Late summer repotting

Dav4

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I think this graph has some value. It is top of atmosphere, sure. Imagien thre wer no cluds or mist. Then


Sounds right to me. Make sure you get frost free winter storage.
That's always the compromise, though, it would seem. Unfortunately, frost free winters would almost guarantee early bud break and I'd be forced to do even more shuffling of bonsai in mid to late winter and through our last frost date, as I don't have a cold greenhouse at my disposal. I still may perform some re-pots on less valuable trees in September and see how they fare without frost free protection, perhaps heavily mulched on the ground before the soil freezes. We'll see...
 
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0soyoung

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Sounds right to me. Make sure you get frost free winter storage.
IIRC, Walter, your greenhouse collapsed under the weight of snow last year. Damaged your famous Japanese maple, but it didn't die.
Doesn't this make you question the 'frost-free' winter storage mantra?
 

Walter Pall

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IIRC, Walter, your greenhouse collapsed under the weight of snow last year. Damaged your famous Japanese maple, but it didn't die.
Doesn't this make you question the 'frost-free' winter storage mantra?
No it does not question it. With a lot of money money this is easily solved. All my money is in the trees.
I this one thing what Ido for myself and another what I recommend. I will take lots of risks in my garden but I would never recommend this. In sixty years we never had that much snow. How can you plan for this?
 

wireme

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IIRC, Walter, your greenhouse collapsed under the weight of snow last year. Damaged your famous Japanese maple, but it didn't die.
Doesn't this make you question the 'frost-free' winter storage mantra?
I see what you’re getting at Oso. I have had the same thought. If there’s anything I’m skeptical about it is mainly the requirement for frost free following a late summer repot. If the roots had sufficient time to regrow and heal after late summer why should frost free be required on a tree that otherwise wouldn’t need it? Maybe it’s an assumption that hasn’t been fully tested.
 

Dav4

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I see what you’re getting at Oso. I have had the same thought. If there’s anything I’m skeptical about it is mainly the requirement for frost free following a late summer repot. If the roots had sufficient time to regrow and heal after late summer why should frost free be required on a tree that otherwise wouldn’t need it? Maybe it’s an assumption that hasn’t been fully tested.
That's why I'm re thinking my position on the whole subject... but I won't risk my older, more refined trees with a late summer re-pot... yet ;) .
 

LanceMac10

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Pool ain't open in April.....re-potting sounds fun!!

August and the pool is rockin'.....re-potting sounds like sweat-shop work!!

;):D:D:D:D:D:D:D:D:D


...up here, you can definitely kill your material if your too early on a re-pot....just ask my neighbor!!!! Second thought, probably not, he's still pretty sore about rackin' up his best stuff!!!😭
 

Cable

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Unfortunately, frost free winters would almost guarantee early bud break and I'd be forced to do even more shuffling of bonsai in mid to late winter and through our last frost date, as I don't have a cold greenhouse at my disposal.
Really? Why? This is relevant to my interests because I do some overwintering in my root cellar. Consistently 32-40° all winter long and no frost. I didn't have anything push early this spring that I recall but I also only had a handful of plants. So, what role does frost play in extending bud break?
 

Dav4

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Really? Why? This is relevant to my interests because I do some overwintering in my root cellar. Consistently 32-40° all winter long and no frost. I didn't have anything push early this spring that I recall but I also only had a handful of plants. So, what role does frost play in extending bud break?
In my experience, consistent cold but not frost is needed to prevent bud break... read that as temps in the mid 30's F or lower. Anything higher then that for more then a few days after chill requirements have been met and I'll get movement on my Acers for sure. When I wintered trees in MA, on the floor of my unattached garage, the pots would be covered in frozen mulch for 2-3 months straight pretty much year in and year out. They had probably met their chill requirements by mid January, but I doubt yours meet theirs so soon with your relatively mild cold? Anyway, I don't have anywhere to permanently store trees now that can be kept in that sweet spot range of 32-37F that would induce and maintain dormancy without the risk of frozen toes.
 

Forsoothe!

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I see what you’re getting at Oso. I have had the same thought. If there’s anything I’m skeptical about it is mainly the requirement for frost free following a late summer repot. If the roots had sufficient time to regrow and heal after late summer why should frost free be required on a tree that otherwise wouldn’t need it? Maybe it’s an assumption that hasn’t been fully tested.
There's a difference between grown enough to survive winter and entirely regrown. Again, all factors are on a sliding scale and each individual has to adapt these concepts to their own situation.
 

just.wing.it

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We need a SIMPLE way to understand who can repot when
Maybe the best answer is simply Trial and Error.....until Repeatable Success.

For me, as a relative newb.....only my 5th year attempting to create bonsai, in the Mid-Atlantic region, I have had success repotting in summer and spring both.

I think I need a solid decade at least, to make a certain determination on what works for what tree and when.

I think there are more things at play with summer repotting than spring.....maybe more dangers depending, on......so many things.

I will say that it seems like Junipers and Mugos are OK with mid summer root work....to some extent.
 

JefeW

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I’m new to bonsai but not to deciduous horticulture. The spring repot is new to me, but makes sense because you won’t kill the tree with a hard winter coming up, you get a full cycle of growth. In the tiny pots, it seems logical that frost is enemy number one. What I have trouble with for deciduous is how spring repotting doesn’t set your tree back significantly. You have no canopy, then you significantly damage the roots, so the tree must grow both. Maybe everything is a trade off doing the bonsai?
 
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Any chance you could start a separate thread on your hemlock? I’m always searching for experience/advice.

And, props to everyone for getting the thread back on topic. There are some great insights here.
Sorry man, I have 2 eastern hemlocks one collected last summer doing well in its box and the one in the picture from nursery stock. I don't really have any experience yet with hemlocks. All I know is that in the forests here they often are an understory tree in the shade of larger ones and in particular under the shade of all the deciduous for most of its first years until it breaks through in height. I don't know how this affects its growth. I can only speculate that it must have rapid growth spurs while young in the spring while the deciduous around it didn't fully cover the sun. It doesn't mean though that it cannot or should not grow in full sun. My collected Tsuga was left in shade similar to where it was collected the reminder of its first year but this year it has been in full sun without any issues.
 

JudyB

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What I have trouble with for deciduous is how spring repotting doesn’t set your tree back significantly. You have no canopy, then you significantly damage the roots, so the tree must grow both.
Basically the roots store the energy for the tree over the winter. When the tree starts to break dormancy all that energy is transferred out of the roots and up into the canopy. Then the new leaves start the process of converting sunlight to food, and the tree is able to grow new roots. At least that is my simplistic understanding of how energy is stored in deciduous trees.
 

Colorado

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Basically the roots store the energy for the tree over the winter. When the tree starts to break dormancy all that energy is transferred out of the roots and up into the canopy. Then the new leaves start the process of converting sunlight to food, and the tree is able to grow new roots. At least that is my simplistic understanding of how energy is stored in deciduous trees.
This is what I don’t get either...I have the same understanding, Judy. I’ve seen it described as the roots “store energy” over the winter and then “send” the energy up the tree, to the buds, in spring.

So if the roots store all the energy, wouldn’t doing a significant root reduction in spring rob the tree of most of its “stored energy?”

Honest question here - just trying to wrap my head around all this.
 

JudyB

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This is what I don’t get either...I have the same understanding, Judy. I’ve seen it described as the roots “store energy” over the winter and then “send” the energy up the tree, to the buds, in spring.

So if the roots store all the energy, wouldn’t doing a significant root reduction in spring rob the tree of most of its “stored energy?”

Honest question here - just trying to wrap my head around all this.
I think by the time we notice the tree "moving" the stored energy has made it's way up into the top of the tree, and that is what we are seeing when the buds swell and open.
 

Cable

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I’m new to bonsai but not to deciduous horticulture. The spring repot is new to me, but makes sense because you won’t kill the tree with a hard winter coming up, you get a full cycle of growth. In the tiny pots, it seems logical that frost is enemy number one. What I have trouble with for deciduous is how spring repotting doesn’t set your tree back significantly. You have no canopy, then you significantly damage the roots, so the tree must grow both. Maybe everything is a trade off doing the bonsai?
In most deciduous trees energy is stored in the entire vascular system, not just in the roots. Roots, trunk, branches, buds, all have stored energy.

This is not only why you can completely bare root and cut off most of the roots and they’ll regrow (on a healthy tree) but also why sometimes the root system dies yet the tree still blooms or leafs out. We refer to that as a tree that “is dead but doesn’t know it yet”.
 
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Forsoothe!

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Think of the energy stored in the vascular system as concentrated sap, or sap high in solids with very little water as the vehicle. In late summer and autumn, sap surplus to the needs of the plant to grow buds for next year stays in the roots and is used to grow roots. As less and less transpiration occurs, the sap in the upper vascular system "parks" where it is and becomes more concentrated as modest transpiration through the bark reduces the % of water in the sap. The drier it becomes, the less damage-prone the upper plant is from freezing air. The dry parts of trees regularly take whatever low temperatures come with the zones they are native to while the root zones acclimated to the same zones are not subjected to lows anywhere near what the air temperature are. The more water normally stored in the root zones, the less able to withstand low temperatures, especially freezing. Many trees that can stand 20 or even 10 or 0°F will be damaged or die from root zones at 20°F. Air temperatures change quickly, but the ground is a poor conductor and temperatures change slowly, especially dry soil. A dry autumn is gardener-friendly. Snow cover is also a poor conductor and insulates land from deep cold, if and only if, the ground has not frozen deeply before the snow covers it. A dry autumn and early and continuous snow cover are gardener-friendly. A wet autumn followed by poor snow cover and extra-low air temperatures will freeze the soil deeper and would be bad for trees like Japanese Maples and others with fleshy, shallow roots. SPF (Spruce-Pine-Fir) have fibrous roots that are not fleshy and will stand much lower temperatures. SPF do not have to re-foliate completely every spring and the needle's waxy coating reduces water loss, so along with the thick sap uses and stores less water. You can tell when you're getting close to the treeline anywhere, -all the trees are needle trees.

So, the energy for plants is stored in sap, some watery in warm climates, some thicker in temperate zones. Concentrated at the ends of growing seasons, in spring, just add water.
 

kouyou

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in light of the last few posts in this thread, there is valuable and reliable discussion about energy storage and management with regards to the seasons in question in these two videos


 

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