Late summer repotting

Walter Pall

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Spruce # 87

It's called 'late summer repotting' Never ever fall! Summer is until mid-September. But that's already LATE. I have repotted a huge spruce yesterday with Thomas. Now starts the repotting time until first week of September. You have to watch two things. General health of tree. Do not repot a weak tree. Well, And second the long term weather forecast. If heat wave is approaching don't do it. The best forecast is two weeks of rain but rather warm weather. Why so early? Because the tree has more time to establish itself for winter. Ever day counts.

Warning: all this refers to the climate in the south of Germany. Munich, Germany is about 800 miles north of Toronto latitude wise!!! But due to the Gulf stream we have a climate like e.g. mid- to northern Pennsylvania.



Mind you: we have not cut off a single living root nor have we cut off a single little branch. This is very important. it helps the tree to grow immediately and establish a healthy root system in the new pot. This was August 5 and the weather forecast is mild with some moisture within the next two weeks.


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Forsoothe!

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So, you just ~comb~ the roots out a little and provide new growing medium?
 

Walter Pall

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Sure , one ONLY cuts the roots when necessary. On an old collected tree like this it will be necessary after 30 years in training! So on such a tree you avoid any root cutting.When is it necessary? When water and air cannot go through the substrate anymore and when roots have no place to grow to. Forget everything that you were led to believe about this subject when it comes to old (I mean 100 years upwards) trees.
 

Walter Pall

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In this case repotting was necessary for two reasons:T
There was still soil from the original habitat. It was not known before seeing it how much it was and what sort of soil. Anyway, remove this soil as soon as possible.
The plastic container was far too big and heavy and unsightly.
Again: do not style your tree at all before or while repotting. Do not cut off branches which are obviously 'unnecessary' They are very necessary to feed new roots. Cut them after a year or two when the new roots are well established.
 

Brian Van Fleet

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So, in a tiny swath of Europe and NA, if the weather is mild, the tree is strong, and you don’t cut any roots or branches at all, it is possible to change soil only on some trees?

Why risk it, when a proper repotting performed in the spring shouldn’t necessitate a late summer repotting?

Traditionally, it is necessary to trim roots, especially if a good nebari is desired, or when working a tree into a smaller pot.
 

Walter Pall

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Now lets assume that I am reasonably intelligent. And lets take it as fact that I have any one of 365 days of the year to choose to repot a tree. Why would I do it on August 4? The answer can only be that it is the very best day for that tree in my experience. Why would I know better than almost the whole bonsai world?
Well, about 3,000 collected trees went through my hands in Europe and about another minimum 3,000 in other countries.
 

TomB

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So, in a tiny swath of Europe and NA, if the weather is mild, the tree is strong, and you don’t cut any roots or branches at all, it is possible to change soil only on some trees?
Why risk it, when a proper repotting performed in the spring shouldn’t necessitate a late summer repotting?
Traditionally, it is necessary to trim roots, especially if a good nebari is desired, or when working a tree into a smaller pot.
Walter is not the only person in Europe recommending this, for evergreens at least, arguing that late summer may be better than spring.

The material I'm working with is very different, but I've repotted spruce in August too (following advice Walter has published in the past). On a small nursery spruce, in August 2017 I reduced the rootball by over 60% and did a half-bare-root on the rest. In August 2018 I did a half-bare-root on the other half. A year later, the tree is still nice and healthy. Obviously that's not a 100 year old collected tree, and I probably got away with a lot due to its youth and vigour. Would I risk it with better material? I think so.
 
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@TomB I think the primary concern, at least for me, is whether Walter's "Late Summer Repotting" is meant to replace tradition repotting (he often makes it sounds like it should, as you just did), or is it meant to apply only to a very particular sub-set of trees (along the lines of what he says in post #6 above).

It's important to keep in mind that most of the trees that I have seen Walter apply a "Later Summer Repotting" to are trees that were first grown in japan, where the roots were carefully pruned and worked for 60 years before that nebari and root system landed in his hands.

Like the Hedge Pruning method, the Later Summer Repotting procedure is going to require a thorough and well thought-out post that covers all of the questions that can obviously be expected when posting tid-bits here and there on the forum

attached is a deshojo. what happens if i bring this tree to south germany and i start applying late summer repottings, and only repot when the air and water can't get through or when the roots have no place to go? Or should I first send it to japan for 60 years, or plant it in the wild for 100 years, before bringing repotting it in the late summer? this is also bonsai, so one should hesitate to speak for, or with more knowledge than:

the whole bonsai world
the same discussion just keeps happening over and over:


 

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Brian Van Fleet

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Now lets assume that I am reasonably intelligent. And lets take it as fact that I have any one of 365 days of the year to choose to repot a tree. Why would I do it on August 4? The answer can only be that it is the very best day for that tree in my experience. Why would I know better than almost the whole bonsai world?
Well, about 3,000 collected trees went through my hands in Europe and about another minimum 3,000 in other countries.
I did not question your intelligence, rather the exceptionally specific nature of your repot, vs. the established norm of traditional repotting in spring. People listen to you, and the many qualifiers you list are important distinctions that newcomers may overlook: perfect health, perfect weather forecast, no trimming of anything, soil change only. While these specifics are right for you, they’re not right for everyone, by your description. Not everyone is confident enough in their training and experience to challenge this. I am. You’ve done it long enough to defend your position, but “Do you think I dumb enough to risk it?” is not an acceptable response to my inquiring mind. Maybe you found the timing sweet-spot, maybe you’re lucky, maybe what you’re doing isn’t really a beneficial repot that will ultimately lead to an improved root system. So, what do you think is the secret to your success? You said you don’t come here to teach, but to discuss serious things. So let’s discuss it.

6000 trees doesn’t mean everything everywhere. Brussel’s Bonsai likely handles 6000+ trees a year, and their soil sucks everywhere outside their nursery; right for them, wrong for everyone else. Just like repotting a Spruce in August right for you, it’s wrong for me in Alabama: first, the heat would roast the tree; second, I want a good nebari, which requires pruning and arranging roots; and third, if I do the right work in March, I can change the soil, trim and arrange the roots, not risk the health of the tree, and certainly make it a full year so as to not require a “late summer repot” in the future. So this is why I would not be dumb enough to risk it.
 

sorce

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Can anyone arguing the validity that it IS a better (replacement) time than spring, do so with logic beyond what teachers say, or, "its what we do".

Roots grow just the same now as in spring, if not more, as it is between now and fall when everyone will begin to notice slower water percolation, due to an Excessive root growing cycle.

That makes it a better time, moreso than weather.

But if your forecast for august is drought for 2 weeks, than rain for 2weeks....
Pick the appropriate time!

Simple.

Sorce
 
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I repot nursery grown spruce in August. I have even done major root work in August. I'm between CHicago and Milwaukee in the 'Burbs.

I find summer repotting superior than spring repotting for spruce and some pines.
i'm happy to hear this! if anybody, you are definitely the person to thoroughly explain this!

to put my own question briefly, can you basically do as much to the roots of a tree in august as people traditionally do in spring, and does this apply to all of species that people tend to work with?
 

Brian Van Fleet

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can you basically do as much to the roots of a tree in august as people traditionally do in spring, and does this apply to all of species that people tend to work with?
Who are you asking, because on this page alone we have 3 very different answers:
1, if you are in the South of Germany, and the weather is mild, and the tree is healthy, you can change soil, but “...not cut off a single living root nor...a single little branch.”
Warning: all this refers to the climate in the south of Germany. Munich, Germany is about 800 miles north of Toronto latitude wise!!! But due to the Gulf stream we have a climate like e.g. mid- to northern Pennsylvania.
Mind you: we have not cut off a single living root nor have we cut off a single little branch. This is very important. it helps the tree to grow immediately and establish a healthy root system in the new pot. This was August 5 and the weather forecast is mild with some moisture within the next two weeks.
2. If you are in NE Illinois, Leo has done “major root work in August.”
I repot nursery grown spruce in August. I have even done major root work in August. I'm between CHicago and Milwaukee in the 'Burbs.

I find summer repotting superior than spring repotting for spruce and some pines.
3. I don’t risk it here in the South.
it’s wrong for me in Alabama: first, the heat would roast the tree; second, I want a good nebari, which requires pruning and arranging roots; and third, if I do the right work in March, I can change the soil, trim and arrange the roots, not risk the health of the tree, and certainly make it a full year so as to not require a “late summer repot” in the future. So this is why I would not be dumb enough to risk it.
Maybe we are all right. If my tree identifies as midwestern this month, I can repot it here in Bama without any problem!😜
 
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that's exactly how i feel right now @Brian Van Fleet !

every time the topic comes up, things get more confusing instead of clearer! i really enjoy the comfort and risk-free nature of early spring repots. Right now, the information about late summer repotting is full of gaps and looks very disorganized to my mind. All i know for sure about summer repotting is that it's "better" . . . LOL
 

0soyoung

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that's exactly how i feel right now @Brian Van Fleet !

every time the topic comes up, things get more confusing instead of clearer! i really enjoy the comfort and risk-free nature of early spring repots. Right now, the information about late summer repotting is full of gaps and looks very disorganized to my mind. All i know for sure about summer repotting is that it's "better" . . . LOL
Are your fears well or ill founded?
How does one ever know?
 

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