in an energy positive state). If you repot when the buds are swelling/opening, the spring momentum is already in full force and you’re almost guaranteed that the tree is going to put out new foliage, which is going to power regenerative root growth.

 

[sorce]

There is plenty of rhyme and reason! The reason people repot in spring is because the tree has stored energy (i.e. in an energy positive state). If you repot when the buds are swelling/opening, the spring momentum is already in full force and you’re almost guaranteed that the tree is going to put out new foliage, which is going to power regenerative root growth.

Not rhyme or reason to when...

Rhyme or reason to why they die.

I personally, think it's foolish to tax the roots and the folaige at the same time.

Just because people have been repotting in spring forever, doesn't make it the optimal time.

This falls into that very bonsai non bonsai topic I was talking about in that thread that was moved because some people don't understand how it relates to trees.

If we don't see harm, we won't change our ways.

I'm out to show the harm.

Sorce

 

[Adair M]

0soyoung can go into the extract chemistry involved, but the general understanding that I have is that growing foliage tip produce a chemicals, auxin, which is a hormone that signals to the roots that the top is growing, and that stimulates root growth.

So, the reason spring is a good time to repot is new growth starts. This causes auxin to be produced. The auxin stimulates root growth.

Ergo, spring is a good time to repot because the tree will be stimulated to grow roots.

Individual species may vary, but I have found that this general principle works for the species that I grow.

Some exceptions that I am aware of: tropicals, and olives.

tropicals and olives repot well when they are actively growing, which is summer. Applying the “auxin” theory, I guess that’s when they are producing the most auxin. (I’m no botanist, I’m just speculating.) And, I don’t do tropicals, but that’s when I hear that the guys that grow them repot them. I have had success repotting olives in the spring, and during the summer.

 

[Kadebe]

This thread makes me wonder if there is a resource that shows what work can be done on a particular type of tree at what time and in what zone? If none exists, could we crowd source something like that?

I'm into bonsai... euuh.. (collecting plants in a pot and try to create prebonsai) for 3 months now. I've read many...many threads, books, and viewed a lot of vids.
In the beginning, and even now, I find it bizarre that many people mainly look at the USDA zone. According to the wiki I've read, these zones are mainly classified according to the min and max temperatures. In my humble opinion, this is only a very limited indication. It doesn't take into account humidity, type of wind and many other factors. I live on the outskirts of a town, 2 miles further I'm in an agricultural area, and 10 miles to the other side we have a small forest. These are 3 locations with different conditions, so different impacts on the trees.
Again, that's my opinion as a layman

 

[Leo in N E Illinois]

Sorry Sorce,
I think your emphasis is not on the correct variables.

A table could be built if you used "biomarkers" or "biological set points". For example, IPM schemes use growing degree days, with experimentally determine base temperatures to time when certain pests will be susceptible to a spray application.

Example of Growing Degree Day Mapping

Growing Degree-Days (50) - MSU - Enviroweather

This map shows estimated degree days, base 50F (DD50) for the region.

enviroweather.msu.edu

Example of using GDD set points or biomarkers to time a spray program.

MSU - Enviroweather

Building Enviroweather

enviroweather.msu.edu

By the way every USA state with significant agriculture has websites similar to the ones I linked.

For repotting, a "schedule" could be created based on the number of growing degree days. First experimental data would need to be collected as to what GDD and what base temp is a useful marker for when root growth becomes active. Then across the world, all you would have to know is your GDD accumulation at your location, when you hit the ideal bracket, you can then begin repotting.

Shy of using an environmental cue based program, you can not make a "chart" that will be relevant to anyone in a climate more than a few degrees latitude different than the author's immediate location.

 

[leatherback]

Did your ponderosa make it?

growing as we speak

 

[Leo in N E Illinois]

For example, I know from experience (anecdote not experimental data) that spruce "wake up" and start growing at a significantly earlier point in spring than my JBP. And my P. sylvestris wakes up between the two. My suspicion is that we could accurately predict initial root growth for spruce with a GDD base 40F model, and JBP might require a GDD base 60F, and P sylvestris might be a GDD base 50 model.

It would be difficult to develop the data needed to create these models, but it could be done. Since just about every USA State Ag Extension service maintains GDD maps, all we need is to observe when we see flushes of new growth, and record the GDD at various base temperatures. Once enough data is accumulated, someone could "crunch" the numbers and determine which degree base temp is the one to use and the bracket of GDD for repotting.

As you can see from my outline, this would require a battalion of contributors, to do the data collection. The large amount of data needed means it most likely won't happen. Hell I'm having a hard time making time for a much smaller project, apologies DSD.

 

[leatherback]

all we need is to observe when we see flushes of new growth,

But this would mean liftng the tree from the container multiple times. Unless you mean topgrowth, where I am not convinced that top growth means rootgrowth..

 

[Adair M]

But this would mean liftng the tree from the container multiple times. Unless you mean topgrowth, where I am not convinced that top growth means rootgrowth..

That’s another, “it depends”. Variables like that could vary with the species of tree. Or, how much top growth does it take to create the auxin flow?

 

[leatherback]

That’s another, “it depends”. Variables like that could vary with the species of tree. Or, how much top growth does it take to create the auxin flow?

exactly.

I have found treeroots growing in mid-winter, when temps were around freezing. And I have found plants growing a season without a real development of roots. There are so many variables involved that I doubt any general answers can be formulated. In the end, experience is what pays

 

[Mike Corazzi]

Another way is to dig a ...scoop... of the soil surface and see what it looks like without lifting or removing.
It can be filled back in pretty easily.

 

[sorce]

correct variables

The variables I'm talking about are the very real ones including percentage of folaige mass, amount of time that folaige mass is left on to provide energy, and the energy use afterwards.

Unscientifically speaking.... scissors handsy.

That's the simplest variable we never account for, which leads to true stories of successes and failures, in every season, with every type of material, repotting or collecting, by Newbs and Vets alike.

That is what lacks rhyme and reason. These are true stories strewn about here and elsewhere, I'm not making it up.

I see this study on root growth in spring, but what of the other seasons? It's the other seasons facts I'm interested in, not reinforcement of belief that spring is the best time to Repot.

I am not convinced that top growth means rootgrowth..

It certainly doesn't, since we see roots continue to grow after the leaves fall.

If it's the Auxin in the growing tips during the waxing moon, it makes sense it travels back down with the waning moon.

It is obviously not instantaneous.

All that is left is to see the pattern then.

I don't see much difference on the pattern straight across the seasons. Except for outside of early spring, cold is no longer a factor. Summer may be impossible some places. Then fall brings is back into this sweet spot Walter talks about, when the weather is getting more favorable for growth.

FTR.
Should should definitely not be repotting this tree in summer where you are.

Sorce

 

[Paradox]

I have had the best success where I live with repotting scots pines in the spring.
All of my spring repots survived. I had a couple summer repots die.

I have repotted mugos in both spring and summer with success but my spring repots seem to recover faster and do better than the summer repots

 

[BonjourBonsai]

A table could be built if you used "biomarkers" or "biological set points"

Leo, you are totally right. It is the tree that says when it is ready, not the calendar.

I found this very interesting:

https://phenology.osu.edu/phenology%20very%20short%202011.pdf

Also, this listing of phenological events based on GDDs.

GDD - Calendar

www.oardc.ohio-state.edu

So, if it takes 34 GDD for Acer saccharinum to have its first bloom in Ohio, the same would be true anywhere, regardless of USDA zone, as long as that geographic location supported Acer saccharinum. That's why spring always seems to start later the further north you go away from the equator.

So what about a bonsai calendar based on GDDs? Each bonsai nut could record their own GDDs and use that AS A GUIDE (not absolute rule) to finding the optimal time to do x, where x = root prune, pruning, wiring, defoliating, etc. It would be one more data point, but one that would be more accurate, I believe.

The survey could be as simple as "For Mugos, on what date did you successfully repot, prune, wire, decandle and what were the GDDs on those dates in yur location?

Amazing stuff!

 

[Mike Corazzi]

[QUOTE="Adair M, post:]
That famous German artist who repots mature maple bonsai during the summer doesn’t live where you do!

where YOU live, Mike, is marginal for Scots pine, period. Then trying something Unconventional???

Stick with the methods that have been proven by many who have come before you.
[/QUOTE]

That is proving quite evident.
This heat wave has toasted some of the tops of some of the pads.
Some brown needles (brown all the way) but they do NOT pull off or out.
But it's obvious it is not happy in this heat.

So.... it is now UNDER the bench on an inverted milk carton with only ..bands... of sunlight hitting it.
I "think" that might do it. Time will tell.

It is going to live there for the rest of this "summer" and when (or if) the temps max out to high 70s or 80s later, I'll put it in the sun for the winter.
Whatever "winter" is.

 

[Kadebe]

Leo, you are totally right. It is the tree that says when it is ready, not the calendar.

So, if it takes 34 GDD for Acer saccharinum to have its first bloom in Ohio, the same would be true anywhere, regardless of USDA zone, as long as that geographic location supported Acer saccharinum. That's why spring always seems to start later the further north you go away from the equator.

So what about a bonsai calendar based on GDDs? Each bonsai nut could record their own GDDs and use that AS A GUIDE (not absolute rule) to finding the optimal time to do x, where x = root prune, pruning, wiring, defoliating, etc. It would be one more data point, but one that would be more accurate, I believe.

The survey could be as simple as "For Mugos, on what date did you successfully repot, prune, wire, decandle and what were the GDDs on those dates in yur location?

Amazing stuff!

Theory is all well and good, but in recent years it happens more and more , that a warmer period at the beginning of the year opened the buds, but then the weather changed...a few weeks of cold weather. Then your GDD is useless. Because of this in the past years, farmers have already lost a large part of their harvest several times. In my opinion, solely relying on GDD can set your tree back... or worse

 

[Adair M]

[QUOTE="Adair M, post:]
That famous German artist who repots mature maple bonsai during the summer doesn’t live where you do!

where YOU live, Mike, is marginal for Scots pine, period. Then trying something Unconventional???

Stick with the methods that have been proven by many who have come before you.

That is proving quite evident.
This heat wave has toasted some of the tops of some of the pads.
Some brown needles (brown all the way) but they do NOT pull off or out.
But it's obvious it is not happy in this heat.

So.... it is now UNDER the bench on an inverted milk carton with only ..bands... of sunlight hitting it.
I "think" that might do it. Time will tell.

It is going to live there for the rest of this "summer" and when (or if) the temps max out to high 70s or 80s later, I'll put it in the sun for the winter.
Whatever "winter" is.
[/QUOTE]
Mike, I suggest you try California Juniper and Valley Oaks. You know, the things that live where you do?

Japanese Black Pines like the heat.

I’ve said it before, and I’m sure I will again: One of the keys to becoming successful with bonsai is to choose species that thrive in your environment, or in an environment you are able to provide for them.

 

[casun]

I’m trying to understand reason why some say to not repot pines in the summer. Generally speaking, is it because the summer heat plus the repot shock is too much stress? Or is it because as we move into fall/winter and days get shorter and cooler the tree won’t be able to generate enough new roots?

If I live in an area with very mild winters, with temperatures never reaching freezing, is it safe to repot in late August?

 

[Paradox]

I’m trying to understand reason why some say to not repot pines in the summer. Generally speaking, is it because the summer heat plus the repot shock is too much stress? Or is it because as we move into fall/winter and days get shorter and cooler the tree won’t be able to generate enough new roots?

If I live in an area with very mild winters, with temperatures never reaching freezing, is it safe to repot in late August?

Both. When you do a repot, the roots get compromised. The roots is the main source of water to the rest of the tree.
In the summer, transpiration (loss of water) is greater because of the heat. If the roots have diminished capacity to take up water because they are reduced and or healing, the tree could die.

Your second point is also true with regard to timing and new root growth vs the onset of winter.

You live in southern California, which indicates that August could be quite hot and dry. IMO repotting in prolonged 100+ degree weather is very risky to the tree.

 

[Mike Corazzi]

Oh, I have a shitpot of junipers, JBP, olives, cotoneaster, and elm. Even an oak that throws 1-3 inches of new green EVERY day.

I wouldn't fret over this Scots except that I've had it so long and it had such a hard start.
It has managed to live 20+ years even if not ecstatic about it.