Post-root pruning root rot

[Anthony]

All plants that come from plant nurseries over here are
bare rooted. For the introduction of the bonsai mix we use.

Nurseries down here use a blend of top soil and fine sand
with a little organic matter.

Works fine for a few years, but evolves into death mix,
especially, when the idea is to purchase and plant in the
ground immediately.

Bare rooting becomes a problem when one keeps making
a clay/sand mix, after the good old farming days.
The clay after x time gums up the soil and starts to kill
the fine roots and the tree starts to produce thick roots.

Then you have to wash out, and it takes x months for
recovery. While you try to cut/wire/ fertilise.
It is kinda pointless practice ------- backward really.
But then who cares, this is a hobby.
Good Day
Anthony

* Love it, long discussion about - Hardening off and one
sensible guy explains it in x lines.
Lignification versus Hardening off.

 

[Lazylightningny]

Thanks everyone for your advice. What's the consensus on summer bare rooting during summer dormancy as opposed to spring?

 

[just.wing.it]

I dont have much experience with summer dormancy root work....I think every tree I've done was in early spring or late winter.

 

[0soyoung]

The consensus will likely be that you cannot repot anything anytime other than in spring 'as buds swell', but maybe these treads will give you some confidence in repotting at other times such as Aug/Sep.

• douglas fir repotting experiment
• lodgepole pine repotting experiment
• cork oak repotting experiment
• zelkova repotting experiment
• eastern redbud repotting experiment.

I also have successfully repotted (meaning at least HBR if not fully bare rooted) all of the following at least once and most habitually, in Aug/Sep:

• viburnum
• rose
• azaleas of various varieties
• junipers of various varieties
• quinces of various varieties
• pyracantha
• cotoneaster of various varieties
• p. nigra
• p. mugo
• p. thunbergii of various varieties
• p. densiflora
• p. densiflora x thunbergii
• p. parviflora (on p. sylvestris and on p. thunbergii roots)
• p. strobus
• p. bungeana
• picea abies
• picea pungens
• abies concolor
• cedrus atlantica
• arborvitae
• tsuga canadensis

I don't know what I have forgotten that should be on this list, but ....

 

[Lazylightningny]

The consensus will likely be that you cannot repot anything anytime other than in spring 'as buds swell', but maybe these treads will give you some confidence in repotting at other times such as Aug/Sep.

• douglas fir repotting experiment
• lodgepole pine repotting experiment
• cork oak repotting experiment
• zelkova repotting experiment
• eastern redbud repotting experiment.

I also have successfully repotted (meaning at least HBR if not fully bare rooted) all of the following at least once and most habitually, in Aug/Sep:

• viburnum
• rose
• azaleas of various varieties
• junipers of various varieties
• quinces of various varieties
• pyracantha
• cotoneaster of various varieties
• p. nigra
• p. mugo
• p. thunbergii of various varieties
• p. densiflora
• p. densiflora x thunbergii
• p. parviflora (on p. sylvestris and on p. thunbergii roots)
• p. strobus
• p. bungeanahi
• picea abies
• picea pungens
• abies concolor
• cedrus atlantica
• arborvitae
• tsuga canadensis

I don't know what I have forgotten that should be on this list, but ....

This is a great resource, but unfortunately, on my computer at least, the tables did not come through, and so I could not read them. What were the dates of repotting? Did you bare root, for the most part? What do you think is the reason that repotting late in the season works as well or better than in spring? The idea behind spring repotting, as I understand it, is that all the energy in the roots has been distrubuted up into stems and buds, and are close to depletion, therefore pruning should not adversely affect it. What about late season repotting? Thanks for the info.

 

[0soyoung]

This is a great resource, but unfortunately, on my computer at least, the tables did not come through, and so I could not read them. What were the dates of repotting? Did you bare root, for the most part? What do you think is the reason that repotting late in the season works as well or better than in spring? The idea behind spring repotting, as I understand it, is that all the energy in the roots has been distrubuted up into stems and buds, and are close to depletion, therefore pruning should not adversely affect it. What about late season repotting? Thanks for the info.

The tables are a site problem - originally they were okay, then the BNut site software changed and the hypertext was no longer handled properly - it is fairly easy (though tedious) to reconstruct the tables if you are familiar with hypertext. If you have MS Excel, you may be able to copy from the site and get Excel to reconstruct the table by simply pasting the clipboard contents into a cell.

The repotting routine for the experiments was full bare root and then pruning the roots back to the edges of the bottom of the pot (i.e., the pot was flipped upside down and the bare rooted tree set atop it for root pruning). This, IMHO, is pretty much equivalent to the normal amount of root pruning we repot trees in bonsai pots (though all the experiment trees were in standard plastic nursery pots). This was done at various dates around the change of month Aug/Sep - I have recorded dates between 14 August and 7 October, even though I do believe the window is as wide as a couple of weeks after the summer solstice (say mid-Jul) to before first frost (late November for me).

I think summer/fall repotting is as good as and maybe better than spring because the plants have newly hardened, highly productive foliage to power root growth (recovery from repotting and root pruning damage). Delicate leafed species such as circis (redbud) and acer palmatum loose much water through their leaf surfaces even when the leaf stomata are closed. Waxy leafed species on the other hand don't, hence they are very capable of restricting water loss to transpiration by closing stomata (the natural response to water stress). Shoot extension happens because cells near the tip are inflated by water - in other words, it takes a lot of water to extend stems and present new foliage. So, it seems straightforward to me that times when shoots are actively extending is a bad time to restict water adsorption by pruning roots.

... in brief.

 

[Lazylightningny]

Makes perfect sense. I will be doing some experimenting myself this season, albeit on a much smaller scale than you. Thanks for all your input.

 

[0soyoung]

Makes perfect sense. I will be doing some experimenting myself this season, albeit on a much smaller scale than you. Thanks for all your input.

I look forward to reading about what you did and what you got as a result.

 

[Lazylightningny]

I look forward to reading about what you did and what you got as a result.

I have two cotoneasters and two firethorns (closely related species, both in family Rosaceae) that are staying heavy in the pot which I will try these on this Aug/Sept. Since this is the time of year that trees are laying on roots rather heavily, I'm assuming that, if healthy, and with enough lignified foliage, the plants will have time to repair any roots damaged in the bare rooting process.

 

[Lazylightningny]

The consensus will likely be that you cannot repot anything anytime other than in spring 'as buds swell', but maybe these treads will give you some confidence in repotting at other times such as Aug/Sep.

• douglas fir repotting experiment
• lodgepole pine repotting experiment
• cork oak repotting experiment
• zelkova repotting experiment
• eastern redbud repotting experiment.

I also have successfully repotted (meaning at least HBR if not fully bare rooted) all of the following at least once and most habitually, in Aug/Sep:

• viburnum
• rose
• azaleas of various varieties
• junipers of various varieties
• quinces of various varieties
• pyracantha
• cotoneaster of various varieties
• p. nigra
• p. mugo
• p. thunbergii of various varieties
• p. densiflora
• p. densiflora x thunbergii
• p. parviflora (on p. sylvestris and on p. thunbergii roots)
• p. strobus
• p. bungeana
• picea abies
• picea pungens
• abies concolor
• cedrus atlantica
• arborvitae
• tsuga canadensis

I don't know what I have forgotten that should be on this list, but ....

Oso, What are your criteria for half bare rooting vs. bare rooting? Is it related to species, or your assessment of the tree's overall health?

 

[0soyoung]

Oso, What are your criteria for half bare rooting vs. bare rooting? Is it related to species, or your assessment of the tree's overall health?

Just trying to say this succinctly:

HBR conifers in organic soil/dirt, otherwise everything can be fully bare rooted

Known exceptions: pinus mugo, pinus strobus, pinus nigra, spruces, firs (in organic 'dirt') can be fully bare rooted between the time of the summer solstice and autumnal equinox (circa August for us northern hemisphere dwellers).​

​

On the other hand, any and everything can be Half Bare Rooted (in spring 'as buds, swell' or after the summer solstice).

 

[R3x]

It was written here but not to the extent I'd expect (at least I didn't catch it). What kind of soil do you use? I would suggest inorganic soil as is the modern bonsai practice. That way you always get enough air for the roots as well good water drainage. I always suggest reading Walter Pall's article on substate, feeding and watering: http://walter-pall-bonsai.blogspot.com/2010/06/feeding-substrate-and-watering-english.html

 

[Lazylightningny]

Just trying to say this succinctly:

HBR conifers in organic soil/dirt

You use garden soil, not inorganic bonsai soil? Or am I reading this incorrectly?

 

[0soyoung]

You use garden soil, not inorganic bonsai soil? Or am I reading this incorrectly?

I buy lots of garden center stuff and also dig things from our landscape that my wife and I no longer want there, but that I think might be interesting as bonsai. These 'starts' are in 'dirt'. I move everything into, my chosen inorganic substrate, Turface MVP.

I have found no apparent need for HBR once all organic soil/'dirt' has been removed and the tree is in nothing but MVP. I use only 'chemical fertilizers' with MBP, usually Osmocote-Plus.

I imagine the use of organic fert and/or Akadama could change this and may account for why many people, such as Adair M, advocate HBR of established bonsai. I am convinced that it isn't because of pumice and/or lava.

 

[Lazylightningny]

I buy lots of garden center stuff and also dig things from our landscape that my wife and I no longer want there, but that I think might be interesting as bonsai. These 'starts' are in 'dirt'. I move everything into, my chosen inorganic substrate, Turface MVP.

I have found no apparent need for HBR once all organic soil/'dirt' has been removed and the tree is in nothing but MVP. I use only 'chemical fertilizers' with MBP, usually Osmocote-Plus.

I imagine the use of organic fert and/or Akadama could change this and may account for why many people, such as Adair M, advocate HBR of established bonsai. I am convinced that it isn't because of pumice and/or lava.

Don't you then have to bare root it again to get it into inorganic substrate?

 

[ysrgrathe]

I think you are misunderstanding -- I read this as he HBR conifers the first time when taking plants from field / potting soil into inorganic.

What's not totally clear is when you say you don't need to HBR once in inorganic, @0soyoung do you mean that you fully bare root conifers in future repottings?

 

[0soyoung]

I think you are misunderstanding -- I read this as he HBR conifers the first time when taking plants from field / potting soil into inorganic.

This is correct.

What's not totally clear is when you say you don't need to HBR once in inorganic, @0soyoung do you mean that you fully bare root conifers in future repottings?

I don't necessarily make a point of bare rooting any of my trees (in Turface) when I repot them. When it is necessary to (re-)establish good root structure, I do. Otherwise, I just remove downward growing roots and an inch or two of the periphery (using a root hook), root prune to those surfaces and back fill with 'fresh'/clean Turface when putting it back into its pot.

Specifically with trees in my repotting experiments (Douglas firs, lodgepole pines, cork oaks, and zelkovas) I did (and continue to) completely bare root them every time they were repotted. I've continued to treat those threes in the same way (full bare root, prune to the periphery of the pot bottom), even when I graduated them to larger pots. Douglas firs that I let run are now close to 5 feet tall in pots no larger than the bottom third of a 5 gallon plastic nursery pot and this full bare root repotting treatment (done in spring or after the summer solstice).

Once in Turface I can do any degree of root exposure I want, from slip potting (roots untouched) to full/complete/total bare rooting.


On the other hand, I see that people who use organic ferts and/or Akadama say one must HBR (conifers) when repotting.

[sigh].

 

[ysrgrathe]

My impression is that Boon doesn't think it impossible to bare root conifers, just not worth the risk, especially on older trees. He has some very nice trees, so I can understand not taking unnecessary risks.

 

[Lazylightningny]

I think you are misunderstanding -- I read this as he HBR conifers the first time when taking plants from field / potting soil into inorganic.

Yep, I read it wrong.