Late summer repotting

Maloghurst

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That's not true, roots will continue to grow in the winter as long as the soil isn't frozen.
Only took 30 seconds to research this but here's one: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=20&ved=2ahUKEwjaxPnL6frjAhVSbc0KHWPUCmMQFjATegQICRAC&url=http://arnoldia.arboretum.harvard.edu/pdf/articles/1989-49-4-tree-roots-facts-and-fallacies.pdf&usg=AOvVaw3pAK1jX5_VOCaqpFpCTq8a

"By repeatedly digging up, measuring, and then reburying them, researchers have observed that roots can grow throughout the winter—whenever soil temperatures are above 5 degrees C (40 F) (Hammerle, 1901; Crider, 1928; Ladefoged, 1939)."

I learned it because my old house had issues with tree roots blocking my sewer lines and usually they had to be cleaned out during the winter.
This is a far cry from your first statement of “roots WILL continue to grow as long as the ground is not frozen” if you are repeatedly damaging roots of a tree then this study shows that a tree CAN grow roots even in a state of dormancy. Although 40f is a ways from frozen as well. The ground will not even begin to freeze until temps are 32 f for a period of time.
Most studies show that trees do not grow roots while dormant in winter. Including the one you posted and others I’ve read.
 

wireme

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I can lead a horse to water but I can't make him drink. ¯\_(ツ)_/¯
I met some students once who dug a big hole in the forest up in the Alps somewhere and lined it with plexiglass. Then cover the hole with a tarp. They went down on a regular basis throughout the year and traced the roots with colour codes according to dates. They gave a presentation and had the plexiglass with them at this conference I was at. Pretty cool, yeah some root growth basically all year, a fair bit over winter with 5’ of snow above but the soil not frozen. I really don’t remember any detail of when the main growth activities were.
 
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Maloghurst

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I can lead a horse to water but I can't make him drink. ¯\_(ツ)_/¯
All I’m saying is there are many more studies showing a dormant period of root growth through winter. So you just saying “not true” to that doesn’t seem to serve any purpose to me.
There are many exceptions to the rules. My trees started budding last January when the temps hit 70 F then went back into dormancy. That could also prove that roots were growing too then stopped again. But there is still a dormant period in my trees in winter, even when not frozen.
 

Forsoothe!

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Everything about growing things and climate and local conditions of the whole planet, all "facts" are plastic on a sliding scale and each of us scattered all over the place needs to filter it for what we can, for our purposes, where we are. I'm getting tired of the nitpicking. If someone in Alaska says "X" and someone in Bali says, "not true because in my backyard...", that's a waste of time. The other 5 billion people don't need to hear an argument why, if it is isn't so in Bali it can't be true elsewhere, or why it is in Alaska, it's not necessarily germane elsewhere. We all are offering what we think is important to consider in hopes of helping others and having them reciprocate. I think we're trying to build a model of generalities that each of us can pluck something useful from. Firstly, we need data. OK, so we have a lot more anecdotal than scientific, but we can work with what we have.
 

sorce

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sliding scale and each of us scattered all over the place needs to filter it for what we can, for our purposes, where we are. I'm getting tired of the nitpicking. If someone in Alaska says "X" and someone in Bali says, "not true because in my backyard...", that's a waste of time. The other 5 billion people don't need to hear an argument why, if it is isn't so in Bali it can't be true elsewhere, or why it is in Alaska, it's not necessarily germane elsewhere. We all are offering what we think is important to consider in hopes of helping others

This is why I believe, as generated by this thread, that we should consider the Summer Solstice as a beginning point where we are all (hemisphere particular) even.

Growing season's may start earlier or later, and extend earlier and later, but our middle remains the solstice as far as timing.

Then we can use points to 100 in both directions with point values being the same across maps.

My -36 (late April to May?) Is the same as Alabam's -36, (late March-early April?)
Wireme's -36 (late may early June?)

Same.

Leaf fall is 100 points.

Repot x points before 100 for safety.
I believe the trees know where they are and will "winter-up" accordingly. For this...maybe one week max differential.

Sorce
 

Saddler

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This is why I believe, as generated by this thread, that we should consider the Summer Solstice as a beginning point where we are all (hemisphere particular) even.

Growing season's may start earlier or later, and extend earlier and later, but our middle remains the solstice as far as timing.

Then we can use points to 100 in both directions with point values being the same across maps.

My -36 (late April to May?) Is the same as Alabam's -36, (late March-early April?)
Wireme's -36 (late may early June?)

Same.

Leaf fall is 100 points.

Repot x points before 100 for safety.
I believe the trees know where they are and will "winter-up" accordingly. For this...maybe one week max differential.

Sorce
Except that doesn’t always work. In the Yukon where I used to live, the growing season doesn’t start until very late. In Whitehorse the last spring frost is June 12.
 

Cable

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I met some students once who dug a big hole in the forest up in the Alps somewhere and lined it with plexiglass. Then cover the hole with a tarp. They went down on a regular basis throughout the year and traced the roots with colour codes according to dates. They gave a presentation and had the plexiglass with them at this conference I was at. Pretty cool, yeah some root growth basically all year, a fair bit over winter with 5’ of snow above but the soil not frozen. I really don’t remember any detail of when the main growth activities were.
Nope, that couldn't have happened. Apparently they just made it up... :rolleyes:
 

wireme

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Like the Austrian Rhizoboxes by than a bit larger? Cool
Maybe the same? It was a while ago, international erosion control bioengineering conference. The may have been Austrian and they did call it rhizo-somethingorother, I don’t remember. Mostly I just remember beIng surprised at the growth of conifer roots over winter in the mountains, at the time I thought there wouldn’t be much happening. My own trees stay frozen solid for many months here being shallowly mulched but I imagine folks in warmer places get root growth over winter in pots.
 
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Maybe the same? It was a while ago, international erosion control bioengineering conference. The may have been Austrian and they did call it rhizo-somethingorother, I don’t remember. Mostly I just remember beIng surprised at the growth of conifer roots over winter in the mountains, at the time I thought there wouldn’t be much happening. My own trees stay frozen solid for many months here being shallowly mulched but I imagine folks in warmer places get root growth over winter in pots.
I'm going to retire somewhere south with a longer growing season. New York is bad enough, I can't imagine having just a few good months of growing.
 

sorce

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Except that doesn’t always work. In the Yukon where I used to live, the growing season doesn’t start until very late. In Whitehorse the last spring frost is June 12.
We would have to make it work.
9 days till the solstice.

100/9=11.11 points per day.

Our lingo would involve these points per day.....

Accidental post dispatch..... more.

Sorce
 

Forsoothe!

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Snow, especially deep snow is an insulator against the deep cold air. When and where heavy snow blankets land (mostly mountainsides) before the earth freezes, or freezes deeply, it can take a long time for deeply cold air to cool the snow which can then cool the earth. The Air Force used to teach airmen to dig a hole in deep snow for protection against deep cold air if they had to bail out of their plane in the mountains. Snow is basically ~32°F and transfers heat/cold poorly, changing slowly.
 

wireme

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Snow, especially deep snow is an insulator against the deep cold air. When and where heavy snow blankets land (mostly mountainsides) before the earth freezes, or freezes deeply, it can take a long time for deeply cold air to cool the snow which can then cool the earth. The Air Force used to teach airmen to dig a hole in deep snow for protection against deep cold air if they had to bail out of their plane in the mountains. Snow is basically ~32°F and transfers heat/cold poorly, changing slowly.
This was my home for a month at 4200m in the Himalayas one time...
C14FF10B-445E-4172-92B1-71C2CA0285CA.jpeg

Not gonna say I never got cold but still alive!
 

sorce

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Damn...so yeah....of winter roots and snow.

Had this notion that time or temp doesn't matter.
And it may not.

If a tree must (after fall repot) it'll probly grow roots straight through the winter if well snow covered.

@Smoke how's that hot potted tree?

Sorce
 

Maloghurst

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Damn...so yeah....of winter roots and snow.

Had this notion that time or temp doesn't matter.
And it may not.

If a tree must (after fall repot) it'll probly grow roots straight through the winter if well snow covered.

@Smoke how's that hot potted tree?

Sorce
I’m actually really liking this discussion (most of the time). And your thoughts are accurate for a mild repotting such as was done in the original post. Seems like its actually better if lightly repotting in fall so in spring it can hit the ground running!
I will definitely do it with some of mine.
But time and temp does matter for root growth.
Roots, like shoots, grow most rapidly when temperatures are moderate-between 20 and
30 degrees C (68 and 85 F) (Russell, 1977). So I ask would you do Major root work on a maple in fall? Where you reduce 70% of a root mass? You can do this in spring with a high degree of success because maximum root growth for maples is late spring early summer.
 

M. Frary

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And thru the summer if not too hot.

If there are "periods", it's every moon.

I would love to see the natural conditions in which these said root growth "periods" are observed.🤔

Sounds completely made up at best.

Trees are more opportunistic than stupid.

Sorce
My trees start growing in spring and dont let up until the leaves fall off.
Roots and foliage.
No "flushes"
Just grow.
It's a touch cooler up here and the season is short.
The trees know this and make hay while they can.
 
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Forsoothe!

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Three principles for me are: the tree has to have enough growing time left in the season of major work to recover before quiescence, and, don't work on top and bottom in the same season, and the tree needs all the resources it can to recover, so I don't work the roots if defoliated, and I want the whole canopy to be healthy, mature and present when I do major root reduction. Mid to late June is my first choice to do all these things, with July second best, and early August third choice.

I don't like autumn for root work, maybe because I have had poor results. Trees go to sleep and never wake up. I don't like early spring because removing roots just when the canopy needs the resources of the roots to inflate a whole bunch of leaves doesn't make sense to me.
 

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