Growing a thick root mass
- Thread starter Lazylightningny
- Start date
0soyoung
Imperial Masterpiece
One tree versus another doesn't have much significance. One cannot demonstrate in any way that anything was not the result of chance. Chance that you happened to pick the most bud laden tree for the pond basket, etc., etc.
Johnathan
Omono
Can we go all the way back to the beginning?....... What is "air pruning" and "mechanical pruning"?
It's Kev
Omono
A penny drops... so it’s like pond baskets then.
And thanks, I never left though, I was just lurking in the shadows because I had nothing to post due to my recent traumatic failure
Air pruning (and using proper media) are both important tools. I grow all my pines in colanders. We still need to prune the roots though. It is not a one or other thing. You will get the best results if you use all of the appropriate techniques.
Saddler
Chumono
Air pruning is when the roots hit air and the tip dies. Mechanical pruning is using scissors to cut the root.
markyscott
Imperial Masterpiece
So the nursery industry has this problem when nurserymen cultivate container grow trees. The roots hit the pot wall and encircle the container. As the tree grows, they up pot and over time you end up with a mass of encircling roots. If the roots are too encircled and wadded up in the container, when they sell it and it is planted, the roots will never spread away from the trunk. You won’t get the nice basal flare on the tree and it can remain unstable. Such trees are unsuitable for the nursery trade and they are culled before sale. They look like this:
So a long time ago people started experimenting with techniques that they could use to decrease the number of trees that are culled. They experimented with shaving the rootball and using ribbed containers and other techniques. One of them was air pots. They’re just regular nursery cans with holes in the side. The idea was that the roots will grow until they hit the container walls and then die because they get desiccated quickly. They called it air pruning. No encircling roots, then you’ll have lower cull rates, right? Well - it is right. You can find dozens and dozens of academic papers researching air pots. How roots grow with different hole patterns. How roots grow with different shapes of holes. How cull rates change with different types of air pots. The list goes on and on. They really do prevent encircling roots.
So why don’t you see all nursery trees grown in air pots? The reason is because there is a trade off. First, air pots are more expensive than regular pots. Quite a bit more expensive in fact. Second, because trees grow more SLOWLY in air pots. So there’s a cost. And it’s just cheaper to cull.
S
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markyscott
Imperial Masterpiece
And before the flaming arrows come, I’m sure you’ll see folks post one or two tree anecdotes in an attempt to prove that trees actually grow faster in air pots. But in fact, when roots are constantly dying off, there’s a cost in growth rates. And the same folks who did all the air pot experiments on tens of thousands of trees demonstrated that trees grow more slowly in air pots than in regular pots.
Here’s one reference.
http://hort.ifas.ufl.edu/woody/documents/articles/EFG0901.pdf
The objective of the study was to evaluate the described shaving technique as a means of avoiding encircling roots on nursery grown plants. The primary issue that they were addressing was stability of nursery trees in the landscape - apparently trees with roots issuing radially from the trunk are more stable than trees with encircling roots. Control was provided by trees up-potted without anything having been done to the rootball - they reported that growth was not affected by shaving vs control. The results were measured by a qualitative evaluation of the rootball and the degree to which encircling roots were eliminated by the shaving, not by growth rates. There was no quantitative comparison of growth rates following the shaving technique to any other root pruning technique used by nurserymen (let alone bonsai growers). However, they did offer a very interesting but qualified (and qualitative) comparison to other studies which did look at growth rates:
"This demonstrates as others have shown (15) that container grown shade trees receiving regular irrigation can recover from severe root pruning without slowing their shoot growth."
The authors also referenced in the paper to "air pruning". Their characterization of air pruning was the following:
"Seedlings in air-pruning 5 cm (2 in) diameter containers had less packed roots, less spiraling roots, and fewer L-shaped roots (25). The authors noted that seedling grown trees in air-pruning containers produced less root defects than those grown in solid-walled containers, but they had slower root and canopy growth in the nursery due to the lateral air- pruning (25)."
So mechanical root pruning doesn’t affect top growth, but air pruning does.
S
Here’s one reference.
http://hort.ifas.ufl.edu/woody/documents/articles/EFG0901.pdf
The objective of the study was to evaluate the described shaving technique as a means of avoiding encircling roots on nursery grown plants. The primary issue that they were addressing was stability of nursery trees in the landscape - apparently trees with roots issuing radially from the trunk are more stable than trees with encircling roots. Control was provided by trees up-potted without anything having been done to the rootball - they reported that growth was not affected by shaving vs control. The results were measured by a qualitative evaluation of the rootball and the degree to which encircling roots were eliminated by the shaving, not by growth rates. There was no quantitative comparison of growth rates following the shaving technique to any other root pruning technique used by nurserymen (let alone bonsai growers). However, they did offer a very interesting but qualified (and qualitative) comparison to other studies which did look at growth rates:
"This demonstrates as others have shown (15) that container grown shade trees receiving regular irrigation can recover from severe root pruning without slowing their shoot growth."
The authors also referenced in the paper to "air pruning". Their characterization of air pruning was the following:
"Seedlings in air-pruning 5 cm (2 in) diameter containers had less packed roots, less spiraling roots, and fewer L-shaped roots (25). The authors noted that seedling grown trees in air-pruning containers produced less root defects than those grown in solid-walled containers, but they had slower root and canopy growth in the nursery due to the lateral air- pruning (25)."
So mechanical root pruning doesn’t affect top growth, but air pruning does.
S
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markyscott
Imperial Masterpiece
So when to use air pots or colanders? I use them for pines because those tend to grow a long time between reports an I don’t want encircling roots. I repot hardwoods and the like frequently, so no problem with encircling roots on those. Basically I use them for any plant in development for whic I intend to wait a long time between repots.
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Saddler
Chumono
That’s very interesting and falls inline with my airpruning experiences. I had a bunch of trees die because it got so hot and I wasn’t able to water them that night due to circumstances beyond my control, but the rest never grew as well as the ones in growboxes. Now that I have had a good experience with Anderson flats, I have been considering trying colanders again. The information you posted has me thinking I should be spending my efforts trying to nail down my repotting timing. Occasionally I get a tree that acts like it was never root pruned, but usually it is a little slow to grow for the first season. I would rather repot every year because the risk of drying out and killing the tree is too high in a colander.
Anthony
Imperial Masterpiece
@0soyoung ,
excellent point, But what a bit of luck. wouldn't you say.
Next step is to take cuttings off the preferred tree and
see if they hold the properties exhibited by the mother.
If it works, it means we have another super cultivar.
Excellent research Scott!
It didn't affect as as we continued on with ground growing
and the secondary branchlet refinement stage.
By the way we have about 10 air-pots at various sizes, though
nothing of the size shown in the Youtube stuff.
We have this Bonsai training at two stages,
1 - ground growing
2 - refinement pot,
The technique of refinement became what sculpture
calls - take away.
We worked on an Oxy last night using overhead lighting
will take a few more years.
Keep up the good work guys.
Anthony
excellent point, But what a bit of luck. wouldn't you say.
Next step is to take cuttings off the preferred tree and
see if they hold the properties exhibited by the mother.
If it works, it means we have another super cultivar.
Excellent research Scott!
It didn't affect as as we continued on with ground growing
and the secondary branchlet refinement stage.
By the way we have about 10 air-pots at various sizes, though
nothing of the size shown in the Youtube stuff.
We have this Bonsai training at two stages,
1 - ground growing
2 - refinement pot,
The technique of refinement became what sculpture
calls - take away.
We worked on an Oxy last night using overhead lighting
will take a few more years.
Keep up the good work guys.
Anthony
Anthony
Imperial Masterpiece
By the way another explanation on why Bonsai development is
so slow.
Air-pots - colander and pond baskets.
Fascinating.
Thanks for the explanation.
Good Day
Anthony
J.B.pines in our climate do well in earthenware pots and our soil mix.
Thus far in the loam in the growing trough, not so hot, even
with additions of 8 mm silica based gravel.
so slow.
Air-pots - colander and pond baskets.
Fascinating.
Thanks for the explanation.
Good Day
Anthony
J.B.pines in our climate do well in earthenware pots and our soil mix.
Thus far in the loam in the growing trough, not so hot, even
with additions of 8 mm silica based gravel.
Lazylightningny
Masterpiece
Yes, excellent thread
Lazylightningny
Masterpiece
There's also another use for pond baskets which has started more than one flame war on this site: using them open to the air for air pruning vs buried in the ground. I have used both methods without a solid conclusion. Buried in the ground, the roots escape into the soil. Then you can come in periodically with a sharp razor blade and shave them off, forcing root ramification in the pot. I doubt if there are any good scientific studies comparing the two methods, though.
Anthony
Imperial Masterpiece
This how we use the colander.
[1] Before placing for ground growing, get a colander that
is about 1/2 to 1 inch larger than the plant's soil mass.
[2] Place no soil under the plant, just place directly into colander.
This encourages the roots at bottom to move into the
soil in the growing trough.
Place bonsai soil mix around the sides.
[3] Give a few weeks to a month and allow the roots to
travel through the fresh mix.
[4] Place into growing trough.
[5] We use a drawn design to the control the growth that follows.
So we get a thicker trunk [ usually 3 inches ] and can add the first
4 / 6 / 8 branches and also get the taper.
The drawing speeds everything up tremendously.
[6] X months later just dig around the colander.
We expect to hit super thick roots.
But the colander protects the core and x weeks later,
we can lift out of the colander and remove large roots, because
there is an abundance of fine roots to handle the surgery.
Just finished doing a Tamarind as stated above.
Next stage branchlet refinement.
Two step Bonsai, say 2 to 5 years and then age.
If we were doing those curves as seen in shimpaku, the seedling would
first be curved by wire or done through clip and grow.
Never have used colanders for air pruning - no need to.
Plus we have 2 colanders set up with Fukien Teas for observation.
Same for double colanders ----- Caribbean pine for observation
Good Day
Anthony
As a reminder - Celtis l.
thick roots safely removed Next branchlet stage.
[1] Before placing for ground growing, get a colander that
is about 1/2 to 1 inch larger than the plant's soil mass.
[2] Place no soil under the plant, just place directly into colander.
This encourages the roots at bottom to move into the
soil in the growing trough.
Place bonsai soil mix around the sides.
[3] Give a few weeks to a month and allow the roots to
travel through the fresh mix.
[4] Place into growing trough.
[5] We use a drawn design to the control the growth that follows.
So we get a thicker trunk [ usually 3 inches ] and can add the first
4 / 6 / 8 branches and also get the taper.
The drawing speeds everything up tremendously.
[6] X months later just dig around the colander.
We expect to hit super thick roots.
But the colander protects the core and x weeks later,
we can lift out of the colander and remove large roots, because
there is an abundance of fine roots to handle the surgery.
Just finished doing a Tamarind as stated above.
Next stage branchlet refinement.
Two step Bonsai, say 2 to 5 years and then age.
If we were doing those curves as seen in shimpaku, the seedling would
first be curved by wire or done through clip and grow.
Never have used colanders for air pruning - no need to.
Plus we have 2 colanders set up with Fukien Teas for observation.
Same for double colanders ----- Caribbean pine for observation
Good Day
Anthony
As a reminder - Celtis l.
thick roots safely removed Next branchlet stage.
Anthony
Imperial Masterpiece
Oh and what really makes the difference is
Practice.
The doing, over and over - becomes like breathing.
Good Day
Anthony
Practice.
The doing, over and over - becomes like breathing.
Good Day
Anthony
Johnathan
Omono
Thank you everyone. Great thread. I just have 1 final question.
For those of us without the ability to plant in the ground, and wanting to thicken trunks... would the best method be as big as possible nursery container? Maybe even a colander/pond basket INSIDE of a nursery container?
My thinking is the pond basket would contain the core of the roots, but you wouldn't want them to be "air pruned" as you'd need more roots for more thickening???
Right? Wrong?
For those of us without the ability to plant in the ground, and wanting to thicken trunks... would the best method be as big as possible nursery container? Maybe even a colander/pond basket INSIDE of a nursery container?
My thinking is the pond basket would contain the core of the roots, but you wouldn't want them to be "air pruned" as you'd need more roots for more thickening???
Right? Wrong?
leatherback
The Treedeemer
I would say.. do as nurseries do. Plant in progressively larger containers through slip potting. In some cases this means having to slip-pot once or twice during the year.
In order to keep the roots more or less decent, I would every 2-3 years do a full repot with root-reduction though.
In order to keep the roots more or less decent, I would every 2-3 years do a full repot with root-reduction though.
As Markyscott noted, there is basically a tradeoff. Air pruning will produce better quality roots (generally finer roots / more feeder roots). Ground or very large container will generally produce faster growth. The faster you grow, the more likely you are to have major root problems requiring big cuts and longer recoveries. Most people ground grow because it is the fastest route to trunk thickness, but then it can take many years to build a good nebari and single layer of feeders from that.
Personally, I think Ebihara proved that if you are an expert, you can container grow a finished tree just as fast as in-ground because the time you lose in thickening you gain in not having to retrain the roots. His technique was basically a grow box and yearly repotting to fix problems quickly.
One important note: colanders only work for air pruning if there is air on the outside. Once you put the colander in a pot or in the ground, you aren't air pruning any more. One cheater technique that does get faster growth is to set the colander ON the ground; some roots will escape, the pot is lifted periodically and the roots are cut back. This will probably produce slightly faster growth and slightly worse roots (tradeoffs!).
Johnathan
Omono
Exactly, my thinking was kinda the best of both worlds. Containing the core roots, yet still allowing some to escape into a larger pot then being able to circle the pot. My logic is every 2 or 3 years you could simply take out the pond basket adjust roots near the trunk accordingly, and then put back into larger container to "grow wild" again.
Ebihara's roots were insane, but would that technique work on all species or just maples? Probably most tropicals, but Does it apply to conifers?
Side note, I can't place on the ground or plant in the ground because I'm worried my dog would urine all over the tree lol
